Dynamics of the South American coastal desert

The world's driest coastal desert is in South America along the coasts of Peru and Chile. The desert's maintenance is investigated by studying the local dynamics of the low-level southerly flow along the coast. A linear boundary-layer model is used in which a Boussinesq atmosphere is driven by a surface thermal contrast on a β plane. The effect of nonuniform rotation is responsible for the presence of subsidence along the coast and inland. The costal subsidence helps maintain the desert by increasing the static stability and suppressing deep convection. The predicted vertical wind profiles agree well with the observations for Lima, Peru. Sensitivity tests indicate that the flow depends on the interplay between stratification, friction, and the Coriolis parameter and its variation (β). The mechanical frictional effects are mainly constrained to a shallow Ekman layer, whereas the thermal effects are manifested in deeper layers controlled by the β effect. -from Authors