An Estimation of Ocean Surface Heat Fluxes during the Passage of Typhoon at the Ieodo Ocean Research Station: Typhoon Lingling Case Study 2019

We investigated the strengthened ocean surface heat flux at Ieodo Ocean Research Station (Ieodo ORS) during the passage of Typhoon Lingling. On September 6, 2019, when Typhoon Lingling approached the Ieodo ORS, we observed a dramatic drop in the sea surface temperature (SST) of 5.0 °C along with intense turbulent mixing. Although the decline of the SST was much weaker than the observed data, the SST simulated by the regional air-sea coupled model exhibited a decrease of about 2.0 °C in a few hours due to turbulent mixing by current shear. At the same time, the latent heat flux showed a robust downward transfer. We also investigated the case with the air-sea coupled model and atmosphere-only model, but this negative latent heat flux was not captured. The sensible heat flux was better captured by the coupled model than the uncoupled model. And the coupled model simulated the latent heat flux closer to downward than the uncoupled model. We conducted a sensitivity test by altering the flux estimation methods used to estimate ocean heat fluxes. We found that the latent heat flux was more sensitive to the choice of estimation and showed much room for improvement. In this regard, the joint model-observation study using Ieodo ORS data provides an invaluable opportunity for improved typhoon simulation.