- DYNAMO and TOGA-COARE observations and reanalysis-based surface flux products are
used to test theories of atmosphere-ocean interaction that explain the Madden-Julian
Oscillation (MJO). Negative intraseasonal outgoing longwave radiation, indicating deep
convective clouds, is in phase with increased surface wind stress, decreased solar heating,
and increased surface turbulent heat flux—mostly evaporation—from the ocean to the
atmosphere. Net heat flux cools the upper ocean in the convective phase. Sea surface
temperature (SST) warms during the suppressed phase, reaching a maximum before the onset
of MJO convection. The timing of convection, surface flux, and SST is consistent from the
central Indian Ocean (70°E) to the western Pacific Ocean (160°E).
Mean surface evaporation observed in TOGA COARE and DYNAMO (110 W m⁻²) accounts
for about half of the moisture supply for the mean precipitation (210 W m⁻² for DYNAMO).
Precipitation maxima are an order of magnitude larger than evaporation anomalies, requiring
moisture convergence in the mean, and on intraseasonal and daily time scales. Column
integrated moisture increases 2 cm before the convectively active phase over the research
vessel Revelle in DYNAMO, in accord with MJO moisture recharge theory. Local surface
evaporation does not significantly recharge the column water budget before convection. As
suggested in moisture mode theories, evaporation increases the moist static energy of the
column during convection. Rather than simply discharging moisture from the column, the
strongest daily precipitation anomalies in the convectively active phase accompany
increasing column moisture.