We use the real-time multivariate MJO (RMM) index of Wheeler and Hendon (2004) to define the MJO. This index is comprised of two daily time series, denoted RMM1 and RMM2. These are the principal-component time series of the first two EOFs of combined near-equatorially averaged OLR, and 200 and 850-hPa zonal winds. The indices are available in real time and used to operationally monitor and forecast the state of the MJO. The RMM1 and RMM2 daily time series were extracted for the study period 2003–06, and then aver-aged into 7-day means to be consistent with the Argo and other data used here.