Study On Characteristics Of Urban Heat Island Effect In Jinan City Based On Remote Sensing Technology

With the advancement of urbanization,the spatio-temporal evolution of urban heat island has gradually become a research hotspot.Based on the Landsat series of remote sensing satellite data,the remote sensing data of Jinan City in Octobers 1990,2009 and 2017 was selected to invert the surface temperature in each period with the radiative transfer equation method.Combined with the urban planning data and urban road data,and the data on types of land use extracted in different periods,the spatio-temporal evolution characteristics and influencing factors of urban heat island in Jinan were studied,providing references for the study on construction of an“environment-friendly metropolitan area of ecological habitability”in Jinan.1.The inversion data of the surface temperature of Jinan indicated that in 1990,the average surface temperature of Jinan in 1990,2009 and 2017 showed a growing trend,18.5?,27.04?,and 28.36?,respectively.Since 1990,it can be clearly seen that obvious urban heat island effect has been hovering in Jinan City in spatial distribution,and the central heat island(core heat area)has a coverage area of the south Tianqiao District,the east Huaiyin District,and the north Central District and the most parts of the Lixia District.2.In order to identify the influencing scope of urban heat island in Jinan,so as to further analyze the urban thermal environment,the urban heat island intensity of Jinan City was classified and extracted.Based on the hierarchical differences of surface temperature with standard deviation classification method,heat island intensity was divided into seven ranges:strong heat island effect area,middle heat island effect area,weak heat island effect area,obvious effect-free area,weak cold island effect area,middle cold island effect area,and strong cold island effect area.According to the corresponding pixel,the area statistics of each classified heat island intensity were obtained:From 1990 to 2017,the ratio of area(including strong heat island area,middle heat island area,weak heat island area)affected by urban heat island effect to the total area of Jinan City increased from 31.98%in 1990 to 37.36%in 2017.The urban heat island area increased from 2556.39km~2 in 1990 to 2984.96km~2 in 2017.The prominent feature of the spatial distribution of urban heat island in the central part of Jinan is that the main urban area serves as a strong heat island radiation source,linking the sub-heat island centers—Zhangqiu District in the east and Changqing District in the southwest,respectively,along the main urban road.Since 2009,the distribution of high-temperature urban thermal fields in Jinan has gradually evolved from the“point-chain”type to the“chain-face”structure.3.The research on the urban low-temperature cold island area in Jinan has drawn the following conclusions:The urban low-temperature cold island area in Jinan can be generally divided into three parts:the southern mountain belt,the central Yellow River cold island belt,and the northern plain belt.Most of these areas are covered by water and vegetation,obviously indicating types of land use.The southern mountain belt has the widest low-temperature cold island area,and the low-temperature cold island covering area formed by the Yellow River Basin has shaped the buffer zone of the natural urban heat island in Jinan.The cold island area of Jinan City has a sharply weakening effect on the strong heat island effect of urban built-up areas.4.Combined with the overall urban planning(2011-2022)and the urban economic indicators data of Jinan,the following conclusions are drawn:On the macro level,the spatio-temporal evolution trend of the urban heat island area of Jinan is in line with its urbanization development trend.The expanding scale and speed of the heat island area in Jinan is undoubtedly affected by its regional policies.5.The relationship between surface temperature and vegetation coverage in Jinan city was quantitatively analyzed by using three mathematical models:power,linearity and index.It is concluded that the linear function model can better explain the correlation between vegetation coverage and surface temperature in Jinan.6.In this paper,the land use data of three periods in jinan city were extracted and analyzed with the method of supervision classification.The area of various land use types in jinan city changed a lot,among which the urban building land and rural building land increased the most,569.865km~2 and 127.326km~2 respectively compared with 1990.The urban construction land expanded by 1.46 times compared with1990.Combined with the above research,it can be seen that the regional scope of jinan city affected by the urban heat island effect will increase,and the urban heat island effect will become increasingly serious.The urban thermal environment of jinan is not optimistic.