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DOI： 10.1007/s10546-010-9477-0

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Language：English  

Sea surface temperature (SST) and air temperature were measured in situ in Tokyo Bay. These measurements were made with high spatial and temporal resolutions between November 2006 and September 2007. The analysis of these data revealed 1) the seasonal and diurnal variations of SST and air temperature, and 2) the physical process by which Tokyo Bay lowers urban air temperature in summer. The following were the major findings obtained: 1) the diurnal amplitude of SST was as large as 5.5°C
2) abrupt increases of SST occurred at the head and mouth of the bay that were due to heated water discharge and the Kuroshio, respectively
3) the values of the satellite-based objectively analyzed SSTs were higher than those of the in situ SSTs, especially in winter
4) the relationship between SST and air temperature was classified into three seasonal modes-winter, transient, and summer-and each mode was associated with the seasonal stability condition of the near-surface water
5) the strong southwesterly wind over the bay in summer decreased the SST mainly because of increased turbulent mixing at the water surface, thereby increasing downward sensible heat flux up to-100W m-2
6) the lower SSTs in summer lowered the air temperature, but only for the urban atmosphere near the coast, and no effect was detected at 20 km inland
and 7) the horizontal gradient of air temperature over the land intensified with increasing wind speed. © 2009 American Meteorological Society.

DOI： 10.1175/2009JAMC2163.1

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Language：English   Publisher：AMER METEOROLOGICAL SOC  

Sea surface temperature (SST) and air temperature were measured in situ in Tokyo Bay. These measurements were made with high spatial and temporal resolutions between November 2006 and September 2007. The analysis of these data revealed 1) the seasonal and diurnal variations of SST and air temperature, and 2) the physical process by which Tokyo Bay lowers urban air temperature in summer. The following were the major findings obtained: 1) the diurnal amplitude of SST was as large as 5.5 degrees C; 2) abrupt increases of SST occurred at the head and mouth of the bay that were due to heated water discharge and the Kuroshio, respectively; 3) the values of the satellite-based objectively analyzed SSTs were higher than those of the in situ SSTs, especially in winter; 4) the relationship between SST and air temperature was classified into three seasonal modes-winter, transient, and summer-and each mode was associated with the seasonal stability condition of the near-surface water; 5) the strong southwesterly wind over the bay in summer decreased the SST mainly because of increased turbulent mixing at the water surface, thereby increasing downward sensible heat flux up to -100 W m(-2); 6) the lower SSTs in summer lowered the air temperature, but only for the urban atmosphere near the coast, and no effect was detected at 20 km inland; and 7) the horizontal gradient of air temperature over the land intensified with increasing wind speed.

DOI： 10.1175/2009JAMC2163.1

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Language：English   Publisher：METEOROLOGICAL SOC JAPAN  

Characteristics of a flow in the boundary layer over a sequence of small localized urban canopies with various heights were studied by wind-tunnel experiment under neutral stratification, where "small" means that the length (fetch) is insufficient for the flow to fully adapt to the surface geometry. The sequence was composed of two taller building groups, such as commercial buildings, and two roughness areas of lower obstacles, such as houses. In the sequence, the flow passed over boundaries from the building groups to the roughness areas, named downward boundaries, and boundaries from the roughness areas to the building groups, named upward boundaries. The flow was quite different depending on the boundary types. The focus was placed on equilibrium-like states of the flow and it was found that the flow behind the boundaries were in the states in short fetches.
Relating to the downward boundary, flow over the roughness areas was obtained in the range L/H = 7.5 to 63, where H is the height of the upstream array and L is the distance from the end of the upstream array to the measurement position. It was found that the profiles of the Reynolds stress exhibited double-layered structure separated by kinks. In the range L/H > 19, the profiles had constant forms above the kinks and the flow was in some sort of equilibrium state. It was discussed schematically and found that the double-layered structure was explained well based on the three sources of turbulence: turbulence transported from the flow over the upstream building group, turbulence caused by the downward boundary, and turbulence caused by the surface obstacles.
Relating to the upward boundary, flow over the building group (cubic array with a frontal area index of 0.25) was obtained. Two adaptation processes to equilibrium state were found: adaptation of transversal average of the streamwise velocity (U) and adaptation of transversal shear of U. The latter was in balanced state in shorter fetch than the former.

DOI： 10.2151/jmsj.87.705

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Language：English   Publisher：SPRINGER  

Momentum and heat transfer was examined for the urban-like surfaces used within the Comprehensive Outdoor Scale MOdel (COSMO) experiments. Simultaneous and comparative meteorological measurements were made over a pair of scale models with different block geometries. These data were analyzed to investigate the influence of height variations, obstacle elongation, and packing density, lambda (p) , of blocks on the aerodynamic properties. In addition, the robustness of theoretical expressions of bulk transfer coefficients for momentum and heat with respect to geometric parameters was examined. Our analyses showed: (1) the theoretical framework for the bulk transfer coefficient for momentum, C (m) , and that for heat, C (h) , was applicable for homogeneous building arrays, (2) the sensitivity of C (h) to the surface geometry was smaller than that of C (m) , (3) the transfer coefficients were increased by variations of block heights, but not by elongation of blocks, (4) first-order approximations of C (m) and C (h) for an array of blocks with two different heights can be made by applying simple theoretical assumptions to include the effects of height variation, and (5) variations of block heights increased the momentum flux significantly, but caused little change in the sensible heat flux. This can be explained by the feedback mechanism of aerodynamic- thermal interaction; aerodynamic mixing decreased both the advective velocity and the vertical temperature gradient.

