[A-CG40] Earth System Observation Impacts on Climate and Ocean Predictions

[ACG40-09] Sensitivity analysis and data assimilation across the sea surface around tropical cyclones

★Invited Papers

*Kosuke Ito^1,2 (1.Disaster Prevention Research Institute, Kyoto University, 2.Yokohama National University)

Keywords:tropical cyclone, adjoint-based sensitivity, coupled model

A tropical cyclone (TC) is a phenomenon in which surface-heat-induced diabatic heating plays an essential role. Under strong winds, sea surface temperature (SST) decreases by 1–6 K on a time scale of several hours to a few days due to shear-induced entrainment at the base of the ocean mixed layer and the oceanic Ekman pumping. Therefore, it is important to precisely observe the oceanic conditions during the passage of the TC.

In this presentation, we would like to present the importance of oceanic conditions to the track and intensity of TCs based on coupled and atmospheric modelling studies, sensitivity analysis and data assimilation. For example, the coupled model dramatically improves the TC intensity forecast quality. The adjoint-based sensitivity analysis with an idealized axisymmetric model showed that a maximum wind can respond to the surface heat and momentum flux in a time scale of local inertial period (~1 h). The coupled data assimilation exhibits that an SST observation can impact on the temperature profile within the atmospheric boundary layer. We will also explain the recent activities on the sensitivity and data assimilation of surface observations.