The Effect of Moisture in Different Altitude Layers on the Eastward Propagation of MJO  

作　　者：Xiaoyu ZHU Zhong ZHONG Yimin ZHU Yunying LI Yijia HU Yao HA 

机构地区：[1]College of Meteorology and Oceanography,National University of Defense Technology,Changsha,410000,China [2]Key Laboratory for Virtual Geographic Environment,School of Geography Science,Nanjing Normal University,Nanjing,210023,China [3]Jiangsu Collaborative Innovation Center for Climate Change,School of Atmospheric Sciences,Nanjing University,Nanjing,210000,China

出　　处：《Journal of Meteorological Research》2024年第3期437-452,共16页气象学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(41975090 and 42075077);Natural Science Foundation of Hunan Province,China(2022JJ20043).

摘　　要：In this study,driven by ERA5 reanalysis data,the Weather Research and Forecasting(WRF)version 4.0 was used to investigate the eastward propagation of the Madden-Julian oscillation(MJO)in the tropical atmosphere during December-February(DJF)of 2007/2008.The experiment with 11 cumulus parameterization schemes respectively shows that the Grell 3D scheme is one of several worse ones in describing MJO activities.In addition,still by use of the Grell 3D scheme,four nudging assimilation experiments for water vapor in all model vertical layers(Ndg_all),lower layers(Ndg_low),middle layers(Ndg_mid),and upper layers(Ndg_upp)were conducted.It is found that when the water vapor in the model approaches to the observed value,the model performance for MJO activities is improved greatly.Among the four nudging simulations,Ndg_all certainly performs best.Although Ndg_mid is important for the MJO-filtered profiles related to moisture,Ndg_low and Ndg_upp exhibit superiority to Ndg_mid in simulating MJO eastward propagation.Ndg_low has advantages when MJO features are represented by zonal wind at 850 hPa and precipitation because the lower-level MJO-filtered moisture is conducive to the existence of lower-level condensational heating to the east of the MJO convective center.Ndg_upp performs better when describing the MJO eastward propagation features by outgoing longwave radiation(OLR)since it can capture the moisture and cloud top temperature of deep convection associated with MJO,as well as front Walker cell.These results suggest that the lower-level moisture is more important in regulating the MJO eastward propagation,and the observed maximum MJO-filtered moisture in the middle troposphere might be a phenomenon accompanying the MJO deep convection,but not a factor controlling its eastward propagation.

关 键 词：Madden-Julian oscillation(MJO) nudging technique Weather Research and Forecasting(WRF)model vertical moisture structure 

分 类 号：P426[天文地球—大气科学及气象学]