Indices of intraseasonal and interannual Indian Ocean convection were created by filtering area averaged outgoing longwave radiation for a low-pass filter of greater than 105 days and a band-pass filter of 33-105 days, respectively, over the region 80E-110E and 15S-5N, and are in good agreement with a monthly EOF analysis. Interannual Indian Ocean convective variability is related to a convection seesaw between the Maritime Continent and West Pacific Ocean, and is similar to the observed ENSO convection response. The similarly between the ENSO and interannual Indian Ocean convection responses improves when the SST gradient over the region 5S to 5N and 140E to 150E is strong, suggesting that the West Pacific SST gradient is a link between atmospheric convection over the Pacific and Indian Oceans. Barotropic ray tracing shows a stationary barotropic Rossby wave propagation mechanism through the North Pacific, North America, Atlantic, North Africa and Middle East into Asia originating over the Indian Ocean. Comparison of intraseasonal and interannual variability suggests that a convectively active (inactive) Indian Ocean on intraseasonal time scales corresponds to a convectively inactive (active) Indian Ocean on interannual time scales. However, intraseasonal convective activity appears to be a stronger indicator of interannual convective activity than the reverse.
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