Analysis On Temporal And Spatial Variation Of Comfort Index Of Human Body Of Summer In Yangtze River Delta Urban Agglomeration And Its Influencing Factors During 1981-2015

With the rapid development of society and economy,the significant improvement of living standards and the in-depth implementation of the "people-oriented" concept,people are increasingly demanding for the comfort of living environments,so the research on human comfort has received more and more attention.Combining daily meteorological data and ERA-Interim reanalysis data,this study uses GIS technology to mesh meteorological elements and calculate the comfort index of human body through the CIHB empirical formula,then analyze the spatial-temporal variation of summer CIHB in the Yangtze River Delta urban agglomeration during 1981-2015.This study also analyzes its influencing factors by combining topographic data,land surface temperature data,vegetation index data,land cover type data and statistical yearbook data.The results are as follows:(1)The 35-year average summer CIHB in the Yangtze River Delta urban agglomeration has obvious spatial and temporal distribution characteristics.The CIHB gradually increases from northeast to southwest and the annual growth trend shows the characteristic of high in the east and low in the west.The characteristic of human comfort is mainly warm.The comfort zone is mainly concentrated in the northeast coastal areas and the mountainous regions.(2)The 35-year average summer CIHB in the Yangtze River Delta urban agglomeration is different from it of the whole country.The annual and 35-year average summer CIHB in the Yangtze River Delta urban agglomeration are both higher than that of the whole country;The CIHB in the Yangtze River Delta urban agglomeration gradually increases from northeast to southwest,with a certain relationship with the terrain.The national CIHB,except for the Qinghai-Tibet Plateau,gradually decreases from south to north,with a significantly negative correlation with terrain;The change of CIHB in the Yangtze River Delta urban agglomeration is as significant as it of the whole country.The spatial distribution characteristic of the rate in the Yangtze River Delta urban agglomeration is basically high in the east and low in the west,but the national characteristic is basically high in the north and low in the south;The changesof the CIHB in the Yangtze River Delta urban agglomeration and the whole country are both phased but the phases are different.(3)There are significant differences in the spatial-temporal distribution and changes of meteorological elements such as the average summer temperature,high temperature days,relative humidity and wind speed in the Yangtze River Delta urban agglomeration.Mountain temperature is low and the overall trend is rising,with the rate high in the east and low in the west;The regions with multiple high-temperature days are mainly concentrated in the central and mountain basin and hills of Zhejiang Province.The overall trend is growth and the areas with significant growth are mainly concentrated in non-highland areas of Zhejiang Province;The relative humidity gradually decreases from the eastern coast to the western inland.The overall trend is decreasing and the decline of central region is more significant;The wind speed gradually decreases from the east coast to the west inland.The overall trend is decreasing and the decline is more significant in the east.(4)There are significant differences in the spatial-temporal distribution and changes of surface factors such as the average summer land surface temperature,vegetation index and land cover types in the Yangtze River Delta urban agglomeration.High land surface temperature is mainly concentrated in fast-growing areas.The trend is mainly rising,but the characteristic in various regions is complicated.The areas with significant increase are mainly concentrated in the eastern region;NDVI shows the characteristic of high in the southwest and low in the northeast.The areas with high NDVI are mainly concentrated in mountainous areas.The NDVI generally shows an upward trend and the annual rate of change is high in the southwest and low in the northeast;Land cover types also have changed.Wetlands and agricultural land have decreased while urban buildings,vegetation and water have increased.(5)The correlations between the main influencing factors and summer CIHB in the Yangtze River Delta urban agglomeration are significantly different.There is a significant positive correlation between air temperature,high temperature day,land surface temperature,urban buildings and CIHB;There is a negative correlation between relative humidity,wetlands,water,agricultural land,vegetation and CIHB;The correlation between wind speedand CIHB is weak.Generally speaking,the impact of wind speed is complex and not significant.The correlation between altitude and summer CIHB basically shows an inverted "U" shape.For low-altitude areas below 100 m,the altitude are positively correlated with summer CIHB,and for areas above 100 m,the altitude are negatively correlation with summer CIHB;The NDVI and CIHB have been growing for a long time,so their correlation is mainly positive in the long time series.However,the NDVI and CIHB show a negative correlation in different spaces at the same time;In the time series,population has a positive correlation with summer CIHB.However,the correlation in spatial distribution is relatively complicated.