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

In the coastal cities, the use of the sea breeze to mitigate the urban heat island phenomenon has attracted attention. To accumulate data for the urban climate in the Fukuoka-Kitakyushu metropolitan area, the fourth largest metropolitan area in Japan and located in coastal area, numerical simulations with a meso-scale meteorological model, the Weather Research and Forecast model (WRF), and upper air observation with Doppler LIDAR were carried out in the summer of 2015, simultaneously. The results of this study suggested that the urbanization process weakened sea breeze penetration.

DOI： 10.1016/j.proeng.2016.10.027

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

For urban climate analysis, mesoscale meteorological models are widely utilized. The urban canopy models are used as sub-models of land surface models in mesoscale meteorological models to represent the effect of urban morphology in terms of kinetic effects and surface energy budgets. Normally, in an urban canopy model, buildings in an analysis mesh are assumed to be uniform. However, in reality, the buildings in any given area are not uniform; they can differ in terms of their heights, areas, and shapes. This raises the question whether the gaps between the morphologies of the presumably uniform modelled buildings and the real non-uniform buildings are significant or not. In this study, the urban morphology in Japanese cities is analyzed by the means of Geographical Information System (GIS). Some urban canopy models represent the variations in buildings’ heights based on normal distribution. However, in this study, building distribution in terms of heights reflects power-law distribution on a macro scale in entire Japan, and on a micro scale with a resolution of about 1 square kilometer.

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

都市化の進んだ東京の夏季日中の大気構造把握を目的として，都心部で東京湾岸から9.5km の東京大学と，その北西12.3km の郊外域との境界部において低層用ラジオゾンデによる境界層観測を行った．その他２地点でも補助的な観測を行った．得られたデータから，連続する３日間の海風の発達経過を調べ，海風気塊の熱構造の変動を追った．熱構造がほぼ定常的な午後の時間帯に，対流混合層が成長する形で前記２地点間を進む海風の加熱率は600Wm-2前後と算定された．この加熱の主要構成要素は地表からの顕熱フラックスと都市人工排熱と考えられ，これらの和が600Wm-2程度となるためには，両者とも従来の観測事例や見積り量に比べ，かなり大きな値であることがうかがわれた．

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

A distinct feature of Wuhan is that almost a quarter of the total area of this city is covered with water, leading to its unique hot and humid climate characteristics in summer. However, according to records, water area in built-up zone of Wuhan has been reduced by 130.5 km² from 1965 to 2008, while the annual average air temperature has been increased by more than 3°C. To investigate the quantitative connection between the water area reduction and air temperature increase, three scenarios were simulated in a summer; to evaluate the impact of water reduction on the local thermal environment in different water areas; and to study the impact of water reduction on the urban heat island (UHI) phenomenon. Meso-scale meteorological models of Weather Research and Forecasting model were applied in this study for quantitative assessment and prediction. With the predictions, this study reveals that the decreased water area could affect air temperature, wind velocity and wind flow direction, energy balance and the UHI intensity. The simulations show that areas with significant wind velocity, wind direction and air temperature differences are distributed among the downwind zones. Moreover, the areas with high UHI intensity are wider and farther from the boundary of urban areas because of the reduction of water areas.

DOI： 10.1177/1420326X14546774

Language：English  

Currently, about 50% of the world’s population is living in urban areas, and that figure is predicted to continue to increase (United Nations, Department of Economic and Social Affairs Population Division, Population Estimates and Projections Section (2009) World urbanization prospects: the 2009 revision). On the other hand, many cities are facing problems caused by urbanization. The urban heat island phenomenon, one of the urban climate problems, is a typical environmental problem encountered in dense urban areas in summer. The use of the sea breeze to mitigate the urban heat island phenomenon has attracted attention in coastal cities. Some statistics show that about 40% of the world’s population lives within 100 km of the coast (World Resources Institute, Fisheries (2007) Population within 100 km of coast). Further investigation of the environment in the urban area near the coast is, therefore, important. In this chapter, Tokyo is targeted for investigation. Tokyo is the Japanese capital, and its surrounding region, the Tokyo metropolitan area, comprises a circular area with a radius of 50 km and a population of over 30 million. Within this area, the sea breeze from Tokyo Bay is an important factor mitigating the air temperature rise in summer. However, ongoing urbanization could be changing not only the mechanism of the energy balance on the urban surface but also the sea breeze system in the region. To clarify the effects of urbanization, a mesoscale meteorological model was adopted for analysis. Simulation results suggest that expansion of the Tokyo metropolitan area from the 1970s to the 1990s has induced a temperature rise near the ground and that the difference is largest in inland areas. Moreover, the time of sea breeze penetration is delayed in suburban areas. These results suggest that the ongoing urbanization process could raise the air temperature and change the sea breeze system in the Tokyo metropolitan area.

