Parameterizing Sea Surface Temperature Cooling Induced by Tropical Cyclones

Sea surface temperature cooling (SSTC) induced by tropical cyclones (TCs) could produce a significant impact on the storm intensity. Although a coupled air-sea interaction model could provide such SSTC, its accurate application is often a challenge due to various complexities involved. The main goal of this study is to develop a fast, robust, and effective parameterization scheme for TC-induced SSTC that can be used in TC weather prediction models. The following three steps are taken to achieve this goal: (i) results from an idealized ocean simulation, together with theoretical and temperature budget analyses, are analyzed to isolate each major mechanism causing TC-induced SSTC, which is then used as a basis for the parameterization; (ii) building upon the SSTC parameterization schemes appearing in the literature, this new SSTC parameterization scheme includes vertical mixing, advection, and SSTC recovery processes under the influence of sea surface height and ocean subsurface temperature; and (iii) the TC-induced SSTC scheme is incorporated into the Weather Research and Forecast model, and then validated against various remote sensing and in situ data through numerical simulations of Typhoon Matsa (2005). Results show significant improvements in the simulated storm intensity and reasonable SST changes after applying this parameterization scheme. Although further testing with more TC cases is needed, these results are promising, and the parameterization scheme should be compatible with any TC weather prediction model. This scheme can also produce the realistic distribution of TC-induced ocean-surface circulations in relation to SSTC during and after TC passage.