The effects of air-sea coupling over the tropical Indian Ocean（TIO） on the eastward propagating boreal winter intraseasonal oscillation（MJO） are investigated by comparing a fully coupled and a partially decoupled ...The effects of air-sea coupling over the tropical Indian Ocean（TIO） on the eastward propagating boreal winter intraseasonal oscillation（MJO） are investigated by comparing a fully coupled and a partially decoupled Indian Ocean experiment using the SINTEX-F coupled model.Air-sea coupling over the TIO significantly enhances the intensity of the eastward propagations of the MJO along the5°-10°S zonal areas.The zonal asymmetry of the SST anomaly（SSTA） is responsible for the enhanced eastward propagation.A positive SSTA appears to the east of the MJO convection,which results in the boundary layer moisture convergence and positively feeds back to the MJO convection.In addition,the air-sea interaction effect on the eastward propagation of the MJO is related to the interannual variations of the TIO.Air-sea coupling enhances（reduces） the eastward-propagating spectrum during the negative Indian Ocean dipole mode and positive Indian Ocean basin mode.Such phase dependence is attributed to the role of the background mean westerly in affecting the wind-evaporation-SST feedback.Air-sea coupling（decoupling） enhances（reduces） the zonal asymmetry of the low-level specific humidity,and thus the eastward propagation spectrum of the MJO.展开更多
基金supported by the National Basic Research Program of China[grant number 2014CB953901],support from the National Basic Research Program of China[grant number 2015CB453200]the National Natural Science Foundation of China[grant numbers 41675096,41575043,41375095,and 41505067],the National Natural Science Foundation of China[grant numbers 41475084 and 41630423]
文摘The effects of air-sea coupling over the tropical Indian Ocean（TIO） on the eastward propagating boreal winter intraseasonal oscillation（MJO） are investigated by comparing a fully coupled and a partially decoupled Indian Ocean experiment using the SINTEX-F coupled model.Air-sea coupling over the TIO significantly enhances the intensity of the eastward propagations of the MJO along the5°-10°S zonal areas.The zonal asymmetry of the SST anomaly（SSTA） is responsible for the enhanced eastward propagation.A positive SSTA appears to the east of the MJO convection,which results in the boundary layer moisture convergence and positively feeds back to the MJO convection.In addition,the air-sea interaction effect on the eastward propagation of the MJO is related to the interannual variations of the TIO.Air-sea coupling enhances（reduces） the eastward-propagating spectrum during the negative Indian Ocean dipole mode and positive Indian Ocean basin mode.Such phase dependence is attributed to the role of the background mean westerly in affecting the wind-evaporation-SST feedback.Air-sea coupling（decoupling） enhances（reduces） the zonal asymmetry of the low-level specific humidity,and thus the eastward propagation spectrum of the MJO.
