Land surface temperature variations in the Yunnan Province of Southwest China.

Abstract

High-altitude areas are thought to be more sensitive to climate change, but long-term series of land surface temperature (LST) observations are still inadequate in low-latitude high-altitude mountainous areas. We investigated spatiotemporal variations in the LST and its dominant driving factors at different time scales based on the long-term series (2001 - 2020) of MODIS data over the Yunnan Province (YNP) in southwest China, with a special focus on elevation-dependent warming (EDW). The results indicated that annual LST generally increased at a rate of 0.18°C decade-1 over the past 20years, and the increase was stronger in summer (0.47°C decade-1). Moreover, the nighttime warming rate (0.43°C decade-1) was much faster than that during the daytime (- 0.08°C decade-1), indicating that there was an asymmetric diurnal warming. We also confirmed the presence of EDW, which behaves more greatly above 3500m. Spatially, the warming trend in high-cold mountains, hot-dry river valleys and the tropics was obvious, while the trend in the northeastern YNP and western side of the Ailao Mountains was opposite. On the timescales of annual, autumn and winter, more than 60% of the LST in the study area was mainly affected by temperature, and 20% ~ 30% was affected by precipitation. LST and warming trend largely differenced with respect to land cover types, with the highest values occurring in built-up lands. This research is expected to contribute to a better understanding of climate change processes in the YNP.