This study investigates upper ocean response to Super typhoon Hai-Tang, the most intense typhoon in 2005, in the western North Pacific using multi-satellite microwave data, typhoon data and Argo profiles. Sequential merged microwave sea surface temperature (SST) images show that Hai-Tang induced four separately cooling responses after its trail in the western North Pacific during 11 - 18 July. Comparison between upper ocean responses of cooling SST and pre-typhoon sea surface height suggests that these cooling responses of the upper ocean to Hai-Tang are closely associated with pre-existing cyclonic circulation denoted by pre-existing negative sea surface features. Furthermore, applying Argo profiles, the physical mechanism is confirmed to be associated with pre-existing cyclonic circulations provide a relatively unstable thermodynamic structure, and therefore cold water would be brought up readily. This paper provides the rather convincing evidence that cyclonic flow and uplifted thermocline are the pre-existing conditions for intensive cooling following the typhoon passage.
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