Radiation, Convection, and Circulation Feedbacks Associated with the Madden-Julian Oscillation

Monday, 15 December 2014: 5:33 PM
Xianan Jiang, JIFRESSE/UCLA, Pasadena, CA, United States
The Madden-Julian Oscillation (MJO) exerts pronounced influences on global climate and weather systems, yet its representation in global climate and NWP models remains a great challenge. Also the fundamental physics of the MJO are still elusive. In this talk, by analyzing multi-model climate simulations from the WCRP-WWRP/THORPEX YOTC MJO Task Force and GEWEX GASS global model inter-comparison project, roles of radiative heating and convection-circulation feedback for the MJO will be discussed under a framework of the gross moist stability analysis. While not directly responsible for the model MJO performance, the strength of the cloud-radiative feedback as denoted by the radiative versus convective heating ratio is significantly associated with amplitude of the intraseasonal variability in a model. In agreement with several previous studies, analysis also suggests that the net moist energy import to the atmospheric column by convection-induced circulation could be critical for sustaining the MJO.