Guan'gai paishui xuebao (Jan 2022)
Changes in Surface Temperature of Sandy Soil in Mu Us in Xinxiang and Its Underlying Determinants
Abstract
【Objective】 Soil surface temperature is a factor affecting not only surface evaporation but also physical and biogeochemical processes in soil. Its change depends on many factors and varies with both spatial and temporal scales. The aim of this paper is to analyze the evolution of surface temperature of sandy soils at Mu Us in Xinjiang province over the past decades, as well as the impact of climate change and restoration of grassland to forests on it. 【Method】 The analysis was based on monthly average temperature in the MOSLT1M database (China), and the geospatial data, including temperature, taken from MOD11A2 in the MODIS/TERRA satellite images of NASA. The resolution of all datasets was 1km. Spatiotemporal changes in the surface temperature from 2000 to 2019 was first analyzed using linear regression slope method, and we then calculated its correlation with climatic factors, land usage and vegetation index. 【Result】 Spatially, the surface temperature varied erratically but with an average trend of declining from northwest towards southeast. Temporally, the temperature had been in decline at a rate of 0.59 ℃ per decade from 2000 to 2019. Changes in annual average and fluctuation of the temperature were consistent. During each of the following three periods: 2000—2005, 2005—2009 and 2009—2013, the average temperature dropped first followed by an increase. Change in land usage had a noticeable impact, with the temperature being the highest on construction land and bare land, the lowest in cultivated land and water body, and that on grassland and forest in between. The temperature was negatively correlated with the trend of NDVI, with a coefficient of determination of 0.513 1. Spatiotemporal variation of the temperature is inconsistent with the change in global warming due to anthropogenic activities such as change in land usage. 【Conclusion】 The spatiotemporal variation of soil surface temperature from 2000 to 2019 in Mu Us in Xinjiang province is a result of the combined influence of human activities and climate change, with the former being more significant than the latter.
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