Parameterizing Sea Surface Temperature Cooling Induced by Tropical Cyclones: 1. Theory and An Application to Typhoon Matsa (2005)

Sea surface temperature cooling (SSTC) induced by tropical cyclones (TCs) could produce a significant impact on the TC intensity. Although a coupled atmosphere-ocean model could provide such SSTC, various challenges associated with coupled modeling often lead many TC researchers to continue to use atmosphere-only models. Therefore, 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 atmosphere-only TC 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 idealized ocean simulation, a new SSTC parameterization scheme including vertical mixing, advection, and SST recovery processes under the influences of sea surface height anomalies and ocean subsurface temperature is developed; and (iii) this SSTC parameterization scheme is evaluated through numerical simulations of Typhoon Matsa (2005) and validated against remote sensing data. Results show significant improvements in the simulated TC intensity and 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. Plain Language Summary It is well known that tropical cyclones (TCs) may induce local cooling in sea surface temperature (SST), through upwelling of cold water from underneath, which would in turn act to slow down TC intensification. So it is highly desirable to incorporate the fine-scale structures of the TC-induced SST cooling into numerical TC models in order to improve the prediction of TC intensity. In this study, we developed an easy-to-use, fast, and effective parameterization scheme for TC-induced SST cooling that can be used in atmosphere-only TC models. Results show significant improvements in the simulated TC intensity and SST changes after applying this parameterization scheme. Although further testing with more TC cases is needed, the parameterization scheme should be compatible with any TC weather prediction model.