The Cold Vortex Circulation over Northeastern China and Regional Rainstorm Events

In this study, regional rainstorm events (RREs) in northeastern China associated with the activity of the Northeastern China Cold Vortex (NCCV) were investigated on a medium-range time scale. The RREs occurring in northeastern China could be categorized into three groups according to the distribution of heavy rainfall. The largest cluster is characterized by the rainstorm events that occur on the northwestern side of the Changbai Mountains along a southwest-northeast axis. These events occur most frequently during the post-meiyu period. The authors place particular emphasis on the RREs that belong to the largest cluster and are closely associated with the activity of the NCCV. These RREs were preconditioned by the transportation of substantial amounts of water vapor to which the anomalous western Pacific subtropical high (WPSH) contributed. The attendant anomalous WPSH was primarily driven by the anomalous transient eddy feedback forcing the nearby East Asian jet. The development of the NCCV circulation was concurrent with the RREs and acted as their primary causative factor. A perspective based on low-frequency dynamics indicates that Rossby wave packets emanated from the blocking-type circulation over northeastern Asia led to the development of the NCCV activity.