Analysis of land surface temperature variation based on MODIS data a case study of the agricultural pastural ecotone of northern China

Abstract

The agricultural pastural ecotone of northern China (APENC), as one of the world’s four agro-pastural ecotones, is a typical fragile ecological zone and sensitive zone responding to global climate change. The thermal environment pattern of APENC has been dramatically changed due to intensive human disturbances, especially the land use/land cover change induced by a series of ecological restoration projects implementation after 1999. Few studies focused on land surface temperature (LST) variation in this region due to the lack of long time series remote sensing data. The spatial, temporal and trend characteristics of LST were quantitatively analyzed at different timescales based on a long-term sequence of MODIS data in APENC (2003–2020). Results showed that (i) the thermal pattern of APENC was dominated by high LST areas and very high LST areas at an annual and seasonal timescale. These regions mainly distributed in Yellow River Basin, southeast boundary and vast plains in the northeast. The high value of absolute variability (AV) mainly occurred in the western of Yinshan-Greater Khingan Mountains and northeast of APENC. Meanwhile, the AV was largest in winter and then decreased from spring to fall. The fluctuation degree of AV was largest in summer while the slightest in fall. (ii) The LST exhibited insignificantly and rapidly warming during 2003–2007 and 2012–2014, respectively. Whereas the significant cooling trend occurred during 2007–2012 and 2014–2020. (iii) The LST showed a warming trend at an annual, spring and winter timescale since the increasing trend in nighttime was faster than the decreasing trend of LST in daytime. The cooling trend occurred in fall and summer because the decreasing range of LST in daytime was greater than the increasing nighttime trend. These results will provide an important regional demonstration for climate change study of arid and semi-arid region and a reference for agricultural and livestock production for APENC.