This paper reveals a strong in-phase covariability of tropical cyclone (TC) activity between the Bay of Bengal (BOB) and the South China Sea (SCS) during October–December (1979–2019). This dominant mode accounts for 35% of the total variance in TC track density and is closely linked to tropical sea surface temperature anomalies, specifically the Indo-Pacific Tripole mode. This mode significantly affects atmospheric circulations, modulating local TC genesis frequency in both basins. Migrated TCs are primarily affected in their genesis location, not frequency. Even excluding SCS-to-BOB migrating TCs, the inter-basin covariability remains significant. Numerical simulations suggest the Pacific Ocean's influence is twice as important as the Indian Ocean's.

Zeming Wu, Chundi Hu, Lifei Lin, Weizhen Chen, Lixuan Huang, Zijian Lin, Song Yang