EASTWARD PROPAGATING SIMILAR-TO-2-DAY TO 15-DAY EQUATORIAL CONVECTIONAND ITS RELATION TO THE TROPICAL INTRASEASONAL OSCILLATION

Anomalies of outgoing longwave radiation (OLR) in 1980-1989 were exami ned in a narrow latitude band about the equator to elucidate the propa gation and interaction of tropical intraseasonal oscillations (TIOs) a nd synoptic-scale convective activity. Hovmoller diagrams of OLR data reconstructed from two frequency bands (corresponding to periods of si milar to 30-60 days and similar to 2-15 days, respectively) revealed a clear distinction between the phase speed of eastward moving TIOs (3- 7 m s(-1)) and that of eastward synoptic-scale convection (10-13 m s(- 1)). Coherent propagation of TIOs from the Indian to the western Pacif ic Oceans was often observed with temporary diminution of amplitude ov er the maritime continent. Propagation of high-frequency anomalies was generally confined to an individual basin. Dominance of eastward prop agating synoptic-scale convection in the equatorial zone contrasts sha rply with the westward propagation of off-equatorial convergence zones . Interaction between the TIO and high-frequency activity resolved by daily OLR was visible as a modest enhancement of eastward synoptic-sca le events (and of high-frequency activity in general) during the conve ctively active phase of the TIO.