Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijdrr.2023.103729

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Publishing type：Research paper (scientific journal)  

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

As damage from torrential rains and typhoons increases in various parts of Japan, it is necessary for residents to properly perceive risk of disasters in order to encourage voluntary evacuation actions. In this study, using VR content that allows residents to visually experience flood situation, we examined the transformation of residents' disaster risk perception and disaster prevention awareness through workshops in which residents participated. As a result, residents became aware of storm surge inundation assumptions in a manner consistent with the assumptions in the hazard maps. In addition, it was suggested that the timing of actions such as preparation of items and information related to evacuation and protection of household goods may become earlier and the evacuation routes and locations were changed to avoid flood damage. The results suggest the possibility of improving the awareness of disaster prevention.

DOI： 10.2208/jscejhe.78.2_i_1015

CiNii Research

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

Flooding caused by heavy rains has occurred in many parts of Japan and therefore it is important to encourage voluntary evacuation behavior for damage control. In this study, we examined an evacuation simulation that applies the results of river inundation analysis using iRIC, and examined the effectiveness of vertical evacuation and voluntary shelters. The simulation results show that vertical evacuation is effective, and that evacuation to voluntary shelters increases the evacuation completion rate and reduces the time to complete evacuation. By examining multiple cases of breaches, the possibility of understanding the risk of evacuation in the target river is demonstrated.

DOI： 10.2208/jscejhe.77.2_i_1501

CiNii Research

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Publishing type：Research paper (scientific journal)  

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejhe.77.2_i_1501

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Books

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Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Books

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Books

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2208/jscejhe.73.I_475

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2208/jscejhe.73.I_487

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2208/jscejhe.73.I_481

CiNii Books

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2208/jscejhe.73.I_469

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Though the radar-raingauge analyzed precipitation data is useful to analyze the temporal and spatial<br />
characteristics of precipitation, less attention has been paid on the impact of land-use on precipitation in<br />
study of the urban climate. This study focuses on the availability and the potential of the radar-raingauge<br />
analyzed precipitation data for the evaluation of local and regional rainfall. Thus, for this purpose two<br />
indices, “Rainfall intensity index “and “Rainfall skewed index” has been introduced. We observed that<br />
the 7- year total precipitation shows the urban effect especially in warm season. These indices are<br />
promising for understanding the characteristics of precipitation events, though they hardly detect the<br />
urban effect on precipitation.

DOI： 10.2208/jscejhe.72.I_235

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Language：English   Publishing type：Research paper (scientific journal)  

The classification of clouds and its spatial and temporal variation is important to understand the concept<br />
of local climate. Thus, this study was carried out to explore the potential for using the statistical analysis<br />
(standard deviation) of time series of one hour averaged pyranometer observation to determine the types of<br />
clouds in the Matsuyama plain. Instruments were installed at 6 observation points covering the entire study<br />
area. Clear sky rate was considered as an index to identify the reduction in the solar radiation due to presence<br />
of cloud. The development of high raised cloud such as cirrostratus and cumulus were observed with small<br />
and large time standard deviation respectively and clear sky rate between 0.4 ? 0.6. Also, the formation of<br />
cloud were observed to be high in the urban area and the inland area. This was further verified using the<br />
whole sky images taken by the camera installed at Ehime University. The results would be beneficial for<br />
the study of the rainfall pattern in different part of Matsuyama plain and to understand the effect of<br />
urbanization on the local climate.

DOI： 10.2208/jscejhe.72.I_103

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Language：Japanese   Publisher：水文・水資源学会  

Numerous research projects examining urban surface flux have been conducted during the last two decades.Direct measurements of surface flux using the eddy covariance method facilitated the advancement of quantitative elucidation of the heat balance and CO2 exchange between urban surfaces and the atmosphere. Results show that the heat balance in cities has unique features differing from those of bare ground, vegetation, and forests. This report addresses the following topics: selection of an appropriate observation site for the flux measurement over urban areas, recommendation of instrumentation height in the urban surface layer, and the &quot;surface&quot; concept in cities. Moreover, fundamental examination is made of urban heat balance and CO2 flux in Tokyo, obtained mainly based on the author&#039;s experiments. Some recent research trends of flux measurements over urban areas are described, with introduction of the &quot;Urban Flux Network,&quot; launched as a flux community network.

DOI： 10.3178/jjshwr.29.57

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Japan Society of Civil Engineers  

Spatial and temporal distribution of water vapor is important because local severe rainfall is caused by the convergence of water vapor. On the basis of field measurements in the Matsuyama Plain, we found that urban absolute humidity was lower than rural absolute humidity. Following the manner of urban heat island phenomenon, we call this phenomenon "urban dry island" (UDI). The object of this study was to analyze the features and causes of the UDI. The UDI phenomenon was significantly found at daytime during fine days due to the difference in water vapor fluxes at urban and rural sites. The UDI was most prominent in the morning and in the late afternoon, in time zones where the sea breeze and land breeze altered each other and the wind speed temporally became low. Strong sea breeze transported humid air from the coastal regions to the center of the city and then caused the UDI to diminish. The UDI intensity was large in summer and small in winter. This was attributed to the small latent heat fluxes in winter and strong north-westerly monsoon, which enhanced the mixing of humidity. In addition, we investigated the impact of UDI on the formation of clouds using datasets of cloud base level, which was obtained by a ceilometer in summer. Cloud base level over urban areas tended to be higher than that over rural areas under the condition that the wind blew along the border between urban and rural areas. This was demonstrated by lifted condensation level, which was estimated from surface air temperature and water vapor content.

DOI： 10.2208/journalofjsce.1.1_521

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：公益社団法人 土木学会  

Estimation of global solar radiation from photovoltaic generation was examined using a dataset of pyranometer and solar panel. The solar panel was equipped horizontally and then tilted at an angle of 20o. In the case of horizontally equipped solar panel, the photovoltaic generation was proportional to global solar radiation and once a calibration parameter was attained using one day in one season, solar radiation estimated from photovoltaic generation using the parameter highly agreed with measured data in other days with correlation more than 0.99. The good performance was not only fair weather days but also for other cloudy days. But the calibration parameter was not universal over other seasons. This is probably due to the difference of solar elevation and/or shade effect. In the case of tilted solar panel, the simple conversion resulted in worse and it was demonstrated that the conversion using direct/scatter separation improved the estimation where the correlation is 0.99. The estimation provided in this study is promising for monitoring of spatial and temporal variation of short wave radiation, because solar panel has been already equipped to a lot of houses and commercial, industrial, and public buildings and the generation data can be easily online-based available.

DOI： 10.2208/jscejhe.71.I_421

CiNii Books

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

Spatial and temporal distribution of water vapor is important because local severe rainfall is caused by the convergence of water vapor. On the basis of field measurements in the Matsuyama Plain, we found that urban absolute humidity was lower than rural absolute humidity. Following the manner of urban heat island phenomenon, we call this phenomenon "urban dry island" (UDI). The object of this study was to analyze the features and causes of the UDI. The UDI phenomenon was significantly found at daytime during fine days due to the difference in water vapor fluxes at urban and rural sites. The UDI was most prominent in the morning and in the late afternoon, in time zones where the sea breeze and land breeze altered each other and the wind speed temporally became low. Strong sea breeze transported humid air from the coastal regions to the center of the city and then caused the UDI to diminish. The UDI intensity was large in summer and small in winter. This was attributed to the small latent heat fluxes in winter and strong north-westerly monsoon, which enhanced the mixing of humidity. In addition, we investigated the impact of UDI on the formation of clouds using datasets of cloud base level, which was obtained by a ceilometer in summer. Cloud base level over urban areas tended to be higher than that over rural areas under the condition that the wind blew along the border between urban and rural areas. This was demonstrated by lifted condensation level, which was estimated from surface air temperature and water vapor content.

DOI： 10.2208/journalofjsce.1.1_521

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Matsuyama plain has an obvious contrast of land use in urban and rural area. The purpose of this study is to investigate the effects of differences in land use on the formation of clouds, using the summer time datasets from the observations of cloud base level, solar radiation, surface heat flux, air temperature and humidity. The followings are main outcomes. Cloud base level over urban area was higher than that over rural area when wind blew along the border of the abrupt change of land use. Solar radiation over urban area tended to be smaller than that over rural area in the afternoon of days with a percentage of sunshine ranging from 50% to 80%. This was demonstrated by the development of mixing layer estimated from surface heat flux.

DOI： 10.2208/jscejhe.69.I_1747

J-GLOBAL

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Matsuyama in Ehime Prefecture has often experienced droughts and is one of the water-poorest cities in Japan. The purpose of this study is to analyze the effect of well pumping of groundwater on water resources of the watershed from 1950s to 2010s, using the datasets of groundwater level, river discharge, pumping from wells. The major findings are as follows. The groundwater level and river discharge decreased, while the average precipitation did not change in this term. The volume of water to 9 % of the precipitation in this watershed is pumped up from wells along Shigenobu River. WEP (water and energy transfer process) model, a distributed hydrologic model, shows that the well pumping brings the decrease of the groundwater level in the region from down to middle basin of the river. This agrees well with the fact that the drying up of the river is more extensively observed in recent years compared with that in 1950s.

