Research On The Effects Of Land Cover Change On Land Surface Energy Balance And Its Climatic Effects In The Huanghuaihai Region

Land cover change is considered to be one of the main driving forces of the transformation of surface energy balance,which has an impact on the regional climate through different degrees of biogeochemical and physical processes.Therefore,the purpose of this study is to analyze the surface energy budget caused by various surface energy factors under different land cover types,mainly using the surface energy balance algorithm,the combination of Theil-Sen slope estimation and Mann-Kendall,and mutation detection.Based on the differences of land cover data from 2000 to 2020,this paper deeply discusses the evolution mechanism of land cover change,the spatio-temporal change of local climate and the impact of land cover change on surface energy budget.The surface energy balance mechanism and climate effect of land cover change in Huang-Huai-Hai area from 2000 to 2020 are discussed,and the corresponding land management measures are given.It is expected to provide theoretical support for regional ecological environment protection,land cover spatial optimization adjustment and sustainable development.The main conclusions of this study are as follows:(1)From 2000 to 2020,among the six types of land cover,the conversion area of cropland is the largest,and the transfer area of construction land is the largest,of which 93.44% of the cropland is converted to construction land.It shows that in the process of urbanization,a large number of cropland loss is mainly converted to construction land.The analysis of different land cover types shows that the trend of latent heat flux was: natural and semi-natural land > converted to natural and semi-natural land > converted to cropland >cropland > construction land > converted to construction land.The latent heat flux of construction land and converted to construction land greatly affected by human activities is always lower than that of other land cover types.According to the analysis of net radiation,it is found that the net radiation value of natural and semi-natural area is much higher than that of construction land and converted to construction land,and the net radiation value of construction land and converted to construction land decreases most rapidly.(2)Under the influence of different intensity of human activities and natural toughness,the energy budget of different land cover types is significantly different.The net radiation(NR)value is the highest in the natural and semi-natural land and converted to the natural and semi-natural land,that is,the natural seminatural area will increase the surface energy intake accordingly.The latent heat flux(LH)has the fastest rising trend in the natural and semi-natural land,and its latent heat flux is much higher than that in the construction land,that is,the natural and semi-natural land plays a key role in surface energy consumption.The surface energy(LH-NR)of different land cover types showed an upward trend,in which the rising trend of construction land and converted to construction land was higher than that of other land cover types.Among them,it is obvious that the increase of construction land has the greatest impact on the surface energy budget,and the expansion of the area of construction land directly affects the negative growth of LH-NR value by15.99%.The trend of LH-NR of different land cover types increases with the increase of the intensity of human activities,indicating that human activities have a tendency to enhance surface energy absorption.(3)The surface temperature trends of the six land cover types were: converted to construction land >construction land > cropland > converted to cropland > natural and semi-natural land > converted to natural and semi-natural land.Cropland increased by 1.16% in 21 years,precipitation increased by 25.52%,and air temperature increased by 2.12% in 21 years due to the expansion of construction land.The air temperature is positively affected by LH-NR and LH,and most obviously affected by LH-NR,but in cropland,air temperature is negatively affected by LH-NR.Precipitation is most affected by LH,that is,the two are the most closely related,followed by LH-NR.Therefore,when analyzing regional climate change,the effects of LH,NR and LH-NR on land surface temperature(LST)and climate factors under different land cover types cannot be ignored.This study emphasizes the mechanism of energy balance difference among different land cover types under the influence of human activities,explores the climate effect under the surface energy change in the whole Huang-Huai-Hai region.Discussing the climate warming or cooling effect along the Huang-Huai-Hai region in terms of the results of energy input by net radiation and energy output by latent heat flux respectively.Providing a theoretical basis for the trend of surface energy change in the Huang-Huai-Hai region and related factors affecting regional climate change.The results provide a theoretical basis for the analysis of surface energy trends and related factors affecting regional climate change.