DOI： 10.1007/s10546-009-9381-7

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Language：English   Publisher：AMER METEOROLOGICAL SOC  

The authors' objective was to apply the Simple Urban Energy Balance Model for Mesoscale Simulation (SUMM) to cities. Data were selected from 1-yr flux observations conducted at three sites in two cities: one site in Kugahara, Japan (Ku), and two sites in Basel, Switzerland (U1 and U2). A simple vegetation scheme was implemented in SUMM to apply the model to vegetated cities, and the surface energy balance and radiative temperature T(R) were evaluated. SUMM generally reproduced seasonal and diurnal trends of surface energy balance and T(R) at Ku and U2, whereas relatively large errors were obtained for the daytime results of sensible heat flux Q(H) and heat storage Delta Q(S) at U1. Overall, daytime underestimations of Q(H) and overestimations of Delta Q(S) and T(R) were common. These errors were partly induced by the poor parameterization of the natural logarithm of the ratio of roughness length for momentum to heat (kappa B(-1)); that is, the observed kappa B(-1) values at vegetated cities were smaller than the simulated values. The authors proposed a new equation for predicting this coefficient. This equation accounts for the existence of vegetation and improves the common errors described above. With the modified formula for kappa B(-1), simulated net all-wave radiation and T(R) agreed well with observed values, regardless of site and season. However, at U1, simulated Q(H) and Delta Q(S) were still overestimated and underestimated, respectively, relative to observed values.

DOI： 10.1175/2008JAMC1891.1

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Language：English   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   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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Language：English   Publisher：CAMBRIDGE UNIV PRESS  

The main objective of this study is to examine the robustness of the inner-layer scaling similarity of near-wall turbulence. The turbulent boundary layer of interest is over a very rough surface with a very high Reynolds number and significant outer-layer disturbances. This is not consistent with the canonical turbulent flows studied in laboratories, but it is common in urban areas. The investigation was conducted using the comprehensive outdoor scale model (COSMO) facility. COSMO is composed of a regular array of 1.5 m concrete cubes on a 50 x 100 m(2) flat concrete base. This unique facility allows us to obtain the turbulent dataset within the vertical constant stress region under near-neutral stratification at high Reynolds numbers. The turbulent spectra and the standard deviation of velocity fluctuations from COSMO were compared with the values obtained over rural and urban surfaces, and in wind-tunnel experiments.
The results confirmed that the inner-layer scaling similarity was robust for the wall-normal fluctuations and the Reynolds stress, independent of the roughness types and the outer-layer conditions. The inner-layer scaling similarity failed for the horizontal velocity fluctuations owing to the influence of the outer-layer disturbance. The relative importance of outer-layer turbulence to inner-layer-scale eddies in the horizontal velocity fluctuations was successfully quantified in terms of the roughness scale normalized by the outer-layer scale.

DOI： 10.1017/S0022112008003765

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DOI： 10.2208/prohe.52.259

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DOI： 10.2208/prohe.52.253

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DOI： 10.2208/prohe.52.307

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DOI： 10.2208/prohe.52.313

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DOI： 10.2208/prohe.52.283

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DOI： 10.5359/jawe.2008.299

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Language：English   Publisher：JOHN WILEY & SONS LTD  

The objectives of our study are (1) to evaluate the simple urban energy balance model for mesoscale simulation (SUMM) using such data that are free from many real world uncertainties in respect to spatial variability in material, geometry, and land use, and (2) to analyse the sensitivity of land surface parameters (LSP), which are used in the model. The model was evaluated using the data obtained from comprehensive outdoor scale-model (COSMO) experiments during a period, which, covers roughly half of a year (winter and spring-early summer) including various wind conditions. SUMM simulated surface layer energy fluxes, surface temperature, and interior temperature fairly well under windy conditions while it underestimated sensible heat flux under calm conditions. On average, simulated sensible heat flux underestimated observed value by 30% (0.73 MJ m(-2) d(-1)) in daytime. Errors of net radiation (4%; 0.40 MJ m(-2) d(-1)) and heat storage (5%; 0.33 MJ m(-2) d(-1)) were smaller than that of sensible heat flux in daytime. This underestimation of sensible heat flux can be attributed to the inadequate parameterization of the surface layer bulk transfer coefficient used in SUMM under calm conditions. On the basis of the sensitivity analyses, parameterization of the surface layer bulk transfer coefficient using Monin-Obukhov similarity theory (MOST) shows that the model performance is very sensitive to this coefficient, while it is less sensitive to the relative Values of the bulk transfer coefficients of local faces. Copyright (c) 2007 Royal Meteorological Society.

DOI： 10.1002/joc.1624

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：METEOROLOGICAL SOC JPN  

This paper reviews the progress made in urban meteorology over the past few decades. The focus is on the impact of urban surfaces on the overlying atmosphere along the conventional meteorological frameworks. Section I details the difficulties in generalizing urban surfaces in a meteorological sense because of surface diversity, and considers whether conventional similarity law is applicable. Section 2 describes the characteristics of urban surfaces as the bottom boundary of the atmosphere and includes a discussion of land surface parameters and the resultant surface energy partitioning. Section 3 explains characteristics of the urban atmosphere, including temperature fields, local circulations and rainfall. Section 4 describes recent progress in. numerical modeling and promising new technologies, thus revealing a possible future direction for urban meteorological studies.