DOI： 10.2208/jscejhe.69.I_535

J-GLOBAL

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：Japanese   Publisher：日本気象学会  

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In recent years much attention has been paid on urban local climate such as heat island phenomenon and severe rainfall. Urban heat island is known as a phenomenon where urban temperature is higher than rural temperature. Whereas investigation for urban heat island phenomenon has been reported in many cities (e. g., Sakakibara et al., 1996), the investigation of water vapor distribution is still poor. Spatial and temporal distribution of water vapor is as important as air temperature, because local severe rainfall is caused by convergence of water vapor. On the basis of field measurements in Matsuyama plain, we found that urban absolute humidity is lower than rural absolute humidity. Following the manner of urban heat island phenomenon, we call the phenomenon &#039;urban dry island phenomenon&#039;. The object of this study is to analyze the feature and cause of urban dry island phenomenon.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

We examined the cooling effect of rivers under the conditions where surface water existed and where the water disappeared by drought. The followings were main results. There were differences on the surface temperature of the bridge and air temperature within river channel; they were clearly lower than surroundings under the condition of surface water existence, which was not observed in drought condition. However, air temperature above the bridge tends to be always lower than that of surrounding area. This tendency was consistent regardless of the existence of surface water in the river. The reduction of air temperature above the bridge was often observed under the condition where wind direction matched the direction of stream and where the wind speed was high. The influence of low temperature above the rivers reached around the double of river width in the transverse direction.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

We investigate the spatial characteristics of urban-like canopy flow by applying particle image velocimetry (PIV) to atmospheric turbulence. The study site was a Comprehensive Outdoor Scale MOdel (COSMO) experiment for urban climate in Japan. The PIV system captured the two-dimensional flow field within the canopy layer continuously for an hour with a sampling frequency of 30 Hz, thereby providing reliable outdoor turbulence statistics. PIV measurements in a wind-tunnel facility using similar roughness geometry, but with a lower sampling frequency of 4 Hz, were also done for comparison. The turbulent momentum flux from COSMO, and the wind tunnel showed similar values and distributions when scaled using friction velocity. Some different characteristics between outdoor and indoor flow fields were mainly caused by the larger fluctuations in wind direction for the atmospheric turbulence. The focus of the analysis is on a variety of instantaneous turbulent flow structures. One remarkable flow structure is termed &apos;flushing&apos;, that is, a large-scale upward motion prevailing across the whole vertical cross-section of a building gap. This is observed intermittently, whereby tracer particles are flushed vertically out from the canopy layer. Flushing phenomena are also observed in the wind tunnel where there is neither thermal stratification nor outer-layer turbulence. It is suggested that flushing phenomena are correlated with the passing of large-scale low-momentum regions above the canopy.

DOI： 10.1007/s10546-011-9612-6

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

We investigated the diurnal rainfall variation in Matsuyama plain using datasets from AMeDAS, MLIT, and local government. The evening maximum precipitation is especially remarkable in the inland region and along a river. It is known that a river is street of wind for land and sea breezes. Sea breeze would contribute to an increase in the water vapor content over inland regions through the moist air advection from coastal regions. During the period of 1980-2009, the time when the morning maximum precipitation appears shift two hours later every ten years. Similarly, the offshore land breeze is getting more significant at the rate of 200 ms-1h every ten years.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

We investigated turbulent flow around building arrays of four different building aspect ratio (H/W) using large eddy simulation. This simulation was aimed to study the similarity of urban canopy flow and plant canopy flow which was expected with the increase of building aspect ratio. As aspect ratio increased, the streamwise flow speed within the urban canopy decreased. Drag coefficient of urban canopy increased with aspect ratio. This is probably due to the increase of frontal area index and the occurrence of transverse flow along the streets. According to quadrant analyses and turbulence statistics, momentum transfer became more efficient as aspect ratio increased. At a high aspect ratio, momentum was more effectively transferred at cross sections than gaps.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

Rainfall interception ( RI) over an outdoor urban-scale model was investigated from the perspectives of water and energy balance. On average, RI was 6% of the gross rainfall and smaller than typical values in forests. No correlation was found between RI and gross rainfall or rainfall duration unlike the correlations found in forests. Most RI occurred in the first several hours of rainfall, and then RI rapidly decreased with time during a rainfall event. RI was dependent on the saturation deficit at the beginning of the rainfall event. The latent heat for RI was approximately balanced by heat conduction from the concrete surfaces. Differences in the canopy structure are considered as possible reasons for the different behaviors of RI between the present site and forests. Accordingly, three aspects of the canopy structure, i.e., effective wet surface area, efficiency for scalar transfer, and canopy heat capacity, are discussed.

DOI： 10.1029/2008WR007069

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

Temporal and spatial variations in anthropogenic water vapor (AWV) emissions and anthropogenic heat (AH) in Tokyo were estimated using data from a geographic information system (GIS) and an energy-consumption database. The maximum value of AWV exceeded 500 W m(-2) in summer in central Tokyo. Estimations of AWV were validated with field-measured data. The estimated and measured data agreed well, indicating that anthropogenic sources such as district cooling systems release large amounts of water vapor into the atmosphere.

DOI： 10.1029/2007WR006624

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Publisher：Japan Society of Civil Engineers  

Particle image velocimetry (PIV) was applied to the turbulent flow within and above an outdoor urban scale model. The setup of the PIV system and the preliminary results were presented. Two dimensional turbulent flow fields in a vertical cross section of street canyon (3 x 3 m) were measured continuously for 60 min; the spatial and temporal resolutions were 5cm and 1/30 sec, respectively. The mean wind vector and turbulent statistics were successfully obtained. Also the PIV results were validated with measurements of ultrasonic anemometer which is conventional instrument for the investigation of atmospheric turbulence. Most of them showed good agreements within the error of 10% although the data aquisition ratio was still low.

DOI： 10.2208/prohe.52.259

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Publisher：Japan Society of Civil Engineers  

To investigate the impact of the actual sea surface temperature (SST) of Tokyo Bay on urban air temperature, an observation network was constructed. SST had been measured at 14 observation sites, such as the lighted buoy in Tokyo Bay since November 2006 to September 2007, and urban air temperature was simulated using the numerical modeling system, WRF, in which SST obtained from this observation was used. In this study, the following results are obtained.&lt;BR&gt;(1) From observational study, spatial distribution of air temperature is similar to that of SST, and air temperature over Tokyo Bay is considerably affected by air advection from the coastal land area.&lt;BR&gt;(2) Actual SST of Tokyo Bay has significant seasonal and diurnal variation compared with outer SST.&lt;BR&gt;(3) Air temperature at Tokyo increases about 0.1°C in summer if the outer SST is replaced with observed SST in Tokyo Bay in the numerical simulation.

DOI： 10.2208/prohe.52.283

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER METEOROLOGICAL SOC  

Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between kappa B-1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of kappa B-1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that kappa B-1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and kappa B-1, together with a Monin-Obukhov similarity framework.

DOI： 10.1175/JAM2500.1

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Publisher：Japan Society of Civil Engineers  

The interception of rainfall was observed at an outdoor urban scale model site. The model dimensions were 50 x 100 m, with 1.5-m cubic roughness blocks arranged uniformly. The amounts of rainfall and runoff within the area of 6 x 6 m were measured. In this study, we introduced the specification of the facility and preliminary results of rain events which were obtained in September 2006. Mean rainfall intensity of the rainfall events ranged from 0.6 to 1.4 mm hour&lt;SUP&gt;-&lt;/SUP&gt;&lt;SUP&gt;1&lt;/SUP&gt;. Under these rain events, the ratio of runoff to rainfall decreased as the rainfall decreased. This tendency was commonly found in both the total rainfall and the real-time rainfall intensity.

DOI： 10.2208/prohe.51.253

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Publisher：Japan Society of Civil Engineers  

This paper shows the seasonal dependency of vertical profile of air temperature, CO&lt;SUB&gt;2&lt;/SUB&gt;, and H&lt;SUB&gt;2&lt;/SUB&gt;O within and above a suburban canopy and the turbulent diffusivity of the scalars. The results were derived from field measurements of the vertical profiles and fluxes, which were conducted in a residential area (the mean height of canopy is 7.3 m) of Tokyo, Japan. The vertical profile of CO&lt;SUB&gt;2&lt;/SUB&gt; in the daytime drastically varied with the season; the CO&lt;SUB&gt;2&lt;/SUB&gt; concentration within the canopy was lower than that above the canopy in summer but was slightly higher in winter. The seasonal change of the daytime CO&lt;SUB&gt;2&lt;/SUB&gt; profile is likely due to the effect of photosynthesis by vegetation in backyards. The normalized turbulent diffusivity of air temperature and CO&lt;SUB&gt;2&lt;/SUB&gt; depended on height and atmospheric stability, which is similar to that for vegetated canopies. In contrast, the normalized turbulent diffusivity of H&lt;SUB&gt;2&lt;/SUB&gt;O was relatively smaller than that of heat and CO&lt;SUB&gt;2&lt;/SUB&gt;. Although the correlation coefficients indicated that the transfer efficiencies of CO&lt;SUB&gt;2&lt;/SUB&gt; were generally smaller than that of heat, the magnitude of normalized turbulent diffusivity of air temperature and CO&lt;SUB&gt;2&lt;/SUB&gt; was almost same.

DOI： 10.2208/prohe.51.271

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：METEOROLOGICAL SOC JAPAN  

This paper describes land-surface parameters, including the roughness lengths of momentum, heat, and water vapor, and the surface moisture availability derived from 1 year of field measurements at a suburban site in Tokyo, Japan. The main results are as follows. The estimated ratio of roughness length of momentum to heat, kB(T)(-1), had an average value of 7. This value of kB(T)(-1) was larger than those documented for vegetated and agricultural surfaces, but less than that reported for a light industrial area. In winter, kB(T)(-1) tended to be smaller, suggesting dependence on the vertical position of the heat source within the canopy. The kB(T)(-1) results also showed a diurnal change, in which higher values occurred in the afternoon. The parameter kB(q)(-1), the ratio of the roughness length of momentum to water vapor, ranged from 40 to 600. The parameter kB(q)(-1) depended on the water vapor deficit, the friction velocity, and the number of elapsed days after precipitation, all of which can change surface water availability. The value of surface moisture availability, beta, ranged from 0.02 to 0.3. beta gradually decreased with the number of elapsed days after precipitation.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The spatial variability of both turbulent flow statistics in the roughness sublayer (RSL) and temperature profiles within and above the canopy layer (CL) were investigated experimentally in a densely built-up residential area in Tokyo, Japan. Using five towers with measuring devices, each tower isolated from the others by at least 200 m, we collected high-frequency measurements of velocity and temperature at a height z =1.8 z(H), where z(H), the mean building height in the area, is 7.3 m. Also, temperature profiles were measured from z = 0.4 to 1.8 z(H). The 'real mean' geometric parameters that were obtained for the areas within 200 m of each tower were fairly homogeneous among the tower sites. The main results are as follows: (1) The spatial variability of all RSL turbulent statistics, except the sensible heat flux, was comparable to that reported in a pine forest. Also, the variability decreased with increasing friction velocity. (2) The spatial variability of the RSL sensible heat flux was larger than that reported in a pine forest. Also, the variability depended on the time of the day and became larger in the morning. The difference among the sites was well related to the areal fraction of vegetation. (3) The spatial variability of the CL temperature profile depended on the time of the day and became larger in the morning. Nevertheless, the spatial standard deviation of CL temperature was always below 0.7 K. (4) It is suggested that the "warming-up" process in the morning when heat storage is dominant increases the spatial variation of RSL sensible heat flux and CL temperature according to the local properties around each tower and the variation decreases once there is further convective mixing in the midday.

