Observational and modeling studies of oceanic responses and feedbacks to typhoons Hato and Mangkhut over the northern shelf of the South China Sea

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Dong, W., Feng, Y., Chen, C., Wu, Z., Xu, D., Li, S., Xu, Q., Wang, L., Beardsley, R. C., Lin, H., Li, R., Chen, J., & Li, J. Observational and modeling studies of oceanic responses and feedbacks to typhoons Hato and Mangkhut over the northern shelf of the South China Sea. Progress in Oceanography, 191, (2021): 102507, https://doi.org/10.1016/j.pocean.2020.102507.Meteorological and oceanic responses to Typhoons Hato and Mangkhut were captured by storm-monitoring network buoys over the northern shelf of the South China Sea. With similar shelf-traversing trajectories, these two typhoons exhibited distinctly different features in storm-induced oceanic mixing and oceanic heat transfer through the air-sea interface. A well-defined cold wake was detected underneath the storm due to a rapid drop in sea surface temperature during the Hato crossing, but not during the Mangkhut crossing. Impacts of oceanic mixing on forming a storm-produced cold wake were associated with the pre-storm condition of water stratification. In addition to oceanic mixing produced through the diffusion process by shear and buoyancy turbulence productions, the short-time scale of mixing suggested convection/overturning may play a critical role in the rapid cooling at the sea surface. The importance of convection/overturning to mixing depended on the duration of atmospheric cooling above the sea surface-the longer the atmospheric cooling, the more significant effect on mixing. Including the oceanic mixed layer (OML) in the WRF model was capable of reproducing the observed storm-induced variations of wind and air pressure, but not the air and sea surface temperatures. Process-oriented numerical experiments with the OML models supported both observational and modeling findings. To simulate the storm-induced mixing in a coupled atmospheric and oceanic model, we need to improve the physics of vertical mixing with non-hydrostatic convection/overturning. Warming over the shelf is projected to have a more energetic influence on future typhoon intensities and trajectories.This work was supported by the National Key Research and Development Programs of China with grant numbers 2018YFC-1406201; 2016YFA-0602700; 2018YFC-1506903; 2018YFC-1406205, and the National Sciences Foundation of China with grant number U1811464. S. Li was supported by the oversea Ph.D. fellowship from the China Scholarship Council (No. 1409010025) and Dr. Chen’s Montgomery Charter Chair graduate education funds at the University of Massachusetts-Dartmouth