A CRITIQUE OF WAVE-CISK AS AN EXPLANATION FOR THE 40-50 DAY TROPICAL INTRASEASONAL OSCILLATION

The two major difficulties, i.e., the excessive speed and the smallest preferred scale, encountered by wave-CISK as an explanation for the 4 0-50 day tropical intraseasonal oscillation (or the Madden-Julian osci llation, MJO), as demonstrated in many studies, are examined. In addit ion, wave-CISK is contrasted with a more promising framework for inter preting MJO recently proposed by Chao and Lin. The central cause for t he two difficulties can be attributed to the convective heating formul ation used. Also, depending on how one defines it, the wave-CISK conce pt as the foundation for interpreting MJO is at best inadequate and at worst erroneous.