Importance of pre‐existing oceanic conditions to upper ocean response induced by Super Typhoon Hai‐Tang

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.