Analysis of Drought Characteristics and Causes in Yunnan Province in the Last 60 Years (1961–2020).

Droughts are becoming more frequent and severe in southwest China, with Yunnan being the most affected region. Most of the current studies on droughts in Yunnan are limited to individual cases and lack a common determination of the causes of historical drought events. In this study, we analyzed drought characteristics and causes over the last 60 years (1961–2020) in Yunnan Province in two seasons: dry and rainy. There was a clear trend of aridity in Yunnan Province in terms of both temporal and spatial changes, and there was a long-term drought period in approximately 2010; in particular, the frequency of drought in the dry season significantly increased. Due to its unique geographical location, precipitation in Yunnan Province is influenced by various factors, and the main influencing factors differed in different periods. SST variation is the most important factor affecting Yunnan drought. Precipitation in Yunnan Province is affected by the warm pool of the Indian Ocean throughout the year, and thermal anomalies in different locations of the Pacific Ocean have different effects on Yunnan Province and often overlap with the effects of SST anomalies in the Indian Ocean. Significance Statement: In this study, we analyzed drought characteristics and causes over the last 60 years (1961–2020) in Yunnan Province in two seasons: dry and rainy. The causes of historical drought events in Yunnan Province in terms of common characteristics were determined, and SST variation was the most influential factor, with the Indian Ocean and the Pacific Ocean having the greatest influence. Increased temperature may be a more important cause of dry season drought in Yunnan Province, while drought in the rainy season is mainly due to reduced water vapor transport. These results point the way toward better understanding of the occurrence of drought in Yunnan Province. [ABSTRACT FROM AUTHOR]