The workings of the Empirical Wave Propagation for MJO prediction are explained in
Full reference:
Huug van den Dool and Suranjana Saha, 2004: Analysis of Propagating Modes in the Tropics in Short AMIP runs.
Proceedings of the WCRP/WGNE Workshop on the Second Phase of the Atmospheric Model Intercomparison Project (AMIP2), Meteo-France, Toulouse, France 11.14 November, 2002, p87-91. (Edited by P. Gleckler August 16, 2004, UCRL-PROC-209115)
Huug.