Does drought show a significant weakening trend from 1961 to 2017 in northern China?

Understanding the multi-dimensional drought variation and its driving mechanism is essentially important in climate change and risk assessment. Based on the monthly meteorological data at 321 stations from northern China, this study computed the Standardized Precipitation Evapotranspiration Index (SPEI), which was estimated using the potential evapotranspiration (PET) with the Penman-Monteith equation. Drought displayed the wetting trend in 1961-2017 at a rate of 0.05/10a, which generally occurred in winter and in most study areas. In contrast, the apparent drying trend occurred on the Loess Plateau. The piecewise linear regression method (LRM) identified that the turning point (TP) for trends occurred in 1990; the annual SPEI had been increasing pre-1990 and decreasing post-1990. This was especially the case in the Xinjiang Uygur Autonomous Region, Tibet, Gansu, and Inner Mongolia, consistent with patterns of seasonal drought at their respective TP apart from autumn. From 1961 to 2017, the drought-affected area decreased at a rate of - 1.69%/10a (p < 0.05). The area decreased before the TP and increased after the TP at different drought levels. The seasonal drought-affected area also showed decreasing trend, particularly in winter. The highest frequency and duration of drought occurred in the Loess Plateau and Xinjiang Uygur Autonomous Region, respectively, although it decreased post-1990. These findings suggest that long-term trends in drought were not significant in northern China during 1961-2017. Although the severity, frequency, and duration of drought decreased post-1990, the recent increasing drying trend and drought-affected area should not be dismissed.

Automated summary

Understanding the multi-dimensional drought variation and its driving mechanism is important for climate change and risk assessment. This study analyzed the drought trends in northern China from 1961 to 2017 using the Standardized Precipitation Evapotranspiration Index (SPEI). The results showed that the long-term drought trends were not significant during the study period, but there was an increasing drying trend and expanding drought-affected area in recent years. Winter was the season with the most severe drought, and the Loess Plateau exhibited the most prominent drying trend.