Air-sea interaction over the Maritime Continent and the TBO

The tropospheric biennial oscillation (TBO) is identified by means of empirical orthogonal function analysis of global sea surface temperatures and available station rainfall data for the 30 year period 1951-80. Counter to previous studies which have indicated a prominent role for the Asian monsoon, the seat of the TBO is found to be over the Maritime Continent and the surronding oceans to the southwest. The main driver of the TBO is hypothesized to be air-sea interaction over the Martime Continent that is remotely forced by anomalous SST in the eastern Pacific associated with ENSO. In response to this remote forcing, local SST grows during April-October and rapidly decays during November-February. Concomitant rainfall anomalies develop over the Martime Continent in association with the local SST variations.

A simple is developed which presumes that SST over the Maritime Continent is remotely forced by eastern Pacific SST anomalies. The eastern Pacific anomalies are modeled as red noise which drive the aforementioned seasonally varying feedback processes across the Maritime Continent. This model realistically captures much of the observed behavior of the TBO, including its phase locking to the annual cycle and its episodic nature.