Urban Heat Island Effect And Thermal Abnormality Analysis

Urban Heat Island(UHI)is one of the most prominent features of urban development in urban areas where temperatures are higher than those in the suburbs.Based on the MODIS surface temperature product data,this paper extracts spatial patterns of urban thermal grades in Shijiazhuang City in different phases.Statistics of different thermal grade landscape indices are calculated from three aspects: quantitative characteristics,morphological characteristics and structural characteristics.The characteristics of temporal and spatial patterns are analyzed,and different thermal levels are calculated.Transfer the matrix to reveal its temporal and spatial variation.Based on Landsat8 data inversion of surface temperature,the analysis of the driving mechanism of different types of land cover on the formation of urban thermal environment,and the identification of urban land use thermal anomaly identification technology are provided to scientifically formulate and adjust urban planning and development strategies and improve urban thermal environment.Effective theoretical basis.The main conclusions of the study are as follows:(1)In terms of spatial distribution,Shijiazhuang urban heat island has been strengthened from 2001 to 2015.In terms of changes in time,the heat island intensity changes day and night and the seasons change significantly.In the daytime,it is generally characterized by strong summers and weak winters.At night,it shows the opposite law of change with the daytime.(2)In terms of quantity,the intermediate temperature zone and the second-highest temperature zone dominate the urban thermal environment in Shijiazhuang,the area of the intermediate temperature zone and the sub-high temperature zone has increased significantly,and the surface temperature has shown a rising trend.In terms of morphology,the shape of the thermal zone during the daytime is better than that of the nighttime.For the sake of complexity,landscape shapes of each thermal level tend to be more regular,and the shape is simpler.In terms of structure,the degree of polymerization of landscape patches of each thermal level increases as a whole,showing good polymerization,and the night-time polymerization is weaker than that during the day.(3)The surface temperature of Shijiazhuang City showed an increasing trend,which was mainly reflected in the transition from the sub-low temperature zone to the medium temperaturezone and the intermediate temperature zone to the sub-high temperature zone,in which the nighttime was more stable than the daytime increase.The surface temperature will hardly turn violently,basically increasing or decreasing step by step.(4)Cultivated land,forest land and water area have played a cooling effect on the thermal environment of Shijiazhuang.Grassland,artificial surface and bare soil have exerted a warming temperature effect on the thermal environment of Shijiazhuang.The contribution index of the artificial surface is 0.4,the artificial surface contributes most to the formation of Shijiazhuang heat island.The index of the contribution rate of cultivated land is-0.35,cultivated land is the type of land cover that contributes most to the heat island effect of Shijiazhuang.(5)This study proposes the technology of urban site object thermal anomaly recognition,uses the improved RST algorithm to establish a temperature background library,uses the "k?" criterion as the principle of thermal anomaly to establish a threshold to extract thermal anomaly objects,and the accuracy is verified to be 87.6%.