Remote effect of a tropical cyclone in the Bay of Bengal on a heavy-rainfall event in subtropical East Asia

Torrential frontal rainfall occurred over Northern Taiwan on June 2, 2017. Prior to this rainfall, tropical cyclone (TC) Mora formed in the Bay of Bengal. This study investigated the triggering effect of TC Mora on the heavy-rainfall system through numerical experiments. The numerical experiments, in which TC Mora was included or excluded in the initial conditions, revealed that TC Mora strengthened the southwesterly winds, which effectively transported tropical warm moist air toward Taiwan, and the cool dry northerly winds to the north of Taiwan. The strengthened southeasterly and northerly winds created a strong frontal system near Taiwan. TC Mora contributed to the heavy frontal rainfall by enhancing tropical–extratropical interaction and vertical coupling in East Asia.