A Study of SST Warming Trend in the Western Equatorial Pacific in a Coupled Ocean-Atmosphere-Land GCM

In a version of LASG coupled ocean-atmosphere-land system model, where a diurnal cycle of solar radiation is included, a rapid SST warming trend of about 2.0oC appears in the western equatorial Pacific within the first two years of an integration. An analysis reveals that the appearance of the surface westerly wind anomaly since the fifth month of the integration is responsible for the SST warming. To reduce the SST warming, the reference heat flux used in the model is then redefined according to the first 4 months, instead of the first 3 years, of a trial run. It is found that the refining of the reference heat flux is successful in avoiding the unrealistic persistent westerly wind anomaly. Consequently, the SST warming is almost com-pletely removed. It is explored that the persistent westerly wind anomaly is induced by the anomalous sur-face pressure patterns in the northern tropical and subtropical regions, which is related to the errors in the surface heat flux in the off-equatorial regions.