DOI： 10.2151/jmsj.85B.363

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Language：English   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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Language：English   Publisher：SPRINGER  

A large-eddy simulation (LES) study is presented that investigates the spatial variability of temporal eddy covariance fluxes and the systematic underestimation of representative fluxes linked to them. It extends a prior numerical study by performing high resolution simulations that allow for virtual measurements down to 20 m in a convective boundary layer, so that conditions for small tower measurement sites can be analysed. It accounts for different convective regimes as the wind speed and the near-surface heat flux are varied. Moreover, it is the first LES imbalance study that extends to the stable boundary layer. It reveals shortcomings of single site measurements and the necessity of using horizontally-distributed observation networks. The imbalances in the convective case are attributed to a locally non-vanishing mean vertical advection due to turbulent organised structures (TOS). The strength of the TOS and thus the imbalance magnitude depends on height, the horizontal mean wind and the convection type. Contrary to the results of a prior study, TOS cannot generally be responsible for large energy imbalances: at low observation heights (corresponding to small towers and near-surface energy balance stations) the TOS related imbalances are generally about one order of magnitude smaller than those in field experiments. However, TOS may cause large imbalances at large towers not only in the case of cellular convection and low wind speeds, as found in the previous study, but also in the case of roll convection at large wind speeds.
In the stably stratified boundary layer for all observation heights neither TOS nor significant imbalances are observed.
Attempting to reduce imbalances in convective situations by applying the conventional linear detrending method increases the systematic flux underestimation. Thus, a new filter method is proposed.

DOI： 10.1007/s10546-006-9133-x

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Language：Japanese   Publisher：The Japan Society of Fluid Mechanics  

DOI： 10.11426/nagare1982.26.361

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：Meteorological Society of Japan  

This paper reviews the progress made in urban meteorology over the past few decades. The focus is on the impact of urban surfaces on the overlying atmosphere along the conventional meteorological frameworks. Section 1 details the difficulties in generalizing urban surfaces in a meteorological sense because of surface diversity, and considers whether conventional similarity law is applicable. Section 2 describes the characteristics of urban surfaces as the bottom boundary of the atmosphere and includes a discussion of land surface parameters and the resultant surface energy partitioning. Section 3 explains characteristics of the urban atmosphere, including temperature fields, local circulations and rainfall. Section 4 describes recent progress in numerical modeling and promising new technologies, thus revealing a possible future direction for urban meteorological studies. © 2007, Meteorological Society of Japan.

DOI： 10.2151/jmsj.85B.363

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Language：English   Publisher：Japan Society of Civil Engineers  

This paper reports on the evaluation of Simple Urban Energy Balance for Mesoscale Simulation (SUMM) to two cities (i. e. Kugahara, Japan; Basel, Switzerland) in winter, spring and summer. This new version of SUMM is incorporated with vegetation scheme to meet the existence of vegetation fraction in real city. SUMM simulated the urban energy balance and radiative temperature (Tr) generally well in Kugahara and Basel. However, SUMM slightly underestimated Tr in the nighttime and overestimated Tr in the daytime in Basel.

DOI： 10.2208/prohe.51.259

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Publisher：Japan Society of Civil Engineers  

This paper shows the seasonal dependency of vertical profile of air temperature, CO₂, and H₂O 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 CO₂ in the daytime drastically varied with the season; the CO₂ 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 CO₂ profile is likely due to the effect of photosynthesis by vegetation in backyards. The normalized turbulent diffusivity of air temperature and CO₂ depended on height and atmospheric stability, which is similar to that for vegetated canopies. In contrast, the normalized turbulent diffusivity of H₂O was relatively smaller than that of heat and CO₂. Although the correlation coefficients indicated that the transfer efficiencies of CO₂ were generally smaller than that of heat, the magnitude of normalized turbulent diffusivity of air temperature and CO₂ was almost same.

DOI： 10.2208/prohe.51.271

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Language：English  

CiNii Books

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Language：English   Publisher：Japan Society of Civil Engineers  

This paper reports on the evaluation of Simple Urban Energy Balance for Mesoscale Simulation (SUMM) to two cities (i. e. Kugahara, Japan; Basel, Switzerland) in winter, spring and summer. This new version of SUMM is incorporated with vegetation scheme to meet the existence of vegetation fraction in real city. SUMM simulated the urban energy balance and radiative temperature (Tr) generally well in Kugahara and Basel. However, SUMM slightly underestimated Tr in the nighttime and overestimated Tr in the daytime in Basel.

DOI： 10.2208/prohe.51.259

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Publisher：Japan Society of Civil Engineers  

The present study investigated the vertical profiles of the turbulent statistics over the reduced urban scale model in a neutral stratification. The experiment was conducted under the planetary boundary layer so that the corrected data was always affected by the outer layer turbulence more or less. We compared the surface layer turbulence statistics in the scale model with that in urban, which are velocity spectra, momentum co-spectra and nondimensional velocity variances and so on. <BR>A scale effect was apparent in the statistics related with the horizontal velocity variance. The scale effect came from the discrepancy of the ratio of outer layer (i. e. planetary boundary layer) scale with the surface layer scale of the scale model and with that of urban. Although the former scale is always same order, the latter scale is different in urban and in the scale model. Therefore we considered that the scale effect is an evidence of the influence of the outer layer turbulence in the surface layer.