DOI： 10.1007/978-94-007-2771-7_2

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

Urban land surface schemes have been developed to model the distinct features of the urban surface and the associated energy exchange processes. These models have been developed for a range of purposes and make different assumptions related to the inclusion and representation of the relevant processes. Here, the first results of Phase 2 from an international comparison project to evaluate 32 urban land surface schemes are presented. This is the first large-scale systematic evaluation of these models. In four stages, participants were given increasingly detailed information about an urban site for which urban fluxes were directly observed. At each stage, each group returned their models' calculated surface energy balance fluxes. Wide variations are evident in the performance of the models for individual fluxes. No individual model performs best for all fluxes. Providing additional information about the surface generally results in better performance. However, there is clear evidence that poor choice of parameter values can cause a large drop in performance for models that otherwise perform well. As many models do not perform well across all fluxes, there is need for caution in their application, and users should be aware of the implications for applications and decision making.

DOI： 10.1002/joc.2227

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

We investigated the influence of meteorological factors that affect ozone in summer using both measurement analysis and numerical simulation. The results show that there is a close relationship between changes in meteorological conditions and variations in ozone concentrations over the central Kanto area. In summer, up to 84% of long-term variations in peak ozone concentrations may be accounted for by changes in the seasonally averaged daily maximum temperatures and seasonally averaged wind speeds. The ozone episodes in the Kanto region are dominated by three major patterns, of which Patterns I and II are regular summertime pressure patterns with a 26% and 16% frequency of occurrence, respectively. A detailed process analysis of ozone formation under urban heat island (UHI) at two areas in the Kanto region - urban and rural area - indicates that ozone formation is mainly controlled by chemistry, dry deposition, vertical transport, and horizontal transport processes. The groundlevel ozone concentrations are enhanced mainly by the vertical mixing of ozone-rich air from aloft, whereas dry deposition process mainly depletes ozone. Horizontal transport and chemistry processes play opposite roles in the net change of ozone concentration between the two areas. The results of numerical simulations also indicate that the sea breeze has significant effects on the ozone accumulation and distribution in the Kanto area. The high ozone was first observed in urban area and then was transported to the rural area by sea breeze. At rural area, the highest ozone concentrations were found in late afternoon, about two hours later in comparison with the urban area.

DOI： 10.1016/j.proenv.2011.03.017

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

The summer climate around the Tokyo metropolitan area has been analysed on an urban scale, and the regional characteristics of the thermal energy balance of a bayside business district in the centre of Tokyo (Otemachi) have been compared with an inland residential district (Nerima), using a mesoscale meteorological model incorporating an urban canopy model. From the results of the analysis, the mechanism of diurnal change in air temperature and absolute humidity in these areas is quantitatively demonstrated, with a focus on the thermal energy balance. Moreover, effective countermeasures against urban heat-islands are considered from the viewpoint of each region's thermal energy balance characteristics. In addition to thermal energy outflux by turbulent diffusion, advection by sea-breezes from Tokyo Bay discharges sensible heat in Otemachi. This mitigates temperature increases during the day. On the other hand, because all sea-breezes must first cross the centre of Tokyo, it has less of a cooling effect in Nerima. As a result, the air temperature during the day in Nerima is higher than that in Otemachi.

DOI： 10.1007/s10546-010-9550-8

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

We have assessed the contributions of individual physical and chemical atmospheric processes on ozone formation under different weather conditions during a typical summer month (August 2005) using the MM5/CMAQ modelling system. We found that the ozone episodes in the Kanto region are dominated by three major patterns, of which Patterns I and II are regular summertime pressure patterns with a 26% and 16% frequency of occurrence, respectively. A process analysis at two typical sites in the Kanto region - one located in the central region of Tokyo and the other located in the rural areas of Kanto - indicates that ozone formation is mainly controlled by advection, vertical diffusion, dry deposition, and chemical processes. The ground-level ozone concentrations are enhanced mainly by the vertical mixing of ozone-rich air from aloft, whereas the dry deposition and chemical processes mainly deplete ozone. By investigating the effects of each process under different weather conditions, we found that the significant decrease in ozone removal due to the chemical and advection processes under conditions of high stagnation is the most important cause of the enhanced levels of ozone in the central region of Tokyo. The results of this study can contribute to a better understanding of ozone formation in the Kanto region, and they may be valuable for local policy makers for further development planning.

