Enhanced Oceanic Environmental Responses And Feedbacks To Super Typhoon Nida (2009) During The Sudden-Turning Stage

The ocean surface and subsurface biophysical responses and their feedbacks to super typhoon Nida were comprehensively investigated based on a substantial dataset of multiple-satellite observations, Argo profiles, and reanalysis data. Nida experienced two Category 5 stages: a rapid intensification stage that was fast moving along a straight-line track, and a rapid weakening stage that was slowly moving along a sharp-left sudden-turning track. During the straight-line stage, Nida caused an average sea surface temperature (SST) cooling of 1.44 degrees C and a chlorophyll-a (chl-a) concentration increase of 0.03 mg m(-3). During the sudden-turning stage, cyclonic sudden-turning induced a strong cold cyclonic eddy (SSHA < -60 cm) by strong upwelling, which caused the maximum SST cooling of 6.68 degrees C and a long-lasting chl-a bloom of 0.6 mg m(-3) on the left-hand side of the track, resulting in substantial impacts on the ocean ecological environment. Furthermore, the enhanced ocean cold wake and the longer air-sea interaction in turn decreased the average inner-core SST of 4 degrees C and the corresponding enthalpy flux of 780 W m(-2), which induced a notable negative feedback to the typhoon intensity by weakening it from Category 5 to Category 2. The left bias response and notable negative feedback are special due to sharp-left sudden-turning of typhoon. Comparing with the previously found slow translation speed (similar to 4 m s(-1)) of significant ocean response, the negative feedback requires even more restriction of translation speed (<2 m s(-1)) and sharp sudden-turning could effectively relax restrictions by making equivalent translation speed lower and air-sea interaction time longer. Our findings point out that there are some unique features in ocean-typhoon interactions under sudden-turning and/or lingering tracks comparing with ordinary tracks.