Record-breaking drought in southern China linked to Eurasian warming and tropical sea surface temperature

Southern China experienced an extreme drought that persisted from summer to autumn in 2022, ranking as the most severe drought since 1980. The reason for the occurrence of this extreme drought event was investigated. It shows that both the Eurasian warming and the tropical sea surface temperature (SST) played key roles in the occurrence of this event.

The work is published in the journal Science China Earth Sciences.

The drought in southern China during the summer of 2022 was strongly linked to the divergence of water vapor flux and descending motions, which resulted from the anomalous anticyclone over the western North Pacific and the northward movement of the East Asian subtropical jet, respectively. In comparison, the sustained drought in autumn was mainly influenced by the cyclonic circulation anomaly over the region from the Bay of Bengal to the South China Sea, which led to decreased moisture and descending motions in southern China.

The rarely strong Eurasian warming and the extreme La Niña-like pattern jointly resulted in the western North Pacific anticyclonic circulation anomaly and the northward shift of the East Asian subtropical jet during summer, while the cyclonic circulation anomaly prevailing over the region from the Bay of Bengal to the South China Sea in autumn was largely attributed to the extremely negative SST anomalies in the tropical Indian Ocean.

The findings are expected to deepen the understanding of physical mechanisms underlying the persistent droughts and provide scientific basis for disaster prevention and mitigation, since Southern China has suffered from frequent occurrences of droughts after entering into the 21st century.