Projected Future Change of MJO and its Extratropical Teleconnection in East Asia during the Northern Winter Simulated in IPCC AR4 Models

Abstract

The future changes in the Madden-Julian Oscillation (MJO) and its extratropical teleconnection in East Asia during the boreal winter are examined by analyzing 12 climate models with good simulation skills of the MJO convective signal in the Coupled Model Intercomparison Project phase 3 (CMIP3). The MJO convection increases over the western to central Indian Ocean (IO) under the warming climate in seven models (MJO-plus models). However, it decreases in the other five models (MJO-minus models). The wintertime sea surface temperature (SST) exhibits more El Niño-like warming in the MJO-plus models. Furthermore, the predicted increase of the MJO amplitude over the IO significantly correlates with that of the amplitude in the El Niño-Southern Oscillation. In East Asia, the convective activity increases (decreases) in the MJO-plus (MJO-minus) models associated with the enhancement (weakening) of the MJO over the western to central IO. The MJO-plus models predict the intensified extratropical circulations as a wave train along the subtropical jet, and increased low-level warm-moist air transport into East Asia related to the intensified Kelvin-Rossby response. Such changes are not detected in the MJO-minus models. It is suggested that proper simulations of the change in the MJO and ENSO are required in order to predict the wintertime climate change in East Asia.