DOI： 10.2208/prohe.51.247

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Publisher：Japan Society of Civil Engineers  

Datasets of energy fluxes and surface temperature were obtained from Comprehensive Outdoor Scale Model Experiment (COSMO) in winter and spring-early summer. Daytime and daily total statistics of the ratio of heat storage (dQs) to net all-wave radiation (Q*) were investigated. We obtained following major findings. i) Daytime (Q* ≥ 0) dQs/Q* in winter were larger than those of spring-early summer. ii) Daytime dQs/Q* was slightly dependent on wind velocity and decreased with increasing wind velocity. iii) Daily total dQs/Q* was negative in winter and positive in summer, since daily total Q* was positive regardless of seasons while daily total dQs was negative in winter and positive in summer. The value of daily total dQs was strongly related to net daily increment of surface temperature.

DOI： 10.2208/prohe.51.265

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DOI： 10.2208/prohe.51.253

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Publisher：Japan Society of Civil Engineers  

Turbulent organized structure (TOS) above urban canopies has not been clarified. In order to investigate it, we observed the horizontal distribution of TOS at COSMO (Comprehensive Outdoor Scale Model experiment for urban climate). The horizontal dimension of COSMO was 50m x 100m, with 1.5m cubic roughness blocks arranged uniformly. 60 thermo couples and 8 sonic anemometers were arranged. <BR>A new quantitative analysis to characterize the size of TOS has been conducted by using OSIM (Organized Structure Identification Method). OSIM detects the area of large turbulent motion and quantified the span-wise width and the time duration of the motion. In this study, we explained the algorithm of OSIM and applied it to COSMO data.

DOI： 10.2208/prohe.51.241

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Language：English  

CiNii Books

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Language：Japanese  

DOI： 10.3178/jjshwr.20.25

CiNii Books

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Language：English   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.

DOI： 10.2151/jmsj.84.1063

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Language：English  

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, kBT -1, had an average value of 7. This value of kBT-1 was larger than those documented for vegetated and agricultural surfaces, but less than that reported for a light industrial area. In winter, kBT-1 tended to be smaller, suggesting dependence on the vertical position of the heat source within the canopy. The kBT-1 results also showed a diurnal change, in which higher values occurred in the afternoon. The parameter kBq-1, the ratio of the roughness length of momentum to water vapor, ranged from 40 to 600. The parameter kBq-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, β, ranged from 0.02 to 0.3. β gradually decreased with the number of elapsed days after precipitation. © 2006, Meteorological Society of Japan.

DOI： 10.2151/jmsj.84.1063

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Language：English   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  

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. © Springer 2005.

DOI： 10.1007/s10546-005-9034-4

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Language：English   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   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：Book review, literature introduction, etc.   Publisher：SPRINGER WIEN  

This paper describes progress made in the scale modeling Of urban climate. The Studies reviewed are mainly indoor and outdoor experiments that use an array of urban-like flow obstacles or roughness elements such as cubes, blocks, and cylinders. Except for several important and unique Studies, the many experiments that use a single Obstacle, or those that use an array of elements to create a vegetation-like roughness are excluded from this review. Topics considered include turbulent flow, scalar dispersion, local transfer coefficient, radiative transfer, and the Surface energy balance. More than 40 relevant Studies are cited, and both significant developments and remaining problems are described. The future application of scale models to obtain a comprehensive understanding of urban climate is also examined, with the focus mainly upon the possibility Of outdoor experiments.

DOI： 10.1007/s00704-005-0141-4

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Language：English   Publisher：SPRINGER WIEN  

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, we measured the vertical profiles of wind velocity, air temperature, and fluxes of heat and momentum over a residential area and compared the results to theory. The measurements were clone above an urban canopy whose mean height z(h) is 7.3 m. 3-D sonic anemometers and fine wire thermocouples were installed at 4 heights in the region 1.5z(h), &lt; z &lt; 4z(h). We found the following: (1) The non-dimensional horizontal wind speed hits 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 wind speed (dU/dz)kz '/u(*) followed a conventional semi-empirical function for a flat Surface at a level (z/z(h) = 2.9), whereas, in the vicinity of the canopy height phi(-1)(M) was larger than the commonly-used empirical relationship. (3) The potential temperature profile above the canopy shows dependency oil the atmospheric stability and the scaled gradient of temperature (phi(H) = (d theta/dz)kz '/T-*) is in good agreement with a conventional Shear function for heat. In the case of heat, the dependency oil height was not found. (4) The flux-radient relationship for momentum, Will and heat in the region 1.5z(h) &lt; z &lt; 4z(h) was rather similar to that for flat Surfaces than that for vegetated canopies.