DOI： 10.1007/s10546-006-9063-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

We investigated the 'local' and 'global' similarity of vertical turbulent transfer of heat, water vapour, and CO2 within an urban surface layer. The results were derived from field measurements in a residential area of Tokyo, Japan during midday on fair-weather days in July 2001. In this study, correlation coefficients and quadrant analysis were used for the evaluation of 'global' similarity and wavelet analysis was employed for investigating 'local' similarity. The correlation coefficients indicated that the transfer efficiencies of water vapour and CO2 were generally smaller than that of heat. Using wavelet analysis, we found that heat is always efficiently transferred by thermal and organized motions. In contrast, water vapour and CO2, which are passive quantities, were not transferred as efficiently as heat. The quadrant analyses showed that the heat transfer by ejection exceeded that by sweep, and the ratios of ejection to sweep for water vapour and CO2 transfer were less than that for heat. This indicated that heat is more efficiently transferred by upward motions and supported the findings from wavelet analysis. The differences of turbulent transfer between heat and both CO2 and water vapour were probably caused both by the active role of temperature and the heterogeneity in the source distribution of scalars.

DOI： 10.1007/s10546-005-9034-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

This study concerns the build-up of carbon dioxide, hereafter CO2, within a suburban canopy under nocturnal stably stratified conditions. The results were derived from wintertime field measurements of the vertical profiles of CO2, air temperature and turbulent exchange processes, in a residential area with a mean canopy height of 7.3 m in Tokyo, Japan. In the daytime, especially under very windy conditions, the CO2 concentration measured at a reference height of 29 in a.g.l. was almost the same as the background CO2 concentration (380ppmv). In contrast, during night-time the CO2 concentration significantly increased under stably stratified conditions. We therefore examined the ensemble mean vertical profile of CO2 concentration using the bulk Richardson number (Rb) as a stability index. Under stably stratified conditions (Rb &gt; 5), the CO2 concentration above the canopy decreased with height such that the difference between within and above the canopy was as high as 40 ppmv. In contrast, the CO2 concentration within the canopy stayed at almost the same level, which indicates that the CO2 emitted from the houses accumulated within the canopy. Such behavior was not found in the H2O profile. We argue that these concentration profiles of CO2 and H2O are influenced by subsiding cold air from the rooftop, thus drawing the high CO, levels from ventilation fans down towards the ground. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.atmosenv.2005.10.059

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Language：English   Publishing type：Research paper (international conference proceedings)  

Scopus

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Publisher：Japan Society of Civil Engineers  

In urban area, water and heat transfer is not decided only by surface energy balance, but also by artificial effects including waterworks and sewage system. To investigate how water and heat are transferred in urban catchment, meteorological and hydrological values are observed over one year. The catchment is a residential area located in Tokyo metropolitan and the area is 12.2ha. The following results are obtained.&lt;BR&gt;Groundwater from soil into sewer occupies 29% of whole wastewater by evaluating water balance of the catchment. The heat added by water use is up to 3.4 W m&lt;SUP&gt;-2&lt;/SUP&gt; in winter and the value is 10% of whole anthropogenic heat. In winter, the heat that the wastewater gains through flowing the catchment is 28% of ground heat flux as a residual heat of surface heat balance.

DOI： 10.2208/prohe.50.511

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DOI： 10.1007/s00704-005-0150-3

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Publisher：Japan Society of Civil Engineers  

The vertical profiles and horizontal distribution of atmospheric turbulence were observed at an outdoor urban scale model site. The model dimensions were 50 x 100m, with 1.5-meter cubic roughness blocks arranged uniformly. Eight sonic anemometers were arranged vertically or horizontally in the site to obtain the vertical profiles or horizontal distribution. In this study, we focused on the atmospheric stability effect on the vertical profiles and the horizontal distribution of the turbulent structure over the model site.&lt;BR&gt;The quadrant analysis was conducted using the data set of the vertical distribution. The analysis showed the dependence of the turbulent motion on the atmospheric stability (z&#039;/L). The sweep mode is mostly dominant at all height in the surface layer when the stability is stable. In case of the unstable atmospheric condition, the ejection mode can crossover the sweep mode at the higher portion in the surface layer.&lt;BR&gt;The streak pattern was observed in a turbulent flow over the building like roughness from the measurement of the horizontal distribution. The width was about 3 or 6 times larger than that of the blocks. This result strongly implies the importance of the horizontal distribution the turbulent structure over urban area.

DOI： 10.2208/prohe.50.445

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Publisher：Japan Society of Civil Engineers  

In this study, we have investigated the fluxes of energy, H&lt;SUB&gt;2&lt;/SUB&gt;O and CO&lt;SUB&gt;2&lt;/SUB&gt; between the water surface and the atmosphere over Tokyo Bay. And we compared these fluxes with those at a suburban area (Kugahara) in Tokyo, Japan. From recent observations (2004/12-2005/8), the interesting features of energy and scalar fluxes in Tokyo Bay were verified: 1) Sensible heat flux was positive in winter whereas it was negative in summer. 2) Positive latent heat flux was large in winter and it was dependent on wind speed. 3) The CO&lt;SUB&gt;2&lt;/SUB&gt; flux in the suburban area was positive (CO&lt;SUB&gt;2&lt;/SUB&gt; source), whereas that in Tokyo Bay was negative (CO&lt;SUB&gt;2&lt;/SUB&gt; sink). These results were probably due to the advection of air from the urban area.

DOI： 10.2208/prohe.50.463

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Publisher：Japan Society of Civil Engineers  

In this study we focused on the relationships between the vertical profiles of scalar within and above a suburban canopy and the cold-air subsidence locally generated within the canopy. The results were derived from the wintertime field measurements of the vertical profiles of CO&lt;SUB&gt;2&lt;/SUB&gt;, air temperature, water vapor, and turbulent flows, which were conducted in a residential area (the mean height of canopy is 7.3 m) of Tokyo, Japan. Under stably stratified conditions, the CO&lt;SUB&gt;2&lt;/SUB&gt; concentration above the canopy decreased with height, while that within the canopy kept almost same level. This indicates that the CO&lt;SUB&gt;2&lt;/SUB&gt; emitted from the houses accumulated within the canopy. Such behavior was not found in H&lt;SUB&gt;2&lt;/SUB&gt;O profile. The vertical profile of air temperature and observations on the surface temperature using a thermal infrared camera suggested that the cold air generated at roof level moved down to the ground level. The effect of &#039;cold air subsidence&#039; within the canopy is the most plausible reason for the nighttime vertical profiles of CO&lt;SUB&gt;2&lt;/SUB&gt; and H&lt;SUB&gt;2&lt;/SUB&gt;O.

DOI： 10.2208/prohe.50.493

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

A simple urban energy balance model for mesoscale simulations (SUMM) was tested using results from an outdoor scale-model experiment. The model geometry is assumed to be an infinitely extended regular array of uniform buildings, each of which is composed of six faces (roof, floor, and four vertical walls). The SUMM explicitly considers the three dimensionality of surface geometry and theoretically predicts the energy balance at each face without time-consuming iterations. The SUMM was compared with outdoor scale-model experiments. The simulated energy balance and surface temperatures agree well with the values measured on a reduced-scale hardware model corresponding to the numerical model geometry.

DOI： 10.1007/s10546-004-7956-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The seasonal trend of vertical temperature profiles within and above an urban canopy has been investigated. We measured air temperatures and wind velocities along a 29-m tower in a residential area of Tokyo, Japan continually for 14 months. The height of the daily maximum temperature Z(Tmax) varied with the season; Z(Tmax) was at the roof level in winter but near the ground in summer. The seasonal change of Z(Tmax) is likely due to the change of height at which solar energy is absorbed. At the time of the maximum temperature, the atmosphere above the canopy is always unstable whereas the air within the canopy is unstable in summer but stable in winter.

DOI： 10.1007/s10546-004-5644-5

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Publisher：Japan Society of Civil Engineers  

Based on one year of field measurements, we described the annual fluxes of energy and CO&lt;SUB&gt;2&lt;/SUB&gt; at a residential area of Tokyo. The major findings are as follows. 1) The total of &lt;I&gt;Rn&lt;/I&gt;, &lt;I&gt;H&lt;/I&gt;, and &lt;I&gt;LE&lt;/I&gt; was 2.36, 1.35, and 0.90 GJ m&lt;SUP&gt;-2&lt;/SUP&gt;, respectively. The latent heat flux &lt;I&gt;LE&lt;/I&gt; was large despite the small areal fraction of natural coverage (trees and bare soil). The estimated local latent heat flux per unit natural coverage was two times larger than the available energy (&lt;I&gt;Rn&lt;/I&gt;+&lt;I&gt;A&lt;/I&gt;), which indicates that the &#039;&#039;oasis effect&#039; was significant. 2) The annual CO&lt;SUB&gt;2&lt;/SUB&gt; flux was upward due to fossil fuel consumption in houses and traffic and human bodily exhalations. The total CO&lt;SUB&gt;2&lt;/SUB&gt; flux was 3352 gC m&lt;SUP&gt;-2&lt;/SUP&gt; and was six times larger than the downward CO&lt;SUB&gt;2&lt;/SUB&gt; flux at a typical temperate deciduous forest.

DOI： 10.2208/prohe.49.361

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Publisher：Japan Society of Civil Engineers  

Based on one year of field measurements, we described the annual fluxes of energy and CO<SUB>2</SUB> at a residential area of Tokyo. The major findings are as follows. 1) The total of <I>Rn</I>, <I>H</I>, and <I>LE</I> was 2.36, 1.35, and 0.90 GJ m<SUP>-2</SUP>, respectively. The latent heat flux <I>LE</I> was large despite the small areal fraction of natural coverage (trees and bare soil). The estimated local latent heat flux per unit natural coverage was two times larger than the available energy (<I>Rn</I>+<I>A</I>), which indicates that the ''oasis effect' was significant. 2) The annual CO<SUB>2</SUB> flux was upward due to fossil fuel consumption in houses and traffic and human bodily exhalations. The total CO<SUB>2</SUB> flux was 3352 gC m<SUP>-2</SUP> and was six times larger than the downward CO<SUB>2</SUB> flux at a typical temperate deciduous forest.

