抄録
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.
