An Extreme Drought over South China in 2020/21 Concurrent with an Unprecedented Warm Northwest Pacific and La Niña

An extreme drought appeared in South China from October 2020 to March 2021.During that time,sea surface temperatures exhibited an unprecedented warm center over the northwest Pacific(NWP)and a cold center over the tropical eastern Pacific(La Niña).This study demonstrates the combined effects of an exceptionally warm NWP and a moderate La Niña are closely linked to the anomalous drought in South China.The sea surface temperature anomaly in these two regions induced a steeper horizontal geopotential height gradient over South China.As a result,anomalous northeasterly winds prevailed over South China,altering water vapor transport and moisture convergence.A simplified atmospheric general circulation model also verifies the influence of the NWP warm anomaly on South China precipitation.This study points out that the sea surface temperature variation in the NWP was important to the occurrence of extreme drought in South China from October 2020 to March 2021.