Maintenance of convectively coupled Kelvin waves: relative importance of internal thermodynamic feedback and external momentum forcing

Mu-Ting Chien , Daehyun Kim, Patrick Haertel

Previous studies suggest that convectively coupled Kelvin waves (KWs) are likely maintained by two distinct processes: (1) the internal thermodynamic feedback between KW diabatic heating and temperature and (2) the external momentum forcing from the midlatitude Rossby waves exerting on KW zonal wind. This study quantifies the relative importance of the two processes on KW maintenance by comparing the growth rates of eddy available potential energy (EAPE) and eddy kinetic energy (EKE) within KWs using satellite and reanalysis data. Results show KWs are maintained primarily by the internal thermodynamic feedback in all regions and seasons, especially over the Indian Ocean, where the mean state sea surface temperature is the highest, and the upper tropospheric westerly is the weakest. Overall, the observed relative importance of the two maintenance processes can serve as a reference for numerical simulations of KWs.