The Relationship Between Heat Island Effect And Land Cover Type Change In Shenyang

With the improvement of living standard,People’s pursuit of living environment is also getting higher and higher.However,in recent years,with the gradual acceleration of the urbanization process in cities and towns,leading to the gradual destruction of people’s living environment,the high temperature extreme weather occurred in a series of years makes people very worried about the environment.With the introduction of the concept of urban heat island effect,the attention to urban heat island has gradually increased in China,because it is not only closely related to our life,but also has a certain impact on the global atmospheric environment,therefore,this thesis selects Shenyang as the research area,the time span is 2000 to 2020,carries on the correlation analysis to the Shenyang nearly 20 years urban heat island effect,the interaction between urban heat island effect and land cover types is also explored in order to make reasonable suggestions for mitigating urban heat island effect in Shenyang.In this thesis,the remote sensing images from 2000 to 2020 are selected and the land surface temperature is retrieved by using the radiative transfer equation method based on the Landsat satellite data,based on the mean-standard deviation method,the heat island intensity is classified,and the land cover from 2000 to 2020 is classified by the supervised classification method,the land use type map is drawn,the data in the map are analyzed and calculated,the land use matrix is obtained,and the land use change in Shenyang in 20 years is analyzed with reference to the land use matrix.The NDBI,NDVI and NDWI of 20 years were extracted,and the spatial overlay analysis function of Arc Gis was used to overlay the NDBI with the land surface temperature and generate 1000 points randomly,extracting the data to the point and deducting them into the linear regression of land surface temperature with NDBI and NDVI in SPSS,and exploring the correlation between land surface temperature and them,the conclusions are as follows:1)Over time,the maximum surface temperature in Shenyang over the past 20 years has been on an upward trend,but the minimum temperature difference is small enough to prove that the heat island effect in Shenyang is getting worse,as a result of the division of heat island intensity,the area of strong heat island has not only been confined to the central urban areas dominated by Shen-he District,He-ping District,Da-dong District and Huang-gu District,but has gradually spread to Hun-nan and Shen-bei New Area,and there’s still a tendency to expand.Based on the retrieval of land surface temperature from remote sensing data of different seasons in different years,it is found that the Heat Island phenomenon in Shenyang is most obvious in summer,followed by winter,Spring and autumn.2)According to the results of land use classification from 2000 to 2020,the largest area is cultivated land,followed by construction land,and in 20 years,the total area of vegetation(arable land,woodland and grassland)decreased by 15.78%,while the area of construction land increased by 13.68%.According to the land use matrix,cultivated land is the most changed type of land,and 18.75% of it is converted to forest land,and 14.14% to construction land.Based on the normalized difference vegetation index(NDVI),normalized difference building index(NDBI)and normalized difference water index(NDWI),it is found that the vegetation coverage of Shenyang decreases gradually along the periphery of the central urban area,that Shenyang has been fighting to stop urbanization.3)The results show that the normalized difference vegetation index(NDVI)is negatively correlated with the land surface temperature,which means that the higher the NDVI,the lower the land surface temperature,while the NDBI is just the opposite,there is a positive correlation between NDBI and land surface temperature,and the NDBI increases with the increase of NDBI.According to the multi-linear fitting results,we can see that the normalized difference vegetation index(NDVI)is an important factor affecting the land surface temperature,and NDBI(normalized difference vegetation index)caused more than NDVI caused by the cooling effect.