Intraseasonal variability in the Indian Ocean region

Ocean-atmosphere coupled feedbacks in the Indian Ocean and maritime continent on 30- to 90-day timescales play an important role in the maintenance and propagation of the atmospheric intraseasonal oscillation (ISO). Alternating patterns of reduced-cloud quiescent conditions and cloudy disturbed conditions modulate fluxes of freshwater, heat, and momentum to the upper ocean. The ocean responds to these forcings through changes to upper ocean stability, heat content, surface currents, and equatorial oceanic Kelvin and Rossby waves, which collectively regulate the sea surface temperature (SST). The SST response to atmospheric and oceanic intraseasonal variability spans diurnal to seasonal timescales and influences atmospheric convection through surface flux feedbacks. This chapter describes these multiscale coupled feedbacks and summarizes recent work that demonstrates the influence of seasonal-to-interannual ocean variability on mean state atmospheric moisture patterns, which play a prominent role in ISO propagation, and higher-frequency ocean variability that helps maintain the ISO cloud anomaly on intraseasonal timescales.