The Response of Tropical Climate to the Equatorial Emergence of Spiciness Anomalies*

Abstract

Abstract The ocean–atmosphere response to the surfacing of temperature anomalies from the oceanic thermocline is a key process in climate variability with decadal time scales. Using a coupled general circulation model, it is shown how density-compensating temperature and salinity (spiciness) anomalies emerging in the upwelling region of the equatorial Pacific modulate tropical climate. Upon reaching the surface in the central equatorial Pacific, warm and salty spiciness anomalies increase sea surface temperature and salinity, and vent their heat anomaly to the atmosphere, primarily by the latent heat flux. The associated surface buoyancy flux increases vertical mixing, and thereby dampens surface temperature anomalies. The moisture added to the atmosphere increases precipitation in the western Pacific and intertropical convergence zone, and strengthens the trade winds east, and weakens them west of the date line. Central equatorial Pacific surface temperatures are slightly warmed by the resulting deepened...