DOI： 10.2208/prohe.49.361

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER METEOROLOGICAL SOC  

Based on 1 yr of field measurements, the diurnal, seasonal, and annual fluxes of energy and carbon dioxide (CO2) at a residential area of Tokyo, Japan, are described. The major findings are as follows. 1) The storage heat flux G in the daytime had little seasonal variation, irrespective of significant seasonal change of net all-wave radiation Rn. 2) The latent heat flux in the summer daytime was large despite the small areal fraction of natural coverage ( trees and bare soil). The estimated local latent heat flux per unit natural coverage was 2 times the available energy (Rn - G), which indicates that the "oasis effect'' was significant. 3) The CO2 flux was always upward throughout the year and the magnitude was larger in winter, mainly because of an increase of fossil fuel consumption. The annual total CO2 flux was 6 times the downward CO2 flux at a typical temperate deciduous forest.

DOI： 10.1175/JAM2153.1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Large-eddy simulations have been performed for fully developed turbulent flow within and above explicitly resolved simple cube arrays. The results from our model, hereafter LES-CITY, are shown to agree with laboratory experiments. We investigated the systematic influence of cube density on turbulent flow characteristics by performing numerical experiments for cube areal densities from 0 to 44%. The following results were obtained: (1) The dispersive momentum flux was quite large within the canopy layer due to a mean stream re-circulation, whereas it was smaller above the canopy. The spatial variation of temporally averaged momentum in the roughness sub-layer was 20% or less of the total kinematic surface drag. (2) The temporally and spatially-averaged flow structure confirmed the existence of conventionally described canyon flow regimes; isolated, interfacial, and wake. However, the intermittency of the canyon flow for all cube densities was quite large and the stream patterns were never persistent. (3) Turbulent organized structures (TOS) similar to those observed in turbulent surface-layer flows were simulated, which are characterized by longitudinally-elongated low speed streaks and the corresponding shorter streamwise vortices. The streaks in sparse and dense canopy flows were likely to be aligned to the street line and to the roof lines, respectively. Such heterogeneity of TOS partially accounts for the large spatial variation of momentum flux. (4) In contrast to the mixing layer analogy of vegetation flows, the TOS and the resulting turbulent statistics of urban flow above the canopy resembled those in surface layers. The recirculation within the canopy significantly influenced the turbulent statistical properties.

DOI： 10.1023/B:BOUN.0000027909.40439.7c

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Publisher：Japan Society of Civil Engineers  

We investigate shear functions for momentum (&lt;I&gt;φ&lt;SUB&gt;M&lt;/SUB&gt;&lt;SUP&gt;-1&lt;/SUP&gt;&lt;/I&gt;) and heat (&lt;I&gt;φ&lt;SUB&gt;H&lt;/SUB&gt;&lt;SUP&gt;-1&lt;/SUP&gt;&lt;/I&gt;) and linear correlation coefficients of them (-&lt;I&gt;r&lt;SUB&gt;uw&lt;/SUB&gt;&lt;/I&gt; |&lt;I&gt;r&lt;SUB&gt;wT&lt;/SUB&gt;&lt;/I&gt;|) using data acquired over an urban surface layer in Tokyo Japan. Field measurement was conducted on a 29m height tower, 4 times the canopy height of 7.3m. 3D sonic anemometers were installed at 4 heights in the region 1.5&lt;I&gt;z&lt;SUB&gt;h&lt;/SUB&gt;&lt;/I&gt;&lt;&lt;I&gt;z&lt;/I&gt;&lt;4&lt;I&gt;z&lt;SUB&gt;h&lt;/SUB&gt;&lt;/I&gt; and fine wire thermocouples were mounted at 10 heights from the ground to the top. Main conclusions were obtained as follows.(1) Momentum flux decreases with height. Non-dimensional horizontal wind velocity follows a conventional stratified logarithmic profile when it is scaled by the shear stress extrapolated to the roof top level. However, the locally scaled wind profile fails the agreement.(2) Both of &lt;I&gt;φ&lt;SUB&gt;M&lt;/SUB&gt;&lt;SUP&gt;-1&lt;/SUP&gt;&lt;/I&gt; and -&lt;I&gt;r&lt;SUB&gt;uw&lt;/SUB&gt;&lt;/I&gt; have the dependency on height and they are enhanced near the canopy due to the &#039;bluff body&#039; effect.(3) At a height of &lt;I&gt;z&lt;/I&gt;/&lt;I&gt;z&lt;SUB&gt;h&lt;/SUB&gt;&lt;/I&gt; =2.7, &lt;I&gt;φ&lt;SUB&gt;M&lt;/SUB&gt;&lt;SUP&gt;-1&lt;/SUP&gt;&lt;/I&gt; follows the conventional similarity function while -&lt;I&gt;r&lt;SUB&gt;uw&lt;/SUB&gt;&lt;/I&gt; is still larger than a conventional one. The &#039;bluff body&#039; effect appears more significantly in -&lt;I&gt;r&lt;SUB&gt;uw&lt;/SUB&gt;&lt;/I&gt;.(4) Both of &lt;I&gt;Φ&lt;SUB&gt;H&lt;/SUB&gt;&lt;SUP&gt;-1&lt;/SUP&gt;&lt;/I&gt; and |&lt;I&gt;r&lt;SUB&gt;wT&lt;/SUB&gt;&lt;/I&gt;| have a good agreement with the conventional function and the dependencies on height are not found. In the case of heat, the conventional similarity theory can be applied to the urban surface layer.

DOI： 10.2208/prohe.48.139

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Publisher：Japan Society of Civil Engineers  

The water and energy transport dynamics in urban catchments are investigated to facilitate better understanding of thermo-hydrological impact of urbanization on the receiving water. For this purpose, meteorological and hydrological variables have been monitored in a catchment with an area of 12.2ha located in the central Tokyo District. The amounts and dynamic patterns of urban wastewater showed quite reasonable results compared with existing survey reports. The time variation of sewage temperature showed a distinct diurnal pattern, which reflects water and energy consumption characteristicsin residential houses and is insensitive to a day of the week and season. In a thunderstorm event, the impact of summertime urban heating on the runoff was revealed by an abrupt increase of storm temperature. Finally, a dynamical model was proposed to estimate sewage temperature in response to hydrological and meteorological conditions as well as human behavior of water and energy consumption.

DOI： 10.2208/prohe.48.175

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Publisher：Japan Society of Civil Engineers  

Large Eddy Simulations have been performed for fully developed turbulent flow within and above explicitly resolved simple cube arrays. The model (LES-CITY) was validated in comparison with laboratory experiments. The systematic influence of cubic density on turbulent flow characteristics was investigated through numerical experiments in a wide range of cubic area density (0 to 0.44).&lt;BR&gt;The following results were obtained. 1) The intermittency of flow: the temporally and spatially averaged flow structure confirms the existence of conventionally described canyon flow regime. However, the intermittency of the canyon flow for any cubic densities is large and the stream patterns are never persistent. 2) Turbulent Organized Structures (TOS): TOS are characterized by longitudinally elongated low speed streaks and corresponding streamwise vortices. The streaks in sparse and dense canopy flows are likely to be aligned to the street-line and to the roof-line, respectively.

DOI： 10.2208/prohe.48.607

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Publisher：Japan Society of Civil Engineers  

To investigate the characteristics of potential temperature profiles, a field observation was continuously carried out at a residential site in Tokyo. Following results were obtained; 1) In winter the potential temperature has a maximum value around the roof top level, whereas in summer near the ground surface. The heat source moves up and down due to the seasonal and daily change of solar angle. This isa distinctive characteristic of the micrometeorology of the urban canopy contrast to vegetation canopy. 2) The maximum temperature at the roof top level implies that inversion layer is formed within the canopy. This is directly confirmed by the turbulent flux measurement.

DOI： 10.2208/prohe.48.163

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Language：Japanese   Publisher：水文・水資源学会  

DOI： 10.3178/jjshwr.16.477

CiNii Books

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Language：Japanese   Publisher：水文・水資源学会  

DOI： 10.3178/jjshwr.16.491

CiNii Books

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Publisher：Japan Society of Civil Engineers  

To investigate the dependencies of the profiles on the atmospheric stability (z&#039;/L), field measurementsw ere carried out for wind velocity, temperature and turbulent fluxes in and above a dense residential canopy. 1) The vertical profile of wind velocity varies with (z&#039;/L). It deviates from the conventional similarity function in the unstable condition. 2) Momentum flux slowly decrease with height. This tendency is more significant in the unstable condition. 3) Skewness of u above the canopy is larger than the value reported in the vegetation studies. 4) Inversion layer is formed within the canopy around the sunrise due to the local heating of air near the roof top. 5) The gradient of potential temperature under unstable condition is dependent on the atmospheric stability but is relatively larger than the one of the conventional similarity function. 6) The range of roughness sub-layer for heat is smaller than the one for momentum.

DOI： 10.2208/prohe.47.1

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Language：Japanese   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

A long-term field measurement was performed to investigate turbulent transfer in a densely built-up urban surface layer. The turbulent transfer efficiencies of heat, vapor, and CO&lt;SUB&gt;2&lt;/SUB&gt; were examined. In the morning the low-frequency eddies penetrating the entire atmospheric boundary layer transfer water vapor efficiently due to the entrainment of dry air from upper to the surface. M.O.S. theory predicts that relative transfer efficiencies are unity and have no dependency on stability. But ratios for vapor/heat and CO&lt;SUB&gt;2&lt;/SUB&gt;/heat observed show that the transfer efficiencies of vapor and CO&lt;SUB&gt;2&lt;/SUB&gt; are smaller than heat. This tendency is more significant in unstable condition. In order to discuss this result, wavelet analysis for transfer efficiency of scalars was conducted. The thermal structure and organized structure transfer heat efficiently. Vapor and CO&lt;SUB&gt;2&lt;/SUB&gt; are also transferred as well as heat by some structures. But they are not or adversely transferred by other structures. Followings are considered as this reason. (1) Heat is an active scalar and produces the thermal structures by itself. Hence, the heat is transferred most efficiently. Vapor and CO&lt;SUB&gt;2&lt;/SUB&gt; are transferred passively and the efficiency is less than heat. (2) The absorption/source of vapor and CO&lt;SUB&gt;2&lt;/SUB&gt; is inhomogeneous. As a result, the heterogeneity of vapor and CO&lt;SUB&gt;2&lt;/SUB&gt; concentration distribution causes their transfer efficiency lower.

