[AAS05-01] The Madden-Julian Oscillation and Climate Change
Keywords:Intraseasonal variability , Climate Change , Madden-Julian oscillation , Climate modeling
Finally, an aquaplanet version of the NCAR Community Atmosphere Model run in uncoupled mode and coupled to a slab ocean is used to better understand physical processes underlying changes in MJO behavior in a warmer climate. MJO changes are minimal when 4xCO2 forcing is applied but surface temperatures are held fixed at 1xCO2 conditions, indicating that MJO changes in a warmer climate are primarily driven by the SST change. The MJO propagates faster in the coupled model with SST warming. It is shown that this speed-up is due primarily to changes in horizontal moisture advection, with both zonal and meridional advection contributing. The slowing of the MJO zonal circulation per unit precipitation anomaly weakens drying by zonal advection to the east of the MJO precipitation center, causing more rapid MJO propagation in a warmer climate.