DOI： 10.1016/j.atmosenv.2010.07.038

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

A large number of urban surface energy balance models now exist with different assumptions about the important features of the surface and exchange processes that need to be incorporated. To date, no comparison of these models has been conducted; in contrast, models for natural surfaces have been compared extensively as part of the Project for Intercomparison of Land-surface Parameterization Schemes. Here, the methods and first results from an extensive international comparison of 33 models are presented. The aim of the comparison overall is to understand the complexity required to model energy and water exchanges in urban areas. The degree of complexity included in the models is outlined and impacts on model performance are discussed. During the comparison there have been significant developments in the models with resulting improvements in performance (root-mean-square error falling by up to two-thirds). Evaluation is based on a dataset containing net all-wave radiation, sensible heat, and latent heat flux observations for an industrial area in Vancouver, British Columbia, Canada. The aim of the comparison is twofold: to identify those modeling approaches that minimize the errors in the simulated fluxes of the urban energy balance and to determine the degree of model complexity required for accurate simulations. There is evidence that some classes of models perform better for individual fluxes but no model performs best or worst for all fluxes. In general, the simpler models perform as well as the more complex models based on all statistical measures. Generally the schemes have best overall capability to model net all-wave radiation and least capability to model latent heat flux.

DOI： 10.1175/2010JAMC2354.1

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

Urban heat island phenomena have been analyzed by numerous researchers using mesoscale meteorological models. Although there are many mesoscale models, MM5 is considered one of the major mesoscale models. In such analysis, a one-dimensional heat balancemodel is primarily used for surface boundary conditions. However, it is necessary to include the effect of the building canopy to analyze the thermal environment at pedestrian level. Therefore, MM5 is incorporated with the urban canopy model. The urban thermal environment in Kanto region is analyzed by means of the new method. The results show better agreement with observation data.

DOI： 10.3130/aije.74.1009

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

Meso-scale climate analysis is very useful to understand the structure of the urban heat island. MM5, provided by National Center for Atmospheric Research, is one of major meso-scale model in the world. However, parameterization of ground surface in MM5 is rather coarse to analyze urban climate. That is, in MM5, ground surface parameters are determined by most superior land-use in each mesh. However, this method is unable to represent detail urban structure, to say, the effect of Cool Island with green or water body is neglected. In this paper, ground surface parameterization in MM5 is modified to represent land-use fraction. Furthermore, effect of anthropogenic heat release is also incorporated in MM5.

DOI： 10.3130/aije.73.1125

Language：English   Publishing type：Research paper (other academic)  

Asian mega cities have continued to expand, and accordingly, various problems, e.g. social, economical and environmental problems, have been widely recognized in Asia. Especially, environmental issues caused by Asian mega cities will affect not only the areas within mega cities but also the whole area of Asian countries because the effects will be widely propagated by atmospheric or marine transportation. Authors have conducted researches related to comprehensive assessment indices for urban sustainability, named as Environmental Indices for Urban Sustainability (EIUS). In the framework of EIUS, both the environmental quality and the environmental load are focused on. An urban sustainability will be evaluated based on the scores for all categories of EIUS [1]. Most of the environmental data used in EIUS are collected from statistical data and those are restricted to point-based data. If area-based data such as vegetation distribution or urban area distribution are required, remotely sensed technique is quite useful. Remote sensing data also has an advantage to compare the parameters of different cities by the same criteria. In the present research, the applicability of remote sensing data to extract area-based environmental data for EIUS was examined. Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) images, observed in 1990s and 2000s, were used to extract vegetation index, albedo and land surface temperature. Urban areas of Bangkok in 1990s and 2000s were extracted from such parameters. Based on the acquired results, the methodology will be improved and applied to extract urban areas in other Asian mega cities.

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東北大学   Country：Japan  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Shepard Hall, City College of New York, New York, USA   Country：Japan  

Event date： 2017.8 - 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島工業大学   Country：Japan  

Event date： 2016.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡大学   Country：Japan  

過密な都市で発生するヒートアイランド現象等の都市気候の諸問題に対し、海風がその緩和策として期待される。日本の首都である東京では大気汚染物質の輸送に着目した上空の流れ場のゾンデ観測が1980年代に行われ（Yoshikado and Kondo文1））、それ以降も海風の観測や数値解析が行われてきた。一方、日本第4の規模である北九州・福岡大都市圏では、海風の観測事例は限られており（例えば、ドップラーソーダを用いた福田他文2）、更なるデータの収集が求められる。
本報では、夏期を対象としてドップラーライダを用いた福岡上空の流れ場の観測を行った結果を報告する。併せて、数値解析による海風の再現実験について報告する。

Event date： 2016.5 - 2016.6

Language：English   Presentation type：Oral presentation (general)  