DOI： 10.3178/jjshwr.16.491

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Language：Japanese   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

A 30m-height tower has been installed in a uniform low-storied residential area in Tokyo, Japan. Radiation, heat, water vapor and CO&lt;SUB&gt;2&lt;/SUB&gt; fluxes were measured continuously for one year. In this study, the seasonal and diurnal variations of fluxes were discussed using the data which were ensemble-averaged over all clear days of one month. The contributions of garden trees, concrete materials, transportation, human lives, and human body to latent heat and CO&lt;SUB&gt;2&lt;/SUB&gt; fluxes were also investigated. The main conclusions are as follows. (1) Latent heat flux observed in the daytime during summer was larger than the conventional value. Assuming that this is only due to evaporation from garden trees-their area portion is less than 30%, the latent heat flux per unit vegetation area should be twice as much as the value reported for the forest near the urban. Garden trees might have a high potential to evaporate vapor due to the oasis effect. Concrete materials are found to be one of the evaporation sources and the contribution is not negligible in winter. (2) CO&lt;SUB&gt;2&lt;/SUB&gt; flux was positive throughout the year. The most dominant emissions of CO&lt;SUB&gt;2&lt;/SUB&gt; are attributed to human lives and vehicles due to the consumption of fossil fuels. The magnitude of CO&lt;SUB&gt;2&lt;/SUB&gt; flux in winter was larger than that during summer. This seasonal change is mainly due to the increase of fuel consumption in human lives during winter and the absorption of CO&lt;SUB&gt;2&lt;/SUB&gt; by plant photosynthesis in summer.

DOI： 10.3178/jjshwr.16.477

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DOI： 10.3178/jjshwr.16.477

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Field observations of area-averaged turbulence characteristics were conducted in a densely built-up residential neighbourhood in Tokyo, Japan. In addition to eddy-correlation (EC) sensors a scintillometer was used for the first time in a city. Significant results include: (1) Scintillometer-derived sensible heat fluxes, Q(H), obtained at a height 3.5 times the building height agree well with those using the EC technique; (2) source areas for the scintillometer fluxes are larger than for the EC sensors, so that at low heights over inhomogeneous terrain scintillometry offers advantages; (3) new similarity relationships for dissipation rates are proposed for urban areas; (4) a new technique that uses simultaneous scintillation measurements at two heights to directly estimate area-averaged zero-plane displacement height, z(d), is proposed. z(d) estimated in this way depends slightly on atmospheric stability (lower z(d) under more unstable conditions).

DOI： 10.1023/A:1019668424982

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Publisher：Japan Society of Civil Engineers  

Using the data of the continuous field observation at residential site in Tokyo from March 2001, following results are obtained; 1) The existence of constant-flux layers for momentum, sensible-heat and latent-heat flux above the urban area are confirmed. 2) The probabilities of constant-flux layer achievement (C. F.-rate) are 32.5%, 51.1%, 43.9% and 17.0%, for momentum, sensible-heat, latentheat and carbon dioxide flux, respectively. The C. F.-rate for all fluxes simultaneously is only 0.9%. 3) In this observation site, the C. F.-rate is less affected by the wind direction but slightly related to the atmospheric stability. 4) When a large-scale turbulence or front passes through a sensor, the sensible-heat flux ratio of 29m to 21m is diverted from 1.

DOI： 10.2208/prohe.46.79

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Publisher：Japan Society of Civil Engineers  

Land-surface parameters of urbanized terrain are evaluated based on the field measurement data. Following results are obtained;(1) The value of momentum roughness length (Z&lt;SUB&gt;0&lt;/SUB&gt;) is 1.56m and it is greater than the heat roughness length (z&lt;SUB&gt;T&lt;/SUB&gt;) and water vapor roughness length (Z&lt;SUB&gt;q&lt;/SUB&gt;). The ratios kB&lt;SUB&gt;T&lt;/SUB&gt;&lt;SUP&gt;-1&lt;/SUP&gt;=ln (Z&lt;SUB&gt;0&lt;/SUB&gt;/Z&lt;SUB&gt;T&lt;/SUB&gt;) and kB&lt;SUB&gt;q&lt;/SUB&gt;&lt;SUP&gt;-1&lt;/SUP&gt;=ln (Z&lt;SUB&gt;0&lt;/SUB&gt;/Z&lt;SUB&gt;q&lt;/SUB&gt;) are 8.0 and 20.5 respectively.(2) The value of evaporation efficiency (β) is 0.05-0.2. After precipitation β is significantly decreasing with time for a few weeks. Evaporations from vegetation and concrete material are estimated respectively. Vegetation has a potential to emit latent heat as much as net radiation due to the oasis effect. Concrete material has a potential to cover the β variation range over residential area. When horizontal wind velocity is large, β is decreased.(3) The averaged value of albedo is about 0.13. When there is rainfall, albedo is decreased. But the value is back to about 0.13 within 2-3 days.

DOI： 10.2208/prohe.46.91

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Publisher：Japan Society of Civil Engineers  

This study demonstrates the numerical prediction of thermal sensation index for outdoor environment (SET*OUT) using Regional Atmospheric Modeling System (RAMS). SET*OUT, one of the major thermal sensation index, requires data sets of wind velocity, absolute humidity, air temperature and each component of short wave and long wave radiation in both upward and downward directions. Temporal and spatial variation of SET*OUT over the Kanto Region on August 10 1998 has been presented and discussed. The thermal sensation index for indoor environment (SET*IN) is referred to as a comparison. It is found that the variation of SET*OUT is strongly influenced by mean radiation temperature and sea breeze penetration. The mean radiation temperature, and consequently SET*OUT, have distinctive double peaks in the morning and the afternoon due to the shape factor of cylindrical human body for direct solar radiation. The first peak of SET*OUT in the morning roughly corresponds to the arrival of sea breeze front, and the value is generally larger than that of the second peak in the afternoon. Such a behavior of SET*OUT can be accounted for by the fact that the sea breeze increases wind velocity and activate the heat transfer from human body. SET*IN is similar to but slightly (0.5-1°C) larger than air temperature, which is due to the high humidity condition in Tokyo area.

DOI： 10.2208/prohe.45.259

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Publisher：Japan Society of Civil Engineers  

The present study uses observational data from a residential site in Tokyo, Japan and a rice paddy in Chiba Pref., Japan, to investigate the relative facility with heat, water vapor, and carbon dioxide are transported by turbulence in the surface layer. The ratios of linear correlation coefficients |rwT/ruw| and |rwq/ruw| increase with stability and the ratios at residential area are generally smaller than at rice paddy due to bluff-body effects. At rice paddy, the ratios of linear correlation coefficient |rwc/rwq| is generally smaller than unity. Meanwhile at the residential area, the distribution of the ratio |rwc/rwq| scatters to |z&#039;/L|. This inequality may be caused by the complex source patterns of the urban surface and the vertical profile within the canopy. Inequalities of transfer between T, c, and q will imply that the diffusion coefficient between them have different value respectively.

DOI： 10.2208/prohe.45.253

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Language：Japanese   Publisher：社団法人日本気象学会  

This study uses observational data from urban sites in Setagaya, Vancouver and Ginza, to investigate the applicability of conventional Monin-Obukhov similarity functions.The following results are obtained;(1)The ration of linear correlation coefficients of heat and momentum transfer are generally smaller than conventional values in rural sites due to bluff body effect.(2)Non-dimensional form of (a) standard deviations of velocity, (b)standard deviation of temperature, (c) dissipation ration of temperature variances, and (d) dissipation ration of kinetic energy, as a function of stability paramenter, are proposed.All of these also show more or less different curves from conventional relationships in rural sites.

CiNii Books

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Language：Japanese   Publisher：社団法人日本気象学会  

Field observations to investigate area-averaged turbulence characteristics were performed in a densely built-up residential neighborhood in Tokyo, Japan.Besides eddy-correlation sensors, a scintillometer was used in an urban environment.Several important results are summarized as follows : (1) Radiation balance and energy balance of observation area are obtained.(2) A new technique which uses simultaneous scintillation measurements at two heights is developed to estimate directly both area-averaged zero-plain displacement height Z_d and heat flux Q_H.The estimated Z_d is found to be slightly dependent on the atmospheric stability parameter (lower Z_d under more unstable conditions).(3) Source areas for the scintillometer are 2-3 times larger than those for the eddy correlation sensors under unstable conditions.30-min averaged, normalized standard deviations of Q_H measured by the two methods are compared. Whilst Q_H estimates agree well, their short time variability was generally larger for the eddy-correlation as compared with the scintillometer data under wide range of stability conditions.This result can be attributed to the superior spatial integration due to the longer averaging path (250 m) of the scintillometer.It is concluded that time-averaging requirements to obtain representative flux measurement for scintil-lometer applications can be relaxed.

CiNii Books

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Publisher：Japan Society of Civil Engineers  

Field observation was performed to investigate the atmospheric structure and concentration of CO&lt;SUB&gt;2&lt;/SUB&gt;, SPM (Suspended Particle Matter) over Tokyo Bay by using Radio Sonde, Doppler Sodar and airplane in summer 1999.&lt;BR&gt;The following results were obtained; 1) There is a descent-flow over Tokyo Bay. The peak value exits at the height of 300m. This expects the existence of circulation flow between Tokyo Bay and surrounding area. 2) The rise in potential temperature in the daytime is caused by the local descent-flow. 3) The vertical and horizontal distribution of SPM and CO&lt;SUB&gt;2&lt;/SUB&gt; is different each other. Vertical gradient of CO&lt;SUB&gt;2&lt;/SUB&gt; is positive over the bay. CO&lt;SUB&gt;2&lt;/SUB&gt; is transported over Tokyo Bay from surrounding high emission area. Vertical gradient of SPM is negative.The profile is affected by the emission of sea-salt at the surface of the bay and Pacific ocean.

DOI： 10.2208/prohe.44.79

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Language：Japanese  

DOI： 10.2208/prohe.43.233

CiNii Books

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DOI： 10.2208/prohe.43.91

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Publisher：Japan Society of Civil Engineers  

Field observation was performed on two islands located in Tokyo Bay to investigate the atmospheric environment over Tokyo Bay by using Radio Sonde, Dopper Sodar and airplane in summer 1998.&lt;BR&gt;The following results were obtained; 1) The atmospheric boundary layer (ABL) over Tokyo Bay was composed of multiple layers.Especially, it was composed of three layers on August 10. 2) These multiple layers were formed by the effect of various kinds of return flows from the land. The upper boundary layer about 1250-2000m over Tokyo Bay was hotter and drier than the one over the land. 3) The airplane observation suggests that the air pollutant might be more concentrated over Tokyo Bay rather than over the land due to the difference of the boundary layer structure.