DOI： 10.1007/s00704-005-0150-3

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Language：English   Publisher：SPRINGER  

Turbulent organized structures (TOS) above building arrays were investigated using a large-eddy simulation (LES) model for a city (LES-CITY). Square and staggered building arrays produced contrasting behaviour in terms of turbulence that roughly corresponded to the conventional classification of 'D-type' and 'K-type' roughness, respectively: (1) The drag coefficients (referred to the building height) for staggered arrays were sensitive to building area density, but those for square arrays were not. (2) The relative contributions of ejections to sweeps (S-2/S-4) at the building height for square arrays were sensitive to building area density and nearly equalled or exceeded 1.0 (ejection dominant), but those for staggered arrays were insensitive to building area density and were mostly below 1.0 (sweep dominant). (3) Streaky patterns of longitudinal low speed regions (i.e., low speed streaks) existed in all flows regardless of array type. Height variations of the buildings in the square array drastically increased the drag coefficient and modified the turbulent flow structures. The mechanism of D-type and K-type urban-like roughness flows and the difference from vegetation flows are discussed. Although urban-like roughness flows exhibited mixed properties of mixing layers and flat-wall boundary layers as far as S-2/S-4 was concerned, the turbulent organized structures of urban-like roughness flows resembled those of flat-wall boundary layers.

DOI： 10.1007/s10546-005-5294-2

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Language：English  

Turbulent organized structures (TOS) above building arrays were investigated using a large-eddy simulation (LES) model for a city (LES-CITY). Square and staggered building arrays produced contrasting behaviour in terms of turbulence that roughly corresponded to the conventional classification of 'D-type' and 'K-type' roughness, respectively: (1) The drag coefficients (referred to the building height) for staggered arrays were sensitive to building area density, but those for square arrays were not. (2) The relative contributions of ejections to sweeps (S2/S4 at the building height for square arrays were sensitive to building area density and nearly equalled or exceeded 1.0 (ejection dominant), but those for staggered arrays were insensitive to building area density and were mostly below 1.0 (sweep dominant). (3) Streaky patterns of longitudinal low speed regions (i.e., low speed streaks) existed in all flows regardless of array type. Height variations of the buildings in the square array drastically increased the drag coefficient and modified the turbulent flow structures. The mechanism of D-type and K-type urban-like roughness flows and the difference from vegetation flows are discussed. Although urban-like roughness flows exhibited mixed properties of mixing layers and flat-wall boundary layers as far as S2/S4 was concerned, the turbulent organized structures of urban-like roughness flows resembled those of flat-wall boundary layers. © Springer 2006.

DOI： 10.1007/s10546-005-5294-2

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DOI： 10.2151/jmsj.84.187

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DOI： 10.2208/prohe.50.1069

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DOI： 10.2208/prohe.50.463

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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.<BR>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^-2 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/s00704-005-0141-4

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DOI： 10.2151/jmsj.84.187

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DOI： 10.2208/prohe.50.451

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DOI： 10.2208/prohe.50.445

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DOI： 10.2208/prohe.50.493

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Language：English   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   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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Language：English   Publisher：SPRINGER  

We propose a simple theoretical radiation scheme for regular building arrays. The essential difference of the present radiation scheme from the previous ones is the explicit consideration of the three-dimensional features of the surface geometry. The model is assumed to be an infinitely extended regular array of uniform buildings, each building composed of six faces (roof, floor, and four vertical walls). Without using time-consuming iterations or statistical approaches, we calculated the view factors of the faces, the complicated sunlit-shadow distributions, and the resulting canopy albedo for any time and location. The model was evaluated by comparing to outdoor experiments in a wide range of seasons and surface geometries. The simulated canopy albedos agreed well with measured values, and the accuracy is a significant improvement over two-dimensional-based model outputs.

DOI： 10.1007/s10546-004-8662-4

Web of Science

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Language：English  

We propose a simple theoretical radiation scheme for regular building arrays. The essential difference of the present radiation scheme from the previous ones is the explicit consideration of the three-dimensional features of the surface geometry. The model is assumed to be an infinitely extended regular array of uniform buildings, each building composed of six faces (roof, floor, and four vertical walls). Without using time-consuming iterations or statistical approaches, we calculated the view factors of the faces, the complicated sunlit - shadow distributions, and the resulting canopy albedo for any time and location. The model was evaluated by comparing to outdoor experiments in a wide range of seasons and surface geometries. The simulated canopy albedos agreed well with measured values, and the accuracy is a significant improvement over two-dimensional-based model outputs. © Springer 2005.

DOI： 10.1007/s10546-004-8662-4

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Publisher：Japan Society of Civil Engineers  

Heterogeneous surface conditions modify the flow structure of the convective boundary layer (CBL). We investigated this impact focusing on the spatial representativeness of eddy-covariance (EC) point observations. The typical daytime boundary layer was simulated using large eddy simulation (LES), where horizontal heterogeneity was imposed on the ground surface heating as one-dimensional sinusoidal variation. The effect of variation of the wavelength and amplitude on the vertical heat transport was examined.<BR>The surface budged based on the point EC method is examined excluding the net vertical heat transport due to the mesoscale circulations invoked by surface heterogeneity. The mesoscale circulation is represented using a phase average. The result found that our simulated EC point measurements still underestimate this energy budget. However, this deficit gets close to zero when the surface heterogeneity is strong. This underestimate can be strongly attributed to the turbulent organized structure (TOS) developed parallel to the mesoscale circulation.

