The organization of tropical convection by intraseasonal sea surface temperature anomalies

The organization of convection by intraseasonal sea surface temperature (SST) anomalies is investigated to examine the role that atmosphere-ocean coupling may play in the maintenance of the Madden-Julian Oscillation. An atmospheric general-circulation model with an ocean-covered surface is used to investigate the response of tropical convection to idealized imposed intraseasonal SST anomalies, and the sensitivity of this response to their propagation speed. The convection is found to be organized on the spatial and temporal scales of the imposed SST anomalies and the location of the maximum in precipitation relative to the SST anomaly is in good agreement with observations, and different from that for a stationary SST anomaly. The magnitude of the precipitation anomalies increases with decreasing propagation speed of the SST anomalies. The role of the free-tropospheric humidity is crucial for determining the location and magnitude of the precipitation response.