Numerical Simulation of the Atmospheric Response to Equatorial Pacific Sea Surface Temperature Anomalies

Abstract

A number of recent observational and theoretical studies indicate that under certain conditions tropical sea surface temperature anomalies may be capable of producing climatic anomalies at extratropical latitudes. According to the hypothesis put forth in these studies, perturbations in the climatological mean distribution of precipitation in the tropics can influence the extratropical circulation through the action of forced, quasi-stationary, two-dimensional, Rossby wavetrains, which may tend to excite the fastest growing normal mode associated with barotropic instability. Results of previous GCM experiments designed to simulate the atmospheric response to SST anomalies are re-examined in light of this hypothesis and are found to be generally consistent with it. A modeling investigation consisting of three separate GCM experiments was carried out using the GLAS climate model with January initial conditions based on observed data and an equatorial Pacific sea surface temperature anomaly based on ... Abstract A number of recent observational and theoretical studies indicate that under certain conditions tropical sea surface temperature anomalies may be capable of producing climatic anomalies at extratropical latitudes. According to the hypothesis put forth in these studies, perturbations in the climatological mean distribution of precipitation in the tropics can influence the extratropical circulation through the action of forced, quasi-stationary, two-dimensional, Rossby wavetrains, which may tend to excite the fastest growing normal mode associated with barotropic instability. Results of previous GCM experiments designed to simulate the atmospheric response to SST anomalies are re-examined in light of this hypothesis and are found to be generally consistent with it. A modeling investigation consisting of three separate GCM experiments was carried out using the GLAS climate model with January initial conditions based on observed data and an equatorial Pacific sea surface temperature anomaly based on ...