Numerical Simulations of the Madden-Julian Oscillations During DYNAMO Field Campaign Using the Taiwan CWB Global Model

This study investigates the simulation results of three Madden-Julian Oscillations (MJOs) during the 2011–12 (DYNAMO) Dynamics of the MJO (DYNAMO) field campaign, using the Taiwan Central Weather Bureau (CWB) global model. The Real-time Multivariate MJO (RMM) index with an emphasis on the zonal wind fields is used to examine the model’s skill in predicting global patterns of the MJOs. Eastward propagation of the model simulated precipitation and outgoing longwave radiation (OLR) of three MJO events during the DYNAMO field campaign is also compared with the National Center for Environment Prediction (NCEP) Reanalysis data. In terms of the RMM index, the CWB global model is capable to capture the initiation, development, and weakening of three MJO events around the globe (i.e., the different phases of MJO). On the other hand, the CWB global model has different degrees of agreement of the eastward propagation (in terms of timing, propagation speed, and strength) of convection and precipitation among three MJO scenarios as compared with observations, and the simulation results are highly dependent on the cumulus and air-sea feedback parameterizations used in the model. In a sensitivity simulation with a new Tiedkte cumulus scheme and an air-sea flux scheme, the CWB global model has a better skill in predicting the eastward propagation and intensity of precipitation for three MJO events during the DYNAMO field campaign. Detailed analyses and comparisons of model results of MJO features with available observations during the DYNAMO field experiment will be given at the MJO Symposium.