Analysis of the relationship between vegetation phenology and the surface thermal environment based on the downscaling of land surface temperature
Vegetation phenology is the phenomenon of periodic changes in vegetation as it is affected by the external environment,and is a key indicator of the impact of climate change on ecosystems.Under the influence of arid climate,the sub-surface of the arid zone warms up rapidly and has a strong heat storage capacity,and the influence of the continuously rising land surface temperature on the vegetation phenology should not be neglected.In this paper,the spatial distribution pattern of vegetation phenology and land surface temperature from 2002 to 2021 was investigated using MODIS remote sensing images MOD11A1 and MOD13Q1 in the urban agglomeration of the north slope of Tianshan Mountains as the study area.Random forest regression model was selected to downscale land surface temperature,and the Mann-Kendall non-parametric test and Theil-Sen slope were used to analyze the changing trend of vegetation phenology over the past 19 years.The effects of air temperature,elevation,evapotranspiration,land surface temperature,precipitation,soil moisture and atmospheric aerosols on vegetation phenology were analyzed based on the Spatial Durbin Model(SDM).Finally,the local correlation between land surface temperature and vegetation phenology was explored.The results show that the accuracy of the land surface temperature downscaling results is high,and the R2 values of the daytime and nighttime LST are 0.982 and 0.985,respectively,which can reflect more details of the features.The land surface temperature varies greatly between daytime and nighttime,showing"cold island"and"hot island"phenomena,respectively.The start of season time(SOS)is advanced,the end of season time(EOS)is delayed,and the length of season time(LOS)is extended.The more significant changes in vegetation phenology were concentrated in oases,while the changes in non-oasis areas were less significant.Temperature,evapotranspiration,and precipitation all have a great impact on various indicators of vegetation phenology.Among them,the effect of land surface temperature on vegetation phenology is more typical.The results of this paper are of great significance for understanding the complex mechanisms of vegetation phenology changes in oases in arid zones,and for maintaining the sustainable development of oasis resources.
land surface temperaturevegetation phenologydownscalingSpatial Durbin ModelMann-Kendall nonparametric testTheil-Sen slope
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