DOI： 10.2208/prohe.49.343

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DOI： 10.2208/prohe.49.349

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DOI： 10.2208/prohe.49.361

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Language：English   Publisher：KLUWER ACADEMIC PUBL  

The spatial representativeness of heat fluxes on the basis of single-tower measurements, and the mechanism of the so-called energy imbalance problem, are investigated through numerical experiments using large-eddy simulation (LES). LES experiments are done for the daytime atmospheric boundary layer heated over a flat surface, as a best-case scenario completely free of sensor errors and the uncertainties of field conditions. Imbalance is defined as the deviation of the 'turbulent' heat flux at a grid point from the horizontally averaged 'total' heat flux. Both the theoretical and numerical results of the present study suggest the limitation of single-tower measurements and the necessity of horizontally-distributed observation networks.
The temporally averaged 'turbulent' flux based on a point measurement systematically underestimates the 'total' flux (negative imbalance). This is attributed to local advection effects caused by the existence of turbulent organized structures (TOS), whose time scale is much longer than that of thermal plumes. The temporal and spatial change of TOS patterns causes low-frequency trends in the velocity and temperature data resulting in large scatter of the flux estimates. The influences of geostrophic wind speed, averaging time, observation height, computational domain size and resolution on tower-measured fluxes are also discussed. Finally, it is suggested that a weak inhomogenity in surface heating may reduce the negative bias of flux estimates.

DOI： 10.1023/B:BOUN.0000007225.45548.7a

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DOI： 10.1023/B:BOUN.0000027909.40439.7c

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DOI： 10.1175/JAM2153.1

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DOI： 10.2208/prohe.48.163

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DOI： 10.2208/prohe.48.607

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DOI： 10.1175/JAM2153.1

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DOI： 10.2208/prohe.48.139

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This paper aims to develop an environmental evaluation system by integrating traffic simulator and regional atmospheric simulator in order to analyze the effect of transportation policy for wide-area and to estimate traffic flow and atmospheric environment change, particularly focusing on SPM. Traffic characteristics and mol-side-land-use information on the region, traffic signal were inputted in traffic microscopic simulation &ldquo;Paramics&rdquo;. Especially we developed a new model for modifying OD matrix to improve the accuracy of traffic flow, and a PM emission model to calculate PM volume in high-resolute time scale by considering vehicle behavior and geographical characteristics.

DOI： 10.2208/jscej.2004.772_115

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DOI： 10.1023/B:BOUN.0000027909.40439.7c

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DOI： 10.2208/prohe.48.175

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DOI： 10.2208/prohe.48.169

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Publisher：Japan Society of Civil Engineers  

Numerical simulations of canopy albedo for 3 dimensional model cities are performed using the Simple Urban canopy Model for Meso-scale simulation (SUMM). The algorism of the SUMM is described in this study. Model parameters and analytical conditions appropriate for validation studies are examined, and then the simulation results are compared with the experimental data. The model results agree fairly well with experimental results, even though slight disagreements exist especially for low solar angles. Both the simulations and experiments demonstrate that urban geometries significantly influence canopy albedos.

DOI： 10.2208/prohe.47.55

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Language：Japanese   Publisher：環境技術学会  

DOI： 10.5956/jriet.32.178

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Language：Japanese  

DOI： 10.3178/jjshwr.16.477

CiNii Books

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Language：Japanese  

DOI： 10.3178/jjshwr.16.491

CiNii Books

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DOI： 10.5359/jawe.2003.97_13

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DOI： 10.2208/prohe.47.37

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DOI： 10.2208/prohe.47.19

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Publisher：Japan Society of Civil Engineers  

To investigate the dependencies of the profiles on the atmospheric stability (z'/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'/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：English   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

Web of Science

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Language：Japanese  

DOI： 10.3178/jjshwr.15.253

CiNii Books

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DOI： 10.2208/prohe.46.97

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DOI： 10.2208/prohe.46.91

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DOI： 10.2208/prohe.46.85

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Language：Japanese  

DOI： 10.3178/jjshwr.15.243

CiNii Books

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DOI： 10.2208/prohe.46.79

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Language：Japanese  

CiNii Books

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10604566

Language：English   Publisher：SPRINGER  

&apos;Kanpachi Street Cloud (KSC)&apos; is an unusual small-scale cumulus cloud line visible during calm summer conditions over a major street in the Tokyo metropolitan area. In order to understand the mechanism leading to the formation of this cloud line, numerical simulations have been performed using the Regional Atmospheric Modelling System. The general characteristics of the simulated KSC agree well with observations. On a large-scale view, the KSC can be characterized as a cumulus cloud line generated at the convergence line of two sea breezes on the western side of Tokyo Bay, while on the microscale view, it resembles Benard-type thermal convection modified longitudinally by wind shear.
The location of the convergence line leading to the KSC formation coincides with the Kanpachi street location, although the street itself does not make any direct effect on the KSC formation. Additional numerical experiments were performed to identify causes of the KSC formation in accordance with urbanization, by changing anthropogenic heat impact, land-cover and grid resolution. They confirmed that the formation of the KSC requires two meteorological processes at the same time: (1) the convergence of two sea breezes - the local south-eastern sea breeze from Tokyo Bay and an extended southern sea breeze from the Pacific Ocean, respectively; (2) Forcing due to an urban heat island. It is shown that urbanization could change the intensity and position of the KSC through enhancement of local upward motions and changes in the near-surface horizontal pressure gradient between urban and sub-urban areas. Further, fine horizontal grid resolution is needed to be able to resolve these local thermal convection issues.

