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Hideki Kikumoto, Satoru Iizuka, Masayuki Hara, Yoichi Kawamoto, Akashi Mochida, Ryozo Ooka, Tsubasa Okaze, Yingli Xuan, Urban climate projections in the 2030s/50s for major cities of Japan using downscaling techniques, 10th International Conference on Urban Climate / 14th Symposium on the Urban Environment, 2018.08. |
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Yoichi Kawamoto, Effect of Urbanization on the Urban Heat Island in the Fukuoka-Kitakyushu Metropolitan Area, Japan, 4th International Conference on Countermeasures to Urban Heat Island, 2016.06, 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.. |
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Yoichi Kawamoto, Effect of urbanization on the urban climate in coastal city, Fukuoka-Kitakyushu metropolitan area, Japan, 9th International Conference on Urban Climate, 2015.07. |
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Takamasa Hasama, Yoshiaki Itou, Koji Kondo, Manabu Yamamoto, Tetsuro Tamura, Yoichi Kawamoto, Mitsuo Yokokawa, Large-Eddy Simulation of Wind Pressure Prediction for High-Rise Building on Urban Block, 14th International Conference on Wind Engineering, 2015.06. |
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Yoichi Kawamoto, Fundamental Urban Morphology Analysis for Use in Urban Canopy Model, 7th Japanese-German Meeting on Urban Climatology, 2014.10, 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.. |
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川本 陽一, Doppler lidar observations of wind fields over the Tokyo metropolitan area, 6th Japanese-German Meeting on Urban Climatology, 2012.09, 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.. |
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川本 陽一, Doppler lidar observations of wind fields over the Tokyo metropolitan area, 8th International Conference on Urban Climates, 2012.08, 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.. |
