Below are images displaying the Climate Prediction Center version of the Wheeler and Hendon (2004) (hereafter WH2004) daily MJO index for both the last 40 and 90 days. The methodology followed at CPC is nearly identical to that outlined in the above reference and operationally displayed at the Australia Bureau of Meteorology Research Centre (BMRC). Slight differences may occur at times due to subtle deviations in input data and methodology and mainly occur during weak MJO periods.

Phase diagrams for the last 40 (top) and 90 days (bottom) illustrating the phase and amplitude of the MJO based on the principal component time series of the leading two EOFs from a combined EOF analysis using 850 hPa zonal wind, 200 hPa zonal wind and OLR. Counter-clockwise movement around the diagram indicates an eastward propagating signal across eight phases from the Indian Ocean to the Pacific and later the western hemisphere. Color of lines distinguish different months and dates are annotated. The farther away from the center of the circle the stronger the MJO signal.

Time series of daily MJO index amplitude from January 2003 to present. Other periods from 1979 to current are available at the links below.