Evaluation of Budget Analyses during MISMO

Abstract

Abstract Results of sounding-derived heat and moisture budgets for the Mirai Indian Ocean Cruise for the Study of the MJO Onset (MISMO) project in 2006 are evaluated using observational and simulated datasets. Estimated rainfall rates from the budget analyses agree well with both the satellite-derived products and in situ rain gauge measurements in the period leading up to the convectively active phase of the MJO. During the active phase, however, large discrepancies are found in the temporal variation of the rainfall estimates on the time scale of a few to several days. Utilizing MJO circulations simulated by the two numerical models, a linear model and a high-resolution AGCM, it is revealed that this discrepancy may result from inability of the MISMO triangular network to properly capture the divergence associated with the Rossby and/or inertia–gravity wave components of the circulation. A rectangular array is demonstrated to be superior at capturing the wind associated with these wave disturbances. Possible effects of the equatorial waves and sampling issues, which could act to enhance or suppress the error in the present case, are discussed. The reliability of the budget analyses during the preactive period is also supported by both model simulations.