DOI： 10.2208/prohe.43.233

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Publisher：Japan Society of Civil Engineers  

Three types of experiments on the measurements of spatially mean heat flux were performed by using two sets of scintillometer. In the Case-1, two sets of scintillometer are located adjacently and parallel, in the Case-2, their propagation paths are crossed, and in the Case-3 they are located parallel at the different height. The following results are obtained; 1) the fluctuations of the sensible heat fluxes measured by closely located scintillometer agree with each other, 2) the crossed scintillometer agree well when they are averaged every 30min, but their 1 min-averaged data don&#039;t agree, 3) the method to estimate the regional zero-displacement height &quot;&lt;I&gt;d&lt;/I&gt;&quot; by using two sets of scintillometer is checked and the proper height of &lt;I&gt;d&lt;/I&gt; is derived.

DOI： 10.2208/prohe.43.91

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Language：Japanese   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

Potential effects of urban vegetation on the atmospheric environment in the Kanto area were estimated by coupling the plant-physiological characteristics of Meiji-shrine forest (Kanda et al., 1997a, b) and the output of meso scale meteorological simulation (Fukuda et al, 1997). A total of four functions of vegetation were discussed, which were (1) transpiration (mitigation of urban heat island), (2) photosynthesis (CO2 assimilation) (3) O3 absorption (purification of the atmosphere) and (4) emission of terpene (relaxation effect). The numerical calculation was performed for 27 July in 1995, the calm and clear day in summer. The following results were obtained; 1) The stomatal opening in urban areas was restrained mainly by the larger water vapor deficit of the urban atmos-phere, 2) this lead to the lower level of CO2 assimilation and O3 absorption in urban areas than in rural areas, 3) the emission of terpenes, which were controlled dominantly by leaf temperature, were larger in the urban areas than in rural areas, and (4) Transpiration in urban areas were still higher in spite of stomatal restraint.

DOI： 10.3178/jjshwr.11.498

CiNii Books

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Language：Japanese   Publisher：土木学会  

DOI： 10.2208/jscej.1998.587_109

CiNii Books

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

A field observation was pertormed within and above a street canyon along a route 246 in summer 1996, to investigate the characteristics of heat balance of street canyon including the effect of transportation, and also to verify the forcing effect of vertical momentum exchange due to transportation. The following results were obtained; 1) anthropogenic heat due to transportation reached more than 200 (W/m&lt;sup&gt;2&lt;/sup&gt;), 2) temporal change of sensible heat was strongly affected by not only net radiation but also anthropogenic heat due to transportation, 3) latent heat was not negligible, 4) scintillation meter was available for measuring the sensible heat from street canyon, and 5) transportation gave the horizontal momentum to the surrounding atmosphere in the same direction as the traffic, so that the wind velocity and the vertical momentum exchange were modified by transportation especially in rush hours.

DOI： 10.2208/jscej.1998.587_109

CiNii Books

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Language：Japanese   Publisher：社団法人日本気象学会  

明治神宮で行われた集中観測データを森林環境気象モデルに同化させ, 神宮の森の気候緩和機能と大気浄化機能が定量的に評価された. その結果以下の結論が得られた. 1) 数点のポロメーター計測データから未知パラメータを非線形回帰させた気孔コンダクタンスモデルは, 気象学的測定から得られた群落気孔コンダクタンスの傾向をよく表現した. 2 )この気孔特性を森林環境気象モデル (NEO-SPAM2) に同化させて熱収支計算を行ったところ, 実測値を良好に再現した. 3) 神宮の森の気候緩和機能を大きく左右する植物の活性度 (気孔コンダクタンス) は, 樹冠部ほど大きく, 下方へ向かうほど減少している. また植物の活性度は午前中の早い時間帯に最も盛んであることが示された. 4) 本モデルを用いて, 神宮の森における汚染物質吸収量 (鉛直下向きフラックス) を算定したところ, その日中の平均値は, 観測結果と定量的によく一致した. またピーク時のNO_2フラックスを神宮の森全体の面積に換算すると, 乗用車93台分が排出するNO_2量に相当することが明らかとなった. 5 ) また汚染物質吸収は早朝に効率的に行われること, 樹冠付近の葉への吸収が活発なことなど, 観測で得られなかった大気浄化の時空間変動特性が示された.

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明治神宮の気候緩和機能・大気浄化機能を熱収支・汚染物質吸収量の観点から定量的に把握することを目的として1996年8月に集中観測を行い, 以下の成果が得られた. 1) 神宮の森の放射収支・熱収支が算定された. 正味放射量の約7割は蒸発潜熱に変換されており, 日中に神宮の森が放出する水分量は, 1秒あたり約150kg (ペットボトル100本分) に達する. また都市域の熱収支 (神田ほか, 1997) と比較することにより, 神宮の森の気候緩和機能が定量的に把握された. 2) ポロメーターにより計測される1枚の葉の蒸散・気孔コンダクタンスは, 計測地点の局所的な気象条件の影響を大きく受けるため, そのままでは群落全体の蒸散量に換算できないことが示された. 3) 晴天日の夕方の一般風が弱まる時間帯において, 0.5ms^&lt;-1&gt;以下の弱い森林吹き出し風の存在が示された. 4) 林冠上における汚染物質の鉛直下向きフラックスを傾度法を用いて算定したところ, 日中の平均値として, O_3は約0.30ppb ms^&lt;-1&gt;, NO_2は約0.11PPb ms^&lt;-1&gt;となり, 神宮の森による汚染物質吸収量が定量的に把握された. 5) 神宮の森で測定した汚染物質の濃度変動特性を検討した結果, 物質によりその挙動が異なった. 特にSPM濃度の日変化は夜間にピークをもち, 近接市街地とは逆の傾向を示す. これは夜間森林上に形成される安定層の影響であることが推察された.

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Language：Japanese   Publisher：水文・水資源学会  

DOI： 10.3178/jjshwr.10.329

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Publisher：Japan Society of Civil Engineers  

The object of this study is to develop a method for estimating both the ground thermometric parameter (ρ c λ) and ground conductive heat flux (G) simultaneously by using the ground surface temperature (Ts). This method is based on the Fourier series expressions of the result of heat transfer equation. The method is tested by a field-measurement. The following results are obtained: 1) The estimated ρ c λ have a reasonable value. 2) Estimated diurnal variations of G agree very well with that observed. 3) The spatial distribution of ρ c λ is also estimated from the surface temperature distribution obtained by the thermo-graphy.

DOI： 10.2208/prohe.41.1097

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Language：Japanese   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

The field observations were performed in Ginza office area in summer 1996, to investigate the characteristics of heat balance in complicated urban canopies. The sensible heat was measured by two methods, one was &quot;eddy correlation method&quot; and another was &quot;scintillation method&quot;. The following results were obtained; 1) The observed latent heat flux was very large and comparable to the sensible heat flux. This was proved to be caused by cooling systems introduced to office buildings. 2) The artificial and latent heat on a holiday were less than those on a weekday. 3) The sensible heat observed by scintillation technique agreed well with that by the eddy correlation method. And also, the longer measure ment path of scintillation meter (130m in this case) compared to that of sonic anemometer (only 15cm) could make the fluctuations smaller. 4) The displacement height (d) was found to be very sensitive to the results of scintillation methods and the way how to determine it was discussed.

DOI： 10.3178/jjshwr.10.329

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DOI： 10.3178/jjshwr.10.329

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The Heat Balance at Meiji-Shrine Forest, where is one of the largest green area in Tokyo Metropolitan, is observed by botha meteorological (MT) and a plant-physiological (PT) method. 70% of net radiation is distributed to latent heat flux. The diurnal variation of evaporation estimated by MT don&#039;t agree qualitatively with that by PT, because the latter is strongly affected by the local meteorological conditions of the sampling site. The characteristics of the stomatal conductance to meteorological conditions can be modeled well by Jarvis equation. The stomatal conductance modified by Jarvis model to exclude the local meteorological conditions, agree very qualitatively with the bulk stomatal conductance estimated by MT.

DOI： 10.2208/prohe.41.43

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The photochemical atmospheric pollution is a serious problem. Recently, it is said that biogenic hydrocarbons emitted from forests make some effects on the photochemical reactions, but it has not been confirmed because of the difficulty of measurement. We performed a field observation to estimate the balance of biogenic hydrocarbons, ozone and heat at a forest. The following results are obtained; 1) Ozone concentration over the forest is higher than that under the forest. 2) Biogenic hydrocarbons seems to be closely related to the ozone concentration through photochemical process. 3) The forest acts as a sink of ozone as a whole, but its magnitude is smaller than the ground surface.

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DOI： 10.2208/prohe.52.283

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DOI： 10.2208/prohe.52.259

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Language：Japanese   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

Rainfall interception (RI) over an outdoor urban scale model was investigated. On average, RI was 6% of the total rainfall and smaller than typical values in forests (10-50%). No correlation was found between RI and gross rainfall or rainfall duration unlike the correlations found in forests. RI was dependent on the saturation deficit at the beginning of the rainfall event. The latent heat for RI was approximately balanced by heat conduction from the concrete surfaces. Differences in the canopy structure are considered as possible reasons for the different behaviors of RI between the present site and forests. These differences in canopy structure include the area of the effective wet surface, the size of the roughness elements, and canopy heat capacity.

DOI： 10.11520/jshwr.21.0.34.0

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Language：Japanese   Publisher：Japan Society of Fluid Mechanics  

Particle image velocimetry (PIV) was applied to outdoor turbulent flow within and above urban scale model. This study shows the setup of the PIV system and some preliminary results. The PIV system achieved 60-min continuous measurements with the time resolution of 1/30 seconds for the section of 3x3 meters with the spatial resolution of 5cm. The 2 dimensional distribution of mean wind vector and turbulent statistics were successfully obtained. Also the PIV measurements were validated with measurements of ultrasonic anemometer which is conventional instrument for the investigation of atmospheric turbulence. Most of them showed good agreements within the error of 10%.

