1:45 PM - 2:00 PM
[AOS14-01] LES-based validation of the PWP-model simulation of ocean surface mixing and sea surface temperature decrease during tropical cyclone passage
Keywords:Tropical cyclone, PWP model
Tropical cyclones (TCs) develop by obtaining sensible heat released from the warm ocean surface. Developed TCs on the other hand induce intense turbulent mixing below the sea surface, causing the sea surface temperature (SST) decreases due to the mixing with cold water at depth, resulting in suppressing the TC development. In order to predict these TC life cycles, an ocean mixing model that can appropriately represent the TC-induced mixing in the surface ocean and consequent SST decreases is necessary.
Recently, the PWP model (Price et al. 1986), the model that represents ocean surface mixing with relatively simple mixing parameterization, has been introduced as an ocean model into the JMA's TC forecasting system, and improve the forecasting skills (Annual Report of Numerical Prediction Development Center, JMA, 2021). These results are encouraging, however, we think more careful examinations of the PWP model simulations are required because simple mixing parameterization of the PWP model may fail to reproduce complicated ocean mixing processes in certain conditions.
Here, we used the 1D PWP model to simulate the surface mixing and resultant SST decreases caused by prescribed TC passing over the stratified ocean. Then the simulated results were compared with those simulated with the 3D Large-eddy simulation (LES) that is assumed to produce the mixing and reduction realistic. The simulations were done with several sets of translation speed, density stratification and latitudes. The results show that the PWP overestimates SST decreases in almost all cases, and that the overestimation is larger for the faster translating TC and for the stronger ocean stratification. Detailed mechanisms of these results will be discussed in the meeting.
Recently, the PWP model (Price et al. 1986), the model that represents ocean surface mixing with relatively simple mixing parameterization, has been introduced as an ocean model into the JMA's TC forecasting system, and improve the forecasting skills (Annual Report of Numerical Prediction Development Center, JMA, 2021). These results are encouraging, however, we think more careful examinations of the PWP model simulations are required because simple mixing parameterization of the PWP model may fail to reproduce complicated ocean mixing processes in certain conditions.
Here, we used the 1D PWP model to simulate the surface mixing and resultant SST decreases caused by prescribed TC passing over the stratified ocean. Then the simulated results were compared with those simulated with the 3D Large-eddy simulation (LES) that is assumed to produce the mixing and reduction realistic. The simulations were done with several sets of translation speed, density stratification and latitudes. The results show that the PWP overestimates SST decreases in almost all cases, and that the overestimation is larger for the faster translating TC and for the stronger ocean stratification. Detailed mechanisms of these results will be discussed in the meeting.