Venue：National University of Singapore   Country：Singapore  

Because Japan is a mountainous island nation, most of the large cities in Japan are located in coastal areas. In these coastal cities, the use of the sea breeze to mitigate the urban heat island phenomenon has attracted attention. Compared with the Tokyo metropolitan area, the capital of Japan and the largest metropolitan area in the world, the number of urban climate studies in the Fukuoka-Kitakyushu metropolitan area, the fourth largest metropolitan area, is limited. Therefore, to accumulate data for the urban climate in this area, numerical simulations with a meso-scale meteorological model, the Weather Research and Forecast model (WRF), and upper air observation with Doppler LIDAR were carried out in the summer of 2015, simultaneously. To represent the progress urbanization over about three decades, the National Land Numerical Information (NLNI) land-use fractions dataset for Japan in 1976 and 2009 were utilized.
For simulation results of the surface air temperature, the results with NLNI land-use dataset of 2009 showed less errors compared to the observations by Japan Meteorological Agency (JMA) than did the results with the U.S. Geological Survey (USGS) land-use dataset used as the default in the WRF. This comparison suggested that the USGS land-use dataset was unable to represent the urban area precisely.
To consider the effect of the urbanization process over three decades on urban climate in the targeted area, the NLNI land-use dataset of 1976 and 2009 were utilized in the WRF simulations with the mosaic land surface model. From a viewpoint of the surface air temperature, most of the northern part of the Kyushu region became warmer because of urbanization. The urbanization process in the Fukuoka-Kitakyushu metropolitan area also had a possible effect on the sea breeze penetration from Hakata Bay to Fukuoka city. Comparing the two simulation results with NLNI land-use datasets and the Doppler LIDAR observations, the simulation results with NLNI of 1976 showed faster sea breeze penetration and higher wind velocity compared with the observations results and simulation results with NLNI of 2009. The results of this comparison suggested that the urbanization process weakened sea breeze penetration.

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東海大学   Country：Japan  

Event date： 2015.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Toulouse   Country：France  

Event date： 2015.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Porto Alegre   Country：Brazil  

Event date： 2014.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：タワーホール船堀   Country：Japan  

This study investigated the influence of actual urban block area for the wind pressure prediction of target high-rise building using large-eddy simulations (LES), and introduced the utilization of High-Performance Computer (HPC) for
LES. Firstly, four LES cases were carried out using 3072 parallel calculation and compared with four wind tunnel experiments, respectively; (1) No-urban block and no-target building case (completely no-obstacle case), (2) No-urban
block and target building case, (3) Urban block and no-target building case, and (4) Urban block and target building case. Both no target-building case (no-urban block and urban block) showed that the same recovery characteristics of vertical velocity profile with the wind tunnel experiment. Both target-building case (no-urban block and target building) showed good correspondence with the wind tunnel experiment for the pressure coefficients of average, standard deviation, max-peak and minimum-peak. Furthermore, LES for target building with complex surface shape on high-rise urban block was carried out using 6144 parallel calculation on “K” computer. In this case, balcony on the building was resolved, and small vortex shedding caused by the balcony was simulated.

Event date： 2014.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京大学   Country：Japan  

計算機の発達に伴い高精度だが大規模な計算資源を要求する数値流体力学手法であるLarge-Eddy Simulation (LES) を利用した建築物の構造骨組用風荷重評価が可能となりつつある。本研究では、大規模並列計算機を使用し実在街区中に位置する高層建築物を対象としたLESにより風圧予測を行った。なお、本研究は九州大学情報基盤研究開発センター公募課題「平成25年度先端的計算科学研究プロジェクト」として、鹿島建設技術研究所と共同研究を行った成果である。

Event date： 2014.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Leibniz Universität Hannover   Country：Germany  

For urban climate analysis, mesoscale meteorological models are widely utilized. The urban canopy models are sub-models of land surface models in mesoscale meteorological models to represent the effect of urban morphology in terms of kinetic effects and surface energy budgets. Normally in the urban canopy model, buildings in one analysis mesh are estimated uniform. However the modeled buildings are uniform, of course the real buildings in any given area are not uniform in building height, building area and building shape. The question is, the gaps between modeled uniform buildings’ morphology and real non-uniform buildings’ morphology are serious or not. In this study, the urban morphology in Japanese cities is analyzed by means of GIS (Geographical Information System). Some urban canopy model represents the buildings’ heights variation based on normal distribution. However in this study, whole buildings’ heights distribution shows power-law distribution on a macro scale in whole of Japan and on a micro scale with resolution of about 1 square kilometer. These analysis result also will be use to update non-uniform urban canopy model in the future work.

