Multiscale Interactions over the Maritime Continent: Feedbacks between Atmospheric Convectively Coupled Kelvin Waves and Diurnal Cycle

Abstract:

Interactions between atmospheric convectively coupled Kelvin waves (CCKW), initiated over the Indian Ocean, and the diurnally varying convection over the Maritime Continent are primary interest of this presentation. Mutliscale interactions between local and propagating convection lead to substantial enhancement of the local diurnal cycle over that region. CCKW activity strongly modulates magnitude of the diurnal cycle of precipitation over the Maritime Continent, but not its temporal evolution, which maintains characteristics of a diurnal cycle. The impact is such that precipitation is highly increased during convective part of the CCKW and little suppressed during its non-convective part. Timing of the increase in diurnal cycle magnitude strongly depends on the time of the day of the CCKW approach to the Maritime Continent. It is shown that precipitation anomaly associated with CCKW is phase locked with local diurnal cycle of precipitation over the Maritime Continent and that has implications for CCKW ability to propagate across that region. The composite daily-zonal evolution of the precipitation anomaly associated with CCKW is such that it is “in-phase” with local diurnal cycle over Sumatra, Borneo and surrounding seas.

This presentation is based on analysis of TRMM precipitation data and newly developed CCKW trajectories database.