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Monitoring Modes of Coherent Tropical Convective Variability:

Real-time filtering of OLR data to obtain the Madden-Julian oscillation and various convectively coupled equatorial waves, based on the "climatological" spectral peaks of a long record of satellite-observed data.


Antisymmetric Modes   Symmetric Modes
Click to enlarge and for more information   Click to enlarge and for more information
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Fig 1. Regions of wavenumber-frequency filtering for the outgoing longwave radiation (OLR) signals of certain modes of coherent tropical variability. These modes are identified as spectral peaks (the shading) in a wavenumber-frequency spectrum analysis of a long record of satellite-observed OLR, a good proxy for deep tropical convection. Filtering is for the Madden-Julian Oscillation (MJO; blue), Kelvin wave (green), n = 1 equatorial Rossby (ER) wave (black), and mixed Rossby-gravity (MRG) wave (brown). The so-called "convectively coupled equatorial waves" are defined to be in either the antisymmetric or symmetric components only, while the MJO is allowed to contain both components. For details, see Wheeler and Kiladis (1999, Journal of the Atmospheric Sciences; download pdf file).

The real-time filtering technique, its validation and skill are described in a paper available here (pdf file).