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神戸大学   Country：Japan  

メソスケール気象モデルの地表面モデルに都市の影響を反映させる都市キャノピーモデルでは、都市形態を均一と見做してモデル化するのが一般的である。しかし、実在の都市は均一な街区とは言い得ない。そこでGeographical Information Model (GIS) を用いて日本全国の建物形状の解析を行った。解析により、日本国内の全建物の高さは冪分布を示すこと、また1km2程度のグリッドに分割した解析においても同様に冪分布を示すことが明らかとなった。

Event date： 2013.8 - 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北海道大学   Country：Japan  

日本の大都市の多くは沿岸部に位置しており、その様な立地条件では沿岸より吹き込む海風が都市気候の形成に大きく寄与する。沿岸都市における夏期の海風の性状について、東京首都圏を対象として筆者らはこれまで数値解析と観測の両面から取り組んできた。本研究ではGPSゾンデを用いた上空の気象観測と、併せて地上での気象観測を行った。観測結果より海風進入前後の上空の大気環境の変化を明らかにした。

Event date： 2012.9

Language：English   Presentation type：Oral presentation (general)  

Venue：広島工業大学   Country：Japan  

Currently, about 50% of the world’s population is living in urban areas, and that figure is predicted to continue to increase. On the other hand, many cities are facing problems caused by urbanization. The urban heat island phenomenon is a typical environmental problem encountered in dense urban areas in summer. The use of the sea breeze to mitigate the urban heat island phenomenon has attracted attention in coastal cities. In this study, Tokyo is targeted for investigation. Tokyo is the Japanese capital, and its surrounding region, the Tokyo metropolitan area, comprises a circular area with a radius of 50 km and a population of over 30 million. Within this area, the sea breeze from Tokyo Bay is an important factor mitigating the air temperature rise in summer. Yoshikado and Kondo (1989) had carried out large-scale upper air observations using balloons to clarify the transportation of atmospheric pollutants affected by the sea breeze from Tokyo Bay in 1980’s. After that, such kinds of observations focusing on the sea breeze penetration from Tokyo Bay were limited. To clarify the transition of the wind field over the Tokyo metropolitan area, Doppler lidar observations were adopted. One instrument was set at approximately 10 km from coastline of Tokyo Bay, and the other was set at approximately 30 km from coastline. These set of Doppler lidar observations captured sea breeze penetration from Tokyo Bay well.

Event date： 2012.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋大学   Country：Japan  

本研究では、海風の性状把握と都市型短時間強雨の関連性の解明の基礎的検討として、東京湾湾岸に近い東京都内と、東京湾より進入する海風の風下側となる内陸部の埼玉県内の2地点に於いてドップラーライダを用いて上空風の同時観測を行った。

Event date： 2012.8

Language：English   Presentation type：Oral presentation (general)  

Venue：University College Dublin   Country：Ireland  

Currently, about 50% of the world’s population is living in urban areas, and that figure is predicted to continue to increase. On the other hand, many cities are facing problems caused by urbanization. The urban heat island phenomenon is a typical environmental problem encountered in dense urban areas in summer. The use of the sea breeze to mitigate the urban heat island phenomenon has attracted attention in coastal cities. In this study, Tokyo is targeted for investigation. Tokyo is the Japanese capital, and its surrounding region, the Tokyo metropolitan area, comprises a circular area with a radius of 50 km and a population of over 30 million. Within this area, the sea breeze from Tokyo Bay is an important factor mitigating the air temperature rise in summer. Yoshikado and Kondo had carried out large-scale upper air observations using balloons to clarify the transportation of atmospheric pollutants affected by the sea breeze from Tokyo Bay in 1980’s. After that, such kinds of observations focusing on the sea breeze penetration from Tokyo Bay were limited. To clarify the transition of the wind field over the Tokyo metropolitan area, Doppler lidar observations were adopted. One instrument was set at approximately 12 km from coastline of Tokyo Bay, and the other was set at approximately 34 km from coastline. These set of Doppler lidar observations captured sea breeze penetration from Tokyo Bay well.

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：1

Number of peer-reviewed articles in Japanese journals：1

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：2

Number of peer-reviewed articles in Japanese journals：0

Proceedings of International Conference Number of peer-reviewed papers：0

Proceedings of domestic conference Number of peer-reviewed papers：0

Type：Competition, symposium, etc. 

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：4

Number of peer-reviewed articles in Japanese journals：1

Proceedings of domestic conference Number of peer-reviewed papers：1

Type：Competition, symposium, etc. 

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Number of peer-reviewed articles in Japanese journals：2

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc.