Relationship between anomalies in sea surface temperature and air-sea heat flux in a simple coupled ocean-atmosphere model

Abstract

Observational studies have shown that sea surface temperature (SST) anomalies are often generated by changes in air-sea heat flux from the atmosphere. By contrast, ocean-only climate models usually assume that SST anomalies are strongly damped by the air-sea heat flux. In this paper we use regression analysis to show that anomalies in air-sea heat flux can systematically drive anomalies in SST even in a very simple coupled ocean-atmosphere model. The atmosphere model is an energy balance model in which atmospheric heat transport is parameterized as a downgradient, diffusive transfer, whereas the ocean model is a three-dimensional circulation model. Anomalies in atmospheric temperature are generated by variability in the ocean model. The region in which the air-sea heat flux anomalies systematically enhance, rather than damp, SST anomalies lies along the periphery of the region of high variance in SST. It exists because the atmosphere model is much more efficient than the ocean model at dispersing heat anomalies from the region of high SST variance, allowing heat anomalies to be partially reabsorbed by the ocean, where the SST variance is less. The regression analysis also shows that the damping time for SST anomalies in other parts of the model domain is typically several hundred days. Copyright 1997 by the American Geophysical Union.