DOI： 10.1023/A:1026504904902

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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'/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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DOI： 10.2208/prohe.43.91

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DOI： 10.11426/nagare1982.18.101

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DOI： 10.2208/prohe.43.233

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Language：Japanese   Publisher：日本化学会  

CiNii Books

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Language：Japanese  

DOI： 10.2208/jscej.1999.635_1

CiNii Books

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DOI： 10.2208/prohe.42.49

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DOI： 10.2208/prohe.42.43

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

Oikawa model (1985) was improved to simulate annual variations of dry-matter productions of forests. Spatial information such as tree density and canopy closure were included into the model, and the validity of this model were discussed. In terms of qualitative aspects, several kinds of experimental laws of forest growth such as (1) overshooting of leaf biomass during the process of canopy closure, (2) dependence of overshooting periods on tree density, (3) constant final yield, and (4) linear relationship between leaf life-span and leaf biomass, were well simulated. In quantitative view points, simulation results were also compared with the field observation data by Hachiya et al. (1989) for high density stands of Pinus Densiflora. Annual changes of biomass and primary production rate were simulated well, but litterfall rate was not.

DOI： 10.3178/jjshwr.11.472

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Language：Japanese  

DOI： 10.2208/jscej.1998.587_109

CiNii Books

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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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Other Link： https://jlc.jst.go.jp/DN/JALC/00055478977?from=CiNii

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Language：Japanese   Publisher：気象利用研究会  

CiNii Books

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Language：Japanese   Publisher：Japan Association for Wind Engineering  

DOI： 10.5359/jawe.1998.75_49

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00385957784?from=CiNii

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Language：Japanese  

DOI： 10.3178/jjshwr.10.329

CiNii Books

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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 (&rho; c &lambda;) 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 &rho; c &lambda; have a reasonable value. 2) Estimated diurnal variations of G agree very well with that observed. 3) The spatial distribution of &rho; c &lambda; is also estimated from the surface temperature distribution obtained by the thermo-graphy.

DOI： 10.2208/prohe.41.1097

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DOI： 10.2208/prohe.41.43

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DOI： 10.2208/prohe.41.123

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DOI： 10.2208/prohe.40.237

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DOI： 10.2208/prohe.40.243

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Language：Japanese  

DOI： 10.2208/jscej.1996.545_1

CiNii Books

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

Multilayer energy budget model for vegetation canopy is incorporated into a meso-scale meteorological model based on a turbulent closure method. Two types of numerical experiments are performed for investigating the mechanical and radiative effects of vegetation to meso-scale climate, one of which is for one dimensional planetary boundary layer, and another is two dimensional thermally induced wind over a mountain range. Three kinds of canopy model, multilayer model (ML), SIB model and roughness model (RM), are applied to these problems and following results are obtained; 1) In case of dense vegetation, the difference of energy balance between each models are very small. However, SIB and RM overestimate the stability effect on the surface drag, so that the wind velocity is overestimated in day time and under-estimated in night. 2) In case of sparse vegetation, the difference of results between each models are larger than in case of dense vegetation. The main fault of RM is caused by lack of radiative process, and that of SIB is by the turbulence parameterization of lower part of canopy layer.

DOI： 10.3178/jjshwr.8.547

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

Multilayer energy budget model for vegetation canopy is incorporated into a meso-scale meteorological model based on a turbulent closure method. Two types of numerical experiments are performed for investigating the mechanical and radiative effects of vegetation to meso-scale climate, one of which is for one dimensional planetary boundary layer, and another is two dimensional thermally induced wind over a mountain range. Three kinds of canopy model, multilayer model (ML), SIB model and roughness model (RM), are applied to these problems and following results are obtained; 1) In case of dense vegetation, the difference of energy balance between each models are very small. However, SIB and RM overestimate the stability effect on the surface drag, so that the wind velocity is overestimated in day time and under-estimated in night. 2) In case of sparse vegetation, the difference of results between each models are larger than in case of dense vegetation. The main fault of RM is caused by lack of radiative process, and that of SIB is by the turbulence parameterization of lower part of canopy layer.

DOI： 10.3178/jjshwr.8.547

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, an attempt is made to provide a tool for estimating energy balance and thermal load of human body as one of thermal comfort indexes in outdoor environments. This method is applied to four sets of meteorological field observation data. The characteristics of each component of human energy balance are examined in the following view points;<br>1) seasonal effect (summer and winter), 2) effect of ground cover (concrete and vegetation) and 3) effect of clothes.

DOI： 10.2208/jscej.1995.509_35

CiNii Books

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Language：English   Publisher：Kluwer Academic Publishers  

A Large Eddy Simulation (LES) model representing the air flow within and above a plant canopy layer has been completed. Using this model, the organized structures of turbulent flow in the early developmental stages of a crop are simulated and discussed in detail. The effect of the drag due to vegetation is expressed by a term added to the three-dimensional Navier-Stokes equation averaged over the grid scale. For the formulation of sub-grid turbulence processes, the equations for the time-dependent SGS (Sub-Grid-Scale) turbulence energy equation is used, which includes the effects of dissipation (both by viscosity and leaf drag), shear production and diffusion. The organized structure of turbulent flow at the air-plant interface, obtained numerically by the model, yields its contribution to momentum transfer. The three-dimensional large eddy structures, which are composed of spanwise vortices ('rolls') and streamwise vortices ('ribs'), are simulated near the air-plant interface. They are induced by the shear instability at inflection points of the velocity profile. The structure clearly has a life cycle. The instantaneous image of the structure is similar to those observed in the field observations of Gao et al. (1989) and in the laboratory flume experiments of Ikeda and Ota (1992). These organized structures also account for the well known fact that the sweep motion of turbulence dominates momentum transport within and just above a plant canopy, and the motion of ejection prevails in the higher regions. © 1994 Kluwer Academic Publishers.

