Analysis Of Heat Island Effect Of Guanzhong Plain Urban Agglomeration Based On WRF-RF Model

The temporal and spatial characteristics and influencing factors of the heat island effect are of great significance to understand and improve urban heat pollution,but the relevant research on the heat island effect of the Guanzhong Plain Urban Agglomeration needs to be strengthened.In this paper,the mesoscale weather forecast model(WRF)is combined with the random forest algorithm(RF)to construct the WRF-RF model and simulate the urban nearsurface temperature,with calculating and analyzing the spatial and temporal characteristics of the heat island effect of the Guanzhong Plain Urban Agglomeration,and then explore the contribution of natural and human factors to the heat island effect based on the geographically weighted regression model.The main conclusions are as follows:(1)WRF-RF model is more accurate in simulating the near-surface air temperature and energy budget of the Guanzhong Plain Urban Agglomeration.Compared with the WRF model,random forest algorithm,and monitoring station interpolation,the WRF-RF model is more efficient and accurate.The spatial correlation coefficient of simulated near-surface(2m)air temperature can reach more than 0.9,and can reflect the effect on air temperature of underlying surface conditions such as terrain.(2)The heat island effect of the Guanzhong Plain Urban Agglomeration has obvious spatial heterogeneity and seasonal variation.Xi’an has the strongest and the largest range of heat island effect.In spring and summer,the range of strong heat island increases obviously in the central areas of big cities such as Xi’an and Xianyang,while the heat island effect weakens gradually in autumn and winter.(3)The heat island effect of the Guanzhong Plain Urban Agglomeration is affected by both natural and human factors,and the natural factors play a leading role.Firstly,the terrain is the main controlling factor of the urban heat island effect.The lower the altitude is,the more obvious the urban heat island effect is.The enhancement of the heat island effect is most the flat area.In terms of seasonal and monthly changes,humidity and solar radiation play a leading role,and the solar radiation is enhanced and humidity is slowed down.The contribution of solar radiation is higher than that of humidity.(4)The heat island effect of Guanzhong Plain Urban Agglomeration was weakened during the COVID-19 epidemic.After the outbreak of COVID-19 at the beginning of 2020,the range of strong heat island in the Guanzhong Plain Urban Agglomeration has been reduced by 31.5%after human activities have been greatly weakened.However,the strong heat island region still appears in the main urban area of the "Xianyang-Xi’an-Weinan-Yuncheng" urban belt from west to east,and the overall situation of the heat island effect has not changed fundamentally.