资源环境科技发展态势分析平台

Reproducing the Madden-Julian Oscillation (MJO) remains a challenge in many climate models. This study compares the MJO simulation skills in 17 pairs of CMIP5 and CMIP6 simulations. Generally, the MJO characteristics are better reproduced in CMIP6, their inter-model spreads are obviously reduced in CMIP6. However, most CMIP6 models still underestimate the frequency of MJO initiation over the Indian Ocean and the MJO amplitude, exaggerate the barrier effect of the Maritime Continent (MC) on MJO propagation. Models with lower MJO simulation skills in their CMIP5 versions show improvements in CMIP6, while other models tend to show degraded MJO simulation skills in CMIP6. The possible reasons for the apparent improvements of MJO simulations from CMIP5 to CMIP6 in six models was further explored. It was found that the enhanced land precipitation over the MC prior to the MJO convection entering this region is more obvious in CMIP6.