Distribution Of The Thermal Environment Under Extreme Hot Weather In Beijing And Influential Factors

Urban thermal environment is one of the most important topics in urban remote sensing research. Due to global climate change and urbanization, the extreme high-temperature events have occurred frequently in recent years and have greatly impacted people’s daily life and social activities. Therefore, it is very necessary to obtain the land surface temperature and air temperature accurately, and study their spatio-temporal distribution and influencing factor when the extreme high-temperature occurred. The above studies are significant in improving the city thermal environment, slow down the extreme high-temperature occurs and city planning.Nowadays, the researches on city thermal environment are mainly about the city heat island, while the city thermal environment researches when the extreme high-temperature occurred are less involve, and the researches with high level have not formed. On the other hand, the researches on city thermal environment are mostly based on the land surface temperature, but fewer based on the air temperature, and the methods for the spatialization of temperature are mainly using interpolation method because lack of data. Beijing has its own particularity of the topography and the surface condition so that using the interpolation method has some limitations.In view of the above, this paper chose the metropolitan city Beijing as study area, and used the remote sensing quantitative inversion methods and GIS spatial analysis methods as well as the multi-source remote sensing data (HJ-1B, MODIS and TM) to acquisition many parameters which related to the city thermal environment. Besides that, this paper combined the meteorological observation data and the basic geographic information data to simulate the land surface temperature and air temperature, and analyzed the city thermal environment when the extreme high-temperature occurred. Finally, this paper put forward some measures to cope with extreme high-temperature which provided decision support for city planning, summer extreme high-temperature disaster management and so on.The main research contents and the main conclusions were drawn as follows:(1)Based on the historical meteorological data, this paper analyzed the variation trend of daily maximum temperature and number of extreme high-temperature days in recent years. The extreme high-temperature in Beijing had significantly increased in recent years. In order to analysis the spatial distribution pattern and characteristics of extreme high-temperature in recent ten years, this paper selected the extreme high-temperature days in June13,2000and July6,2010which had the similarly meteorological conditions. The land surface temperature was increased significantly during the periods of2000-2010. The increase degree of land surface temperature was different, which the city function expanding zone and city development zone were larger than capital function core zone and ecological conservation development zone.(2)Based on the HJ-1B satellite data, this paper used the single channel algorithm inversion to obtain the land surface temperature in July6,2010when the extreme high-temperature occurred, and selected the same period of MODIS data to verify the accuracy. And then, this paper used the regression analysis method to analyze the correlation between the surface temperature and air temperature. According to the surface condition of Beijing, this paper combined with the land use data to structure the temperature space model, and the results were verified by the actual. Finally, through the spatial statistics method, classification of standard deviation method, profile analysis method and scale analysis method, the extreme high-temperature thermal environment was analyzed.(3) Due to the city thermal environment when the extreme high-temperature occurred, this paper used the method of principal component analysis and combined with the land use data, DEM data and multi-source spatial data to explore the driving mechanism of city thermal environment. And this paper creatively used the Defense Meteorological Satellite System (DMSP) Operational Linescan System (OLS) data to represent the human driving force in order to research on the city thermal environment comprehensive. Consideration of each principal component factors, the first principal component reflected the influence of human activity; the second principal component mainly reflected the influence of ecological environment, and the third principal component reflected the comprehensive information.