A theory for the tropical tropospheric biennial oscillation

Abstract

The key questions of how the tropospheric biennial oscillation (TBO) maintains the same phase from northern summer in South Asia to southern summer in Australia, and how the reversed phase can last through three locally inactive seasons to the next monsoon, are studied by a simple tropical atmosphere-ocean-land model. The model has five boxes representing the South Asian and Australian monsoon regions and the equatorial Indian and western and eastern Pacific Oceans. The five regions interact with each other through the sea surface temperature (SST)-monsoon, evaporation-wind, monsoon-Walker circulation, and wind stress-ocean thermocline feedbacks.