Dynamical propagation and growth mechanisms for convectively coupled equatorial Kelvin waves over the Indian Ocean

Convectively coupled equatorial Kelvin waves (CCKWs) are high-impact tropical weather systems that can lead to severe flooding over the Maritime Continent. Here, a vorticity budget for CCKWs Indian Ocean is constructed using reanalysis data, identify basic mechanisms of eastward propagation and growth. The reasonably well closed, with small residual/subgrid-scale term. In lower troposphere, behave like strongly modified theoretical waves. Vortex stretching, from divergence wave acting on planetary (the − f D term), sole mechanism by which structure propagates eastward. middle this term also key but, due subtleties in its phasing linked combination modal structures, it contributes Unlike wave, other source terms play role growth CCKWs. particular, vortex stretching relative ζ term) largest term, leads growth, through interactions between background perturbation divergence. Horizontal advection flow propagation, acts retard CCKW. sum complex upper troposphere quite unlike appears arise as forced response lower-tropospheric structure. implications numerical prediction climate simulations discussed.