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This paper shows the seasonality of vertical profile of air temperature, CO_2, and H_2O within and above a suburban canopy and the turbulent diffusivity of the scalars. The results were derived from field measurements of the vertical profiles and fluxes, which were conducted in a residential area (the mean height of canopy is 7.3m) of Tokyo, Japan. The normalized turbulent diffusivity of air temperature and CO_2 depended on height and atmospheric stability, which is similar to that for vegetated canopies. In contrast, turbulent diffusivity of H_2O was relatively smaller than that of heat and CO_2. H_2O is not efficiently transferred probably because the source of H_2O is localized at the lowest level of urban canopy.

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Particle image velocimetry (PIV) was applied to outdoor turbulent flow within and above urban scale model. This study shows the setup of the PIV system and some preliminary results. The PIV system achieved 60-min continuous measurements with the time resolution of 1/30 seconds for the section of 3x3 meters with the spatial resolution of 5cm. The 2 dimensional distribution of mean wind vector and turbulent statistics were successfully obtained. Also the PIV measurements were validated with measurements of ultrasonic anemometer which is conventional instrument for the investigation of atmospheric turbulence. Most of them showed good agreements within the error of 10%.

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Language：Japanese   Publisher：Japan Society of Fluid Mechanics  

This paper shows the seasonality of vertical profile of air temperature, CO_2, and H_2O within and above a suburban canopy and the turbulent diffusivity of the scalars. The results were derived from field measurements of the vertical profiles and fluxes, which were conducted in a residential area (the mean height of canopy is 7.3m) of Tokyo, Japan. The normalized turbulent diffusivity of air temperature and CO_2 depended on height and atmospheric stability, which is similar to that for vegetated canopies. In contrast, turbulent diffusivity of H_2O was relatively smaller than that of heat and CO_2. H_2O is not efficiently transferred probably because the source of H_2O is localized at the lowest level of urban canopy.

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Language：Japanese   Publisher：日本流体力学会  

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Language：Japanese   Publisher：Japan Society of Fluid Mechanics  

DOI： 10.11426/nagare1982.26.91

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This paper shows the seasonal dependency of vertical profile of air temperature, CO<SUB>2</SUB>, and H<SUB>2</SUB>O within and above a suburban canopy and the turbulent diffusivity of the scalars. The results were derived from field measurements of the vertical profiles and fluxes, which were conducted in a residential area (the mean height of canopy is 7.3 m) of Tokyo, Japan. The vertical profile of CO<SUB>2</SUB> in the daytime drastically varied with the season; the CO<SUB>2</SUB> concentration within the canopy was lower than that above the canopy in summer but was slightly higher in winter. The seasonal change of the daytime CO<SUB>2</SUB> profile is likely due to the effect of photosynthesis by vegetation in backyards. The normalized turbulent diffusivity of air temperature and CO<SUB>2</SUB> depended on height and atmospheric stability, which is similar to that for vegetated canopies. In contrast, the normalized turbulent diffusivity of H<SUB>2</SUB>O was relatively smaller than that of heat and CO<SUB>2</SUB>. Although the correlation coefficients indicated that the transfer efficiencies of CO<SUB>2</SUB> were generally smaller than that of heat, the magnitude of normalized turbulent diffusivity of air temperature and CO<SUB>2</SUB> was almost same.

DOI： 10.2208/prohe.51.271

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The interception of rainfall was observed at an outdoor urban scale model site. The model dimensions were 50 x 100 m, with 1.5-m cubic roughness blocks arranged uniformly. The amounts of rainfall and runoff within the area of 6 x 6 m were measured. In this study, we introduced the specification of the facility and preliminary results of rain events which were obtained in September 2006. Mean rainfall intensity of the rainfall events ranged from 0.6 to 1.4 mm hour<SUP>-</SUP><SUP>1</SUP>. Under these rain events, the ratio of runoff to rainfall decreased as the rainfall decreased. This tendency was commonly found in both the total rainfall and the real-time rainfall intensity.

DOI： 10.2208/prohe.51.253

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Language：Japanese   Publisher：水文・水資源学会  

Rainfall interception was investigated at outdoor urban scale model (COSMO). The following results were obtained. 1) Runoff rate depends on the total amount of rainfall. The runoff rate increased and reached to unity with the increase of rainfall. The runoff rate also showed a seasonal dependency, with tending to be small in summer. 2) The amount of rainfall interception depended on water vapor deficit. A large water vapor deficit which was frequently observed in summer resulted in large rainfall interception. 3) Storage heat flux G was negative (heat was transferred from subsurface to surface) during rainfall. The large absolute value of G in summer would be one of the reasons for the large water vapor deficit during rainfall in summer.

DOI： 10.11520/jshwr.20.0.117.0

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Language：Japanese   Publisher：The Japan Society of Fluid Mechanics  

DOI： 10.11426/nagare1982.26.91

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Tokyo Bay, which is adjacent to Tokyo Metropolitan Area, has a significant influence on issues such as the heat island phenomenon and heavy rainfall. The impact of Tokyo Bay on these issues in relation to the Metropolitan Area may sometimes be attributed to the land-sea breeze mechanism. However, we have little information about diurnal variation of sea surface temperature (SST), the driving force of sea breeze. Water temperature gauges and thermometers were installed at 14 observation sites in Tokyo Bay since November 2006. From recent observations in winter, the following features were found: 1) SST at the mouth of bay is most of the time hotter than that at the head of bay; 2) SST at the mouth of bay is dependent on tidal fluctuation; 3) standard deviation of air temperature is frequently larger than that of SST. These results suggest that Tokyo Bay is influenced by ocean flow and air advection from the coastal land area.

DOI： 10.11520/jshwr.20.0.99.0

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DOI： 10.2208/prohe.50.493

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DOI： 10.2208/prohe.50.511

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DOI： 10.2208/prohe.50.445

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DOI： 10.2208/prohe.50.463

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Based on one year of field measurements, we described the annual fluxes of energy and CO<SUB>2</SUB> at a residential area of Tokyo. The major findings are as follows. 1) The total of <I>Rn</I>, <I>H</I>, and <I>LE</I> was 2.36, 1.35, and 0.90 GJ m<SUP>-2</SUP>, respectively. The latent heat flux <I>LE</I> was large despite the small areal fraction of natural coverage (trees and bare soil). The estimated local latent heat flux per unit natural coverage was two times larger than the available energy (<I>Rn</I>+<I>A</I>), which indicates that the ''oasis effect' was significant. 2) The annual CO<SUB>2</SUB> flux was upward due to fossil fuel consumption in houses and traffic and human bodily exhalations. The total CO<SUB>2</SUB> flux was 3352 gC m<SUP>-2</SUP> and was six times larger than the downward CO<SUB>2</SUB> flux at a typical temperate deciduous forest.

DOI： 10.2208/prohe.49.361

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This study concerns the build-up of CO&lt;SUB&gt;2&lt;/SUB&gt; within a suburban canopy under nocturnal stably stratified conditions. The results were derived from wintertime field measurements of the vertical profiles of CO&lt;SUB&gt;2&lt;/SUB&gt;, air temperature, and turbulent flows. We examined the ensemble mean vertical profiles using the bulk Richardson number (Rb). Under stable conditions (Rb&gt;5), the high CO&lt;SUB&gt;2&lt;/SUB&gt; concentration within the canopy stayed at almost the same level, which indicates that the CO&lt;SUB&gt;2&lt;/SUB&gt; emitted from the houses accumulated within the canopy. Such behavior was not found in the H&lt;SUB&gt;2&lt;/SUB&gt;O profile. We argue that these profiles are influenced by subsiding cold air from the rooftop, thus drawing the high CO&lt;SUB&gt;2&lt;/SUB&gt; levels from ventilation fans down towards the ground.

DOI： 10.11520/jshwr.18.0.113.0

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Although many researchers have studied the atmospheric heat environment in urban area (ex. Heat island), but the studies focusing on the thermal effect to hydrosphere drained from urban area are few.We observed both the flow rate and temperature of sewage in a residential area to investigate the thermal transport through sewage network.On the basis of annual data set, the following results were obtained.(1) The diurnal pattern of sewage flow rate is influenced by the inflow of groundwater.(2) Groundwater is also found to influence on the sewage field temperature.(3) The used water temperature is estimated based on mass and heat balance equation.(4) Anthropogenic heat added in residential area is estimated from the difference between supplied water and used water temperature.

DOI： 10.11520/jshwr.18.0.117.0

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The existence of Tokyo Bay would have great impacts on the atmospheric issues in Tokyo metropolitan area, such as heat island phenomenon, heavy rainfall, and air pollution. In this study, we constructed an observation system at Tokyo Bay to measure the energy and CO&lt;SUB&gt;2&lt;/SUB&gt; fluxes between water surface and the atmosphere, and compare the fluxes with those at a suburban area in Tokyo. From recent observations in winter, we found the following interesting features of energy and CO&lt;SUB&gt;2&lt;/SUB&gt; fluxes in Tokyo Bay. 1) The latent heat flux (LE) was larger than expected and it increased with wind speed, whereas LE at the residential area varied with solar radiation forcing. 2) The CO&lt;SUB&gt;2&lt;/SUB&gt; flux in the urban area was positive (CO&lt;SUB&gt;2&lt;/SUB&gt; source), whereas that in Tokyo Bay was negative (Tokyo Bay acted as CO&lt;SUB&gt;2&lt;/SUB&gt; sink). 3) Sensible heat flux had daily variation corresponding to the variability of surface and air temperatures.

DOI： 10.11520/jshwr.18.0.114.0

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DOI： 10.2208/prohe.48.139

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DOI： 10.2208/prohe.48.175

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DOI： 10.2208/prohe.48.607

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DOI： 10.2208/prohe.48.163

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DOI： 10.5359/jawe.2003.97_13

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DOI： 10.5359/jawe.2003.97_13

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DOI： 10.5359/jawe.2003.97_13

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DOI： 10.2208/prohe.47.1

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In this paper, we evaluate the applicability of flux-gradient relationships for momentum and heat for urban boundary layers within the Monin-Obukhov similarity (MOS) theory framework. Although the theory is widely used for smooth wall boundary layers, it is not known how well the theory works for urban layers. To address this problem, wemeasured the vertical profiles of wind velocity, air temperature, and fluxes of heat and momentum over a residential area and compared the results to theory. We found the following: (1) The non-dimensional horizontal wind speed has good agreement with the stratified logarithmic profile predicted using the semi-empirical Monin-Obukov similarity (MOS) function, when it was scaled by the surface friction velocity that is derived from the shear stress extrapolated to the roof-top level. (2) The scaled gradient of horizontal windspeed followed a conventional semiempirical function for a flat surface above the canopy, whereas, in the vicinity of the canopy height it was larger than the commonly-used empirical relationship. (3) The potential temperature profile above the canopy shows dependency on the atmospheric stability and the scaled gradient of temperature is in good agreement with a conventional shear function for heat. In the case of heat, the dependency on height was not found. (4) The flux-gradient relationship for momentumand heat was rather similar to that for flat surfaces than that for vegetated canopies.

