A tropical and subtropical land-sea-atmosphere drought oscillation mechanism

A two-column atmospheric model on a land-sea interface is studied. The model has sophisticated convection, cloud, and radiation schemes, a mixed layer ocean, and a bucket model to simulate land hydrology. A self-sustained oscillation in soil moisture with a period on the order of months is found. This oscillation is strongest when the model is run with parameters chosen to correspond to the and subtropics. The effect of changing model parameters on the oscillation is explored. The existence and qualitative behavior of the oscillation are relatively robust to changes in model parameters.