Research On Long-term Changes And Influencing Factors Of Land Surface Temperature In Shandong Province Based On MODIS Data

In recent years,the rapid urbanization of our country has made significant changes in the urban spatial layout.Meanwhile,it brings marked impact on the surface morphology,local regional climate and global warming in turn.Our research on the long-term temperature trends and influencing factors of different land types not only give a timely understanding of the spatial distribution characteristic of surface temperature,but also helps to plan the city better,build the ecological environment,and promote sustainable development.In this study,we evaluate the development of land surface temperatures(LSTs)in 16 years(from 2003 to 2019)of the Shandong Province.The Moderate Resolution Imaging Spectrometer(MODIS)onboard NASA's Terra and Aqua spacecraft is used such as MODIS11A2,MODIS 01B products,land classification products(MODIS12Q1)and The vegetation index product(MODIS13A2).In our study we analyze the temperature variations in relation to the spatial distribution and temporal development during 2003-2019;study the correlation between land surface temperature changes and land use types;analysis the factors that influence land surface temperature and make some policies to improce this situration.The results are as follows:1)In terms of time distribution,both the land surface temperature in Shandong Province and the sea surface temperature showed an upward trend from 2003 to 2019.Among them,the temperature in June was the highest,and the temperature difference between day and night was the largest.The average temperatures had been rising in summer during day-and nighttime by 2.71? and 0.91?,respectively and in winter during day-and nighttime by 2.26? and 0.16?.Temperatures of the ocean,measured by MODIS in the center of the Bohai Sea,show a slight increase of only 0.285? for the period under study.According to statistics of the surface temperature for the 12 months of 2020,it is found that the average land surface temperature continues to rise from January to July,and the average land surface temperature from July to December shows a downward trend.For validation purposes,the temperature records of several evenly distributed meteorological ground stations.In terms of spatial distribution,different cities have different LST,the coastal areas have lower temperatures than inland areas,and the southwestern part of Shandong Province has higher temperatures.To go into detail,significant variations in LSTs emerge between landlocked and coastal areas induced by different land use and land cover(LULC)units.2)The average surface temperature of different land use types differs greatly.In the past 16 years,the area of farmland,forest,and water bodies in the study area has decreased,and the area of construction land has increased the most.Built-up areas maintain the highest surface temperature during the day,while the forests maintain the lowest surface temperature.The water body has a high specific heat capacity,so the night temperature is the highest,and the temperature of farmland and forest is lower.Concerning analyses in the spatial domain,the vegetation index NDVI,and the impervious surface area index ISA show the strongest correlation with temperature.This study calculated the normalized vegetation index of Shandong Province from 2003 to 2019.The larger the normalized vegetation index,the lower the surface temperature;the larger the impervious surface index,the higher the surface temperature.3)Urban expansion has a greater impact on surface temperature.The city of Liaocheng sprawled by an additional area of 81 km2 and Heze by an area of 85km2.The coastal cities of Weihai and Qingdao expanded by 86km2 and 237 km2respectively.The mean temperature increase for Liaocheng and Heze was 2.7? and 3.0? and for Weihai and Qingdao,2.8? and 4.0? respectively.Regardless of a considerable increase in temperatures from 2003 to 2019,commonly attributable to changes in atmospheric conditions,we could identify a contribution of 0.14?for this time frame,caused merely by the increase in built-up areas of 16.5%in the entire Shandong Province.4)To find out the primary influencing factors in the temporal domain,methods such as Pearson correlation,stepwise analysis,and optimal subset regression were applied.The correlation coefficients and the significance among different factors of LST reveal that the vegetation space dominates LST control followed by the construction space and landscape configuration and diversity.Research shows that the more vegetation accounts for,the more it breaks the connectivity between the landscapes,the more beneficial it is to alleviate the increase in surface temperature.Analyzing the combined effects of further relevant variables/factors,grouped into vegetation space,waterbodies,construction space,landscape configuration,and socio-economics,the percentage of cropland,the ED of construction area,the LSI of landscape and the GDP indicate considerable influence on the daytime temperature in the temporal domain.Therefore,it is possible to appropriately increase green space,control the area of construction land,and enrich the landscape to alleviate the increase in surface temperature.