In coastal city, it is thought that the sea breeze has great influence on summer diurnal temperature distribution patterns. Understanding the spatial distribution of sea breeze effects will be helpful for making Urban Environment Climate Maps. Consequently, this study aims at making the maps of sea breeze effect distribution using the observed data and the numerical simulation results in Hiroshima plain. The results are revealed as follows: 1) The effect of sea breeze for mitigating urban warming is relatively larger in coastal area and the effect is smaller in the inland area. 2) The spatial distribution patterns of sea breeze effect for mitigating urban warming being made from the numerical calculation is similar to the one which is made from the observed temperature. 3) The temperatures in the area which are affected by sea breeze are also influenced by surrounding ventilation condition (SVC). On the other, the temperatures in the area which is not affected by sea breeze are not influenced by SVC.

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 Urban planning incorporating mitigation of the urban warming which is due to urban heat island phenomenon and global warming is needed. The mitigations that are thought to be suitable in each place should be selected, because the climatic characteristics are different by places in urban area. Accordingly, Urban Environmental Climate Maps (UECMs) are proposed as a tool for examining the suitable mitigation in each place. For making UECMs, at first, it is necessary to understand the summer temperature distribution patterns and factors of them in urban area. Therefore, this study aims at evaluating the relationship between temperature and the factors comprehensively using observed data in Hiroshima plain. As a result, in the daytime, distance from the coastal line in the direction of sea breeze and the rate of building blocking (RBB) in south-southwest direction have effects on the temperature distribution. In the nighttime, RBB in north-northeast direction and surrounding green area have effects.

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近年、地球温暖化と都市ヒートアイランド現象による都市高温化が進んでおり、特に多くの人が利用する都心部においては、快適な屋外空間を形成するために、熱環境改善策を積極的に取り入れた都市環境デザインが求められる。またこのような取り組みを効果的に進めていくためには、都市内における熱環境改善策導入が優先度の高いエリアの抽出が必要である。そのため、広域の気温分布形成要因の分析から中心市街地周辺の気候的特徴（特に海風効果と河川効果）を把握し、さらに中心市街地の熱環境の詳細な現状把握とその形成要因分析を行った上で、中心市街地における熱環境改善策導入推進エリアを抽出することを目的とした。その結果、都心部の昼間の気温分布は河川距離、周辺緑量、周辺建物密度に影響を受けており、その中でも陸風が止み、かつ海風が十分に発達する前の時間帯で地表面被覆の影響が相対的に強くなる。これらの気温形成要因と猛暑日の定義から熱環境改善策導入推進エリアの抽出し、建物密度を減らしつつ、緑化を推進することが効果的であることを示唆した。

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 In recent years, temperatures in urban area rise because of urban heat islands. Therefore, it is necessary to consider the mitigation of urban warming. For proposing the mitigation measures for proper places, this study aims at producing Urban Environmental Climate Maps (UECMs) of Yokohama, a coastal warming urban area, which has a particular climatic characteristic with a sea breeze coming from two directions. In this study, it performed the analysis by using the data from meso-scale meteorological model (WRF) and the field temperature measurement in 2015 and 2016.
 At first, typical summer fine weather days are extracted. Secondly, classification criteria are made by using data of the wind direction and velocity of the Yokohama Local Meteorological Observatory and AMeDAS Tsujido Observatory during summer days in 2015 and 2016. From the results, authors can classify into three patterns, pattern A, pattern B and pattern C. In this study, the target is Pattern C that is defined as “East wind and southwest wind blow”.
 Next, it estimated the sea breeze front by using data from WRF. By using the wind distribution data from WRF, the target area is classified into “Sea breeze arrival zone” and “Sea breeze non-arrival zone” base on the presence of invasions of sea breeze. And the boundary of the 2 zones seems to be the sea breeze front. In order to compare and select the best criteria, the following three criteria are set. By using Criteria 3, the sea breeze front locations are spatially grasped, and the sea breeze arrival time map are computed.
 Next, authors performed the relevant analysis on the temperature and the factors of temperature distribution. Firstly, a multiple regression analysis is performed in order to understand the factors of temperature distribution in the whole target area. It used average hourly measured temperatures in 2015, for each time, as objective variables and five explanatory variables. The results show that the standardized partial regression coefficient of the sea breeze arrival time is large in the positive direction mainly in daytime and the one of NDVI is large in the negative direction mainly in nighttime. Both explanatory variables are meaningful with significant level 5%.
 Based on the sea breeze arrival time map, the target area can be classified into four zones by the sea breeze front location. The result of analyzing the relationship among measured temperature in 2015 and the NDVI, Ratio of Building Blocking (RBB) for each zone, it is found that the factor of temperature distribution varied according to zone.
 Besides, authors performed the analysis on the factors of temperature distribution inside of Yato. Yato is the topography where flatland get into the hill plateau with the horseshoe shape. In the target area, it is revealed that the factors of the temperature distribution of the inside of Yato are different from the outside.
 Finally, authors made the Urban Environmental Climate Maps (UECMs) in the daytime and nighttime based on the factors of the temperature distribution. Also, authors proposed mitigating measures for each zone.

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