The Variation of Compound Warm Dry Extremes Over Eastern China and the Associated East Asian Subtropical Jet in the Boreal Summer

Abstract

AbstractThe compound warm dry extremes (CWDEs), which can lead to extreme impacts that are much larger than the sum of the impacts due to the occurrence of individual extremes alone, have frequently hit the land regions. In this study, the spatial‐temporal variations of the frequency, warm, and dry intensity of the CWDEs over eastern China and the associated East Asian subtropical jet variations have been investigated. The results show that the first two leading CWDE frequency modes over eastern China are characterized by an increase pattern and a dipole pattern. The increases in the CWDE frequency may be accompanied by both the strong warm and dry in the northern part of China. Whereas, these may be mainly related to the strong warmth in the southern part of China. The dominant increase pattern is associated with the weakened land‐branch East Asian subtropical jet, which is maintained by the negative phase of the interdecadal Pacific Oscillation, the warming over high‐latitudes of the Atlantic Ocean and the positive phase of the Arctic Oscillation. The dipole pattern is related to the southward shift of the ocean‐branch East Asian subtropical jet, which is sustained by the warming in central equatorial Pacific and Indian Oceans, as well as the negative phase of North Atlantic Oscillation and the Pacific‐Japan teleconnection. The relative contribution analysis has confirmed the importance of the jet variations to the CWDEs. These results would be helpful for understanding the drivers of the CWDEs.