Tropical oceanic rainfall and sea surface temperature structure: Parsing causation from correlation in the MJO

Analyses include the tropical Indian Ocean, Maritime Continent, and tropical western Pacific regions. The authors examine the anomalies of and correlations between SST structure, the frequency of rainfall events, and rainfall amount.

Based on detailed examination of a 49-month time series, all findings are statistical inferences and interpretations consistent with established theory. The statistical inferences are broadly consistent with a pivotal role played by the convergent Laplacian of SST together with an expected, but somewhat indirect, role of SST itself. The main role of SST in the MJO passband appears limited to production of moist static energy, which is highly correlated with cumulative precipitation, yet bears a decidedly conditional relationship to the occurrence of rainfall.