A stratospheric "drain" over the maritime continent

Operational wind data are used to show that the time-averaged mass flux near the tropopause is downward over the maritime continent (Indonesia) region during both summer and winter. The air descends within a layer above the convective level of neutral buoyancy (despite mean upward motion below and above this layer) and must rise through the mean tropopause elsewhere, contradicting the common view that the entry occurs over strongly-convecting regions. Closing the energy budget in the sinking regions requires an energy sink; one possibility is that overshooting convective clouds are irreversibly injecting cold, heavy air at great heights.