Spatio-Temporal Patterns of Warm-Season Ground Surface Temperature-Surface Air Temperature Difference over China Mainland

Examining large-scale characteristics of the difference between ground surface temperature (GST) and surface air temperature (SAT) and its long-term trend will help understand land surface energy exchange and the effect of land-atmosphere interaction on climate change and variability. Based on a homogenized monthly dataset of GST and SAT from 1961 to 2018, this study analyzes the spatial distribution and long-term trend of the difference between ground surface temperature and surface air temperature (GST-SAT) in the warm season (April to October) over China mainland. The results show that the warm-season mean GST-SAT in the Qinghai-Tibet Plateau and the northwestern deserts have the largest GST-SAT. On average, the GST-SAT in China is the greatest in summer, with the maximum monthly value occurring in July. During 1961-2018, the warm-season mean GST-SAT undergoes a significant increasing trend (0.04 degrees C/10yr, p < 0.01), with the largest increase seen in mid-late spring (April and May), and the smallest increase in August. Spatially, the GST-SAT increases significantly in the northern region, decreases slightly in the southern region, and remains unchanged in the Qinghai-Tibet Plateau. The warm-season mean GST-SAT is significantly positively correlated with altitude and sunshine duration (R = 0.50, 0.40; p < 0.05), and significantly negatively correlated with relative humidity and precipitation (R = 0.48, 0.42; p < 0.05), in the country on a whole in the analysis period.

Automated summary

By analyzing the spatial distribution and long-term trend of the difference between ground surface temperature (GST) and surface air temperature (SAT) in China from 1961 to 2018, this study reveals that the Qinghai-Tibet Plateau and the northwestern deserts have the largest GST-SAT in the warm season. The GST-SAT is greatest in summer, with the maximum monthly value occurring in July. The warm-season mean GST-SAT has a significant increasing trend, with the largest increase in mid-late spring and the smallest increase in August.