资源环境科技发展态势分析平台

Using observed data sets, an unprecedented multiple tropical cyclogenesis event over the northwest Pacific is identified, with seven tropical cyclones forming in sequence from 6 August to 10 September 2004. In this event, the preexisting tropical cyclones (TCs) generated the alternating cyclonic and anticyclonic disturbances in their wake region by exciting Rossby waves. The cyclonic disturbances subsequently intensified into new TCs within the monsoon trough, which was likely enhanced by anomalous warming in the tropical central Pacific and cooling in the tropical Indian Ocean, so that it lasted long enough to allow seven TCs to develop consecutively. An analysis of the historical records during 1979-2014 substantiates such linkage of the occurrence of this extreme multiple tropical cyclogenesis event to the anomalous sea surface temperature pattern and the monsoon trough. This result has important implications regarding the prediction of the multiple cyclogenesis events.

Plain Language Summary Tropical cyclones (TCs) are severe weather phenomenon, with important role in modulating regional and global climate. TC-induced extreme events often bring huge disasters to human society. This study has identified a hitherto unreported extreme event that seven TCs clustered together over the northwest Pacific in the late summer of 2004. The number of TCs in this event is the highest among the recorded multiple tropical cyclogenesis events (MTCEs). This study shows that the occurrence of this extreme MTCE is partly caused by the anomalous warming in the tropical central Pacific and cooling in the tropical Indian Ocean in the summer of 2004. Historical record further confirms that the anomalous sea surface temperature pattern increases the possibility in the occurrence of MTCEs. The result has important implications to improve the prediction skill of extreme MTCEs.