Causes and predictability of the 2022 mega-flash drought over the Yangtze River basin

A mega drought occurred in the summer of 2022 over the Yangtze River basin in southern China, and affected 2.85 million hectares of crops and water supply for 4.73 million people. With the strongest rainfall deficit and hottest temperature since 1961, the drought developed from less than 20% of the basin at the beginning of July to more than 80% of the basin in the mid-August, which is an unprecedent flash drought in the Yangtze River basin. Here, we investigate multi-scale causes of the mega-flash drought including the land-atmospheric dry coupling at sub-seasonal time scale, the link with La Niña and PDO at interannual to decadal scales, and the effect of anthropogenic climate change. The subseasonal-to-seasonal (S2S) climate forecast models and the NMME seasonal prediction models will be used to assess the forecast skill of the drought onset, and a copula-based method will be implemented to predict the probability of drought recovery. Lastly, the future risk of the mega-flash drought will also be investigated by using CMIP6 models.