Simulation of the South American climate by a coupled model with super-parameterized convection

Abstract

The simulation of the climate over South America by a coupled ocean–atmosphere model with embedded cloud resolving model is studied on different time scales. The mean climate and the variability over South America as simulated by the superparameterized Community Climate System Model version 3 (SP-CCSM) are compared with those in the observation and in the control simulation of the CCSM3 (CT-CCSM) which employs conventional scheme of convection parameterization. The CT-CCSM is able to simulate only the longer period seasonal oscillation (SO) while the SP-CCSM is successful in simulating both the SO and the intraseasonal oscillation (ISO). The spatial structure and the propagation of the oscillations are better in the SP-CCSM. Both models are able to simulate the observed low-frequency modes of variability related to El Nino-Southern oscillation (ENSO) and Pacific decadal oscillation (PDO). While the ENSO mode in the CT-CCSM has more regular variability with a biennial time scale, the SP-CCSM simulates the ENSO mode with more irregular variability and time scale closer to the observation. The spatial structure, the relation with the Pacific and the regional variations of the observed PDO mode are better simulated by the SP-CCSM than the CT-CCSM.