[A-AS02] Advances in Tropical Cyclone Research: Past, Present, and Future

[AAS02-18] Validation of the PWP ocean mixed layer model and its improvements for Tropical Cyclone forecast simulations

Jumpei Furukawa¹, *Yutaka Yoshikawa¹ (1.Graduate School of Science, Kyoto University)

Keywords:ocean surface mixing, SST change, PWP model validation, wave-induced mixing

Ocean surface mixing changes sea surface temperature (SST) and then affects tropical cyclones (TCs) intensity. Recent TC forecast models attach the ocean mixing model to improve TC forecast skills. Among several ocean mixing models/schemes, Price-Weller-Pinkel (PWP) model (Price et al. 1986), which was originally developed for observed mixed layer diurnal variations, is widely used for the TC models because of its small numerical costs, though it has not been fully validated so far. Some recent field experiments measuring the ocean surface mixing and subsequent SST changes suggest that the PWP model tends to underestimate the mixing particularly when surface wave-induced mixing is expected to dominate. In this study, we made extensive and systematic validation of the PWP model, using large-eddy simulations run with the same conditions with those of the PWP model, to realistically simulate the ocean surface mixing and SST changes. The model ocean was forced by typical axi-symmetric TC wind (Holland 1980) passing over the model domain (750m x 750m x 300m) with a constant transition speed and surface waves generated by the wind. Comparison between the PWP model results and LES results shows that the PWP model successfully reproduces the SST changes if the wind-induced mixing dominates, but it fails if the wave-induced mixing dominates. We will suggest a possible way of the PWP model improvement for the wave-induced mixing.