DOI： 10.11520/jshwr.16.0.262.0

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The seasonal trend of vertical temperature profiles within and above an urban canopy has been investigated. We measured air temperatures and wind velocities along a 29-m tower in a residential area of Tokyo, Japan continually for 14 months. The height of the daily maximum temperature ZTmax varied with the season; ZTmax was at the roof level in winter but near the ground in summer. The seasonal change of ZTmax is likely due to the change of height at which solar energy is absorbed. At the time of the maximum temperature, the atmosphere above the canopy is always unstable whereas the air within the canopy is unstable in summer but stable in winter.

DOI： 10.11520/jshwr.16.0.260.0

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Large-eddy simulations have been performed for fully developed turbulent flow within and above explicitly resolved simple cube arrays. The results from our model, hereafter LES-CITY, are shown to agree with laboratory experiments. We investigated the systematic influence of cube density on turbulent flow characteristics by performing numerical experiments for cube areal densitiesfrom 0 to 44%. The following results were obtained: (1) The dispersive momentum flux was quite large within the canopy layer due to a mean stream re-circulation, whereas it was smaller above thecanopy. The spatial variation of temporally averaged momentum in the roughness sub-layer was 20% or less of the total kinematic surface drag. (2) The temporally and spatially-averaged flow structure confirmed the existence of conventionally described canyon flow regimes; isolated, interfacial, and wake. However, the intermittency of the canyon flow for all cube densities was quite large and the stream patterns were never persistent. (3) Turbulent organized structures (TOS) similar to those observed in turbulent surface-layer flows were simulated, which are characterized by longitudinallyelongated low speed streaks and the corresponding shorter streamwise vortices. The streaks in sparse and dense canopy flows were likely to be aligned to the street line and to the roof lines, respectively. Such heterogeneity of TOS partially accounts for the large spatial variation of momentum flux. (4) In contrast to the mixing layer analogy of vegetation flows, the TOS and the resulting turbulent statistics of urban flow above the canopy resembled those in surface layers. The recirculation withinthe canopy significantly influenced the turbulent statistical properties.

DOI： 10.11520/jshwr.16.0.266.0

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A long-term field measurement is performed to investigate turbulent transfers in a densely built-up urban surface layer. The ratios of fluxes measured at two heights are almost unity. We can expect the existence of the surface layer in this residential area. The turbulent transfer efficiencies of momentum, heat, vapor, and CO_2 are examined. Following results are obtained; 1) The ratio for heat/momentum is smaller the results in Kansas experiment. This behavior is expected over an urban surface where form drag due to bluff-body effects of buildings increases the transfer efficiency of momentum compared to scalar transfers. 2) The transfer efficiencies of vapor and CO_2 are smaller than that of heat. 3) Wavelet analysis shows this reason. Thermal structures and organized structures transfer heat efficiently. Vapor and CO_2 are also transferred as well as heat by some structures. But they are not or adversely transferred by other structures.

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Language：Japanese   Publisher：東京工業大学工学部土木工学科  

CiNii Books

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Language：Japanese   Publisher：東京工業大学工学部土木工学科  

CiNii Books

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Language：Japanese   Publisher：日本流体力学会  

A long-term field measurement is performed to investigate turbulent transfers in a densely built-up urban surface layer. The ratios of fluxes measured at two heights are almost unity. We can expect the existence of the surface layer in this residential area. The turbulent transfer efficiencies of momentum, heat, vapor, and CO_2 are examined. Following results are obtained; 1) The ratio for heat/momentum is smaller the results in Kansas experiment. This behavior is expected over an urban surface where form drag due to bluff-body effects of buildings increases the transfer efficiency of momentum compared to scalar transfers. 2) The transfer efficiencies of vapor and CO_2 are smaller than that of heat. 3) Wavelet analysis shows this reason. Thermal structures and organized structures transfer heat efficiently. Vapor and CO_2 are also transferred as well as heat by some structures. But they are not or adversely transferred by other structures.

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Language：Japanese  

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DOI： 10.2208/prohe.46.79

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DOI： 10.2208/prohe.46.91

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Language：English   Publisher：AMER METEOROLOGICAL SOCIETY  

Web of Science

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Language：Japanese   Publisher：水文・水資源学会  

DOI： 10.11520/jshwr.15.0.204.0

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Language：Japanese   Publisher：東京工業大学工学部土木工学科  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The present study uses observational data from a residential site in Tokyo, Japan and a rice paddy in Chiba Pref., Japan, to investigate the relative facility with heat, water vapor, and carbon dioxide are transported by turbulence in the surface layer. The ratios of linear correlation coefficients |rwT/ruw| and |rwq/ruw| increase with stability and the ratios at residential area are generally smaller than at rice paddy due to bluff-body effects. At rice paddy, the ratios of linear correlation coefficient |rwc/rwq| is generally smaller than unity. Meanwhile at the residential area, the distribution of the ratio |rwc/rwq| scatters to |z'/L|. This inequality may be caused by the complex source patterns of the urban surface and the vertical profile within the canopy. Inequalities of transfer between T, c, and q will imply that the diffusion coefficient between them have different value respectively.

DOI： 10.2208/prohe.45.253

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study demonstrates the numerical prediction of thermal sensation index for outdoor environment (SET*OUT) using Regional Atmospheric Modeling System (RAMS). SET*OUT, one of the major thermal sensation index, requires data sets of wind velocity, absolute humidity, air temperature and each component of short wave and long wave radiation in both upward and downward directions. Temporal and spatial variation of SET*OUT over the Kanto Region on August 10 1998 has been presented and discussed. The thermal sensation index for indoor environment (SET*IN) is referred to as a comparison. It is found that the variation of SET*OUT is strongly influenced by mean radiation temperature and sea breeze penetration. The mean radiation temperature, and consequently SET*OUT, have distinctive double peaks in the morning and the afternoon due to the shape factor of cylindrical human body for direct solar radiation. The first peak of SET*OUT in the morning roughly corresponds to the arrival of sea breeze front, and the value is generally larger than that of the second peak in the afternoon. Such a behavior of SET*OUT can be accounted for by the fact that the sea breeze increases wind velocity and activate the heat transfer from human body. SET*IN is similar to but slightly (0.5-1°C) larger than air temperature, which is due to the high humidity condition in Tokyo area.

DOI： 10.2208/prohe.45.259

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This study uses observational data from urban sites in Setagaya, Vancouver and Ginza, to investigate the applicability of conventional Monin-Obukhov similarity functions.The following results are obtained;(1)The ration of linear correlation coefficients of heat and momentum transfer are generally smaller than conventional values in rural sites due to bluff body effect.(2)Non-dimensional form of (a) standard deviations of velocity, (b)standard deviation of temperature, (c) dissipation ration of temperature variances, and (d) dissipation ration of kinetic energy, as a function of stability paramenter, are proposed.All of these also show more or less different curves from conventional relationships in rural sites.

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Language：Japanese   Publisher：日本流体力学会  

Field observation and numerical simulations were performed to investigate the atmospheric structure and distribution of air pollutants over Tokyo Bay. The following results were obtained : 1) Observed diurnal variation of potential temperature over Tokyo Bay is different from over the land or the sea. 2) There is a descending flow over Tokyo Bay. and it is the compensation for the divergent flow pattern. The peak value of descending flow exits at the height of 300-500m. 3) The rise in potential temperature in the daytime is caused by the adiabatic heating of descending flow. 4) Vertical gradient of CO_2 is positive over the bay. It suggests that CO_2 is transported over Tokyo Bay from surrounding high emission area.

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Field observations to investigate area-averaged turbulence characteristics were performed in a densely built-up residential neighborhood in Tokyo, Japan.Besides eddy-correlation sensors, a scintillometer was used in an urban environment.Several important results are summarized as follows : (1) Radiation balance and energy balance of observation area are obtained.(2) A new technique which uses simultaneous scintillation measurements at two heights is developed to estimate directly both area-averaged zero-plain displacement height Z_d and heat flux Q_H.The estimated Z_d is found to be slightly dependent on the atmospheric stability parameter (lower Z_d under more unstable conditions).(3) Source areas for the scintillometer are 2-3 times larger than those for the eddy correlation sensors under unstable conditions.30-min averaged, normalized standard deviations of Q_H measured by the two methods are compared. Whilst Q_H estimates agree well, their short time variability was generally larger for the eddy-correlation as compared with the scintillometer data under wide range of stability conditions.This result can be attributed to the superior spatial integration due to the longer averaging path (250 m) of the scintillometer.It is concluded that time-averaging requirements to obtain representative flux measurement for scintil-lometer applications can be relaxed.

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DOI： 10.2208/prohe.44.79

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DOI： 10.11426/nagare1982.18.101

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Language：Japanese   Publisher：日本流体力学会  

DOI： 10.11426/nagare1982.18.101

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Language：Japanese   Publisher：東京工業大学工学部土木工学科  

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DOI： 10.2208/prohe.43.91

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Language：Japanese  

DOI： 10.2208/prohe.43.233

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Language：Japanese   Publisher：The Japan Society of Fluid Mechanics  

DOI： 10.11426/nagare1982.18.101

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Language：Japanese   Publisher：東京工業大学工学部土木工学科  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The Heat Balance at Meiji-Shrine Forest, where is one of the largest green area in Tokyo Metropolitan, is observed by botha meteorological (MT) and a plant-physiological (PT) method. 70% of net radiation is distributed to latent heat flux. The diurnal variation of evaporation estimated by MT don't agree qualitatively with that by PT, because the latter is strongly affected by the local meteorological conditions of the sampling site. The characteristics of the stomatal conductance to meteorological conditions can be modeled well by Jarvis equation. The stomatal conductance modified by Jarvis model to exclude the local meteorological conditions, agree very qualitatively with the bulk stomatal conductance estimated by MT.

DOI： 10.2208/prohe.41.43

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Language：Japanese   Publisher：東京工業大学工学部土木工学科  

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