Map sequence for the most recent 40 days of the OLR anomalies filtered for the various wavenumber-frequency domains defined in Fig. 1a or 1b. The first panel corresponds to the defined filtering for the Madden-Julian oscillation (MJO). The second panel corresponds to the defined filtering for the n = 1 equatorial Rossby (ER) wave. The third panel correpsonds to the defined filtering for the Kelvin wave, and the fourth panel corresponds to the defined filtering for the mixed Rossby-gravity (MRG) wave. Note the restriction of the n = 1 ER and Kelvin waves to be symmetric about the equator in OLR, while the MRG wave is antisymmetric, and the MJO is allowed to contain both symmetric and antisymmetric components. One pass of a 1-2-1 filter has been applied in the meridional direction to each of the maps for the purpose of smoothing.