DOI： 10.1007/BF00705599

Scopus

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Language：English   Publisher：KLUWER ACADEMIC PUBL  

A Large Eddy Simulation (LES) model representing the air flow within and above a plant canopy layer has been completed. Using this model, the organized structures of turbulent flow in the early developmental stages of a crop are simulated and discussed in detail.
The effect of the drag due to vegetation is expressed by a term added to the three-dimensional Navier-Stokes equation averaged over the grid scale. For the formulation of sub-grid turbulence processes, the equations for the time-dependent SGS (Sub-Grid-Scale) turbulence energy equation is used, which includes the effects of dissipation (both by viscosity and leaf drag), shear production and diffusion.
The organized structure of turbulent flow at the air-plant interface, obtained numerically by the model, yields its contribution to momentum transfer. The three-dimensional large eddy structures, which are composed of spanwise vortices ('rolls') and streamwise vortices ('ribs'), are simulated near the air-plant interface. They are induced by the shear instability at inflection points of the velocity profile. The structure clearly has a life cycle. The instantaneous image of the structure is similar to those observed in the field observations of Gao et al. (1989) and in the laboratory flume experiments of Ikeda and Ota (1992). These organized structures also account for the well known fact that the sweep motion of turbulence dominates momentum transport within and just above a plant canopy, and the motion of ejection prevails in the higher regions.

DOI： 10.1007/BF00705599

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DOI： 10.2208/jscej.1993.461_39

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Publisher：Japan Society of Civil Engineers  

Large eddy simulations with meshes fine enough to resolve the roads have been performed to investigate the characteristics of convective boundary layer over Otemachi and the Imperial Palace as an example of urban area. Nondimensional profiles of mean temperature and turbulent intensities agree well with experimental data, and it is shown that the vertical convection and the entrainment are more effective when the ground surface is heated uniformly. It is also shown that many thermals grow up from the asphalt roads while the down stream region are generated around the Imperial Palace.

DOI： 10.2208/prohe.37.177

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DOI： 10.2208/prohe.37.355

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DOI： 10.2208/prohe.36.501

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DOI： 10.2208/prohe.36.535

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DOI： 10.2208/prohe.36.689

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DOI： 10.2208/prohe.36.495

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Language：English   Publisher：ELSEVIER SCIENCE BV  

The boundary-fitted grid method, which transforms a complicated computational domain into a rectangular domain, is applied for the moisture and solute transport problems in the unsaturated soil layer of an S-shaped model hillslope. In the transformed domain, the fundamental equations of moisture and solute transport (i.e. the Richards equation and the Fickian equation) can be easily discretized into the finite-difference form.
For three types of rainfall pattern (a unit rainfall, two-unit successive rainfalls and two unit rainfalls with a lag between them), hydrographs of total (pre-event and event water) and event water discharges, contour lines of soil moisture, pressure and total hydraulic head distributions, and flow velocity vectors are compared. For a relatively thick soil layer or for a relatively light rainfall, the capillary fringe effect plays an important role, whereas for a relatively thin soil layer or for a relatively heavy rainfall, overland flow from a variable source area is superimposed on the capillary-fringe-type runoff.

DOI： 10.1016/0022-1694(91)90189-O

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DOI： 10.2208/prohe.35.585

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DOI： 10.2208/prohe.35.21

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DOI： 10.2208/prohe.35.27

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Publisher：Japan Society of Civil Engineers  

Two sets of lysimeter with wind tunnel were constructed, one of which was grassed (40cm height) and the other of whichwas turf (5cm height). Close relationship between CO₂flux and insolation, humidityflux and vapor pressure difference, heatflux and humidityflux has been observed. Grass shows much effect of moderating the cliaate, but not turf, because of their difference in evapotranspiration rate and shelttering effect.<BR>Numerical simulation using NEO-SPAM (soil-plant-air-model) has been performed to see the effect of the allocation of vegetation. Vegitation is more effective in moderating the climate if the separation of vegetated zone are shorter, and leaf area density is important in terms of both the shelttPring effct and latent heat effect.

DOI： 10.2208/prohe.34.235

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Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

Two sets of lysimeters (soil packed box with artificial rainfall equipment) with wind tunnels have been installed. In one lysimeter, grass was planted, while the other was kept bared. As for air flow, insolation intensity, wind velocity, air flow temperature, humidity and CO₂ concentration were measured. As for soil layer, the water content and soil temperature were recorded.<BR>Considerable changes in temperature, huridity and CO₂ concentration have been observed in the grassed lysimeter, while less changes have been detected in the bared lysimeter, showing the remarkable effect of plant transpiration and photosynthesis for modifying the environment of atmosphere.<BR>A brief description of the numerical simulation of 'soil-plant-air' system is given to confirm the experimental result.

DOI： 10.3178/jjshwr.2.61

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DOI： 10.2208/prohe1975.33.685

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DOI： 10.2208/prohe1975.32.257

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