Climatology of sub-monthly wave patterns associated with tropical cyclone tracks over the East Asian monsoon area during July-August season
Ken-Chung Ko, National Kaohsiung Normal Univ., Kaohsiung, Taiwan; and H. H. Hsu
This study explores the sub-monthly circulation features in the western North Pacific during July and August. The sub-monthly wave-like pattern propagates northnorthwestward from the southeastern Philippine Sea to East China. The wavelength is about 4000 Km and the phase speed is about 5m/s. This feature fluctuates in a 10-25 day timescale with a spectral peak at 12.5 days. More than seventy percent of the chosen cases occur concurrently with recurving tropical cyclones, which propagate along with the wave-like pattern. Therefore, these recurving tropical cyclones are part of the wave-like pattern instead of isolated vortices. The wave-like pattern occurs in a large-scale flow characterized by an enhanced monsoon trough that extends eastward into the Philippine Sea, and a strong ridge protruding westward from the subtropical high. It is suggested that the cyclonic phase of the wave-like pattern provides a favorable environment for the genesis, growth, and propagation of the recurving tropical cyclones.
Joint Poster Session 2, Model Diagnostics and General Climate Variability (Joint with Climate Change Manifested by Changes in Weather and 19th Conference on Climate Variability and Change)
Monday, 15 January 2007, 2:30 PM-4:00 PM, Exhibit Hall C
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