| Assimilation of outgoing long-wave radiation derived rain rates using physical initialization is incorporated into the Florida State University coupled ocean-atmosphere global general circulation model. Seasonal predictions of the 1986–1989 El Niño-Southern Oscillation event starting from initial states generated by the coupled physical initialization scheme are compared to predictions based on a coupled Newtonian relaxation scheme.; The initializations are performed for 6-month periods beginning on December 1, 1986 and 1987 as well as June 1, 1987 and 1988, generating four initial states for the summer and winter seasons. A 7-member ensemble simulation (based on nearby coupled initial states) is conducted for each initialization experiment. The winter (December through February) and summer (June through September) simulations are evaluated to determine the impact of physical initialization. The physical initialization properly locates the imposed convection and generates a circulation consistent with the convective heating. The Newtonian relaxation method generates stronger subsurface temperature anomalies during initialization in the El Nino seasons compared to those of physical initialization. Simulations with physical initialization generate better SSTs in the Nino-4 region of the Pacific. Physical initialization strongly impacts the large-scale extratropical Pacific/North American (PNA) pattern compared to the Newtonian approach, generating temperature, circulation, and precipitation anomalies close to observations. These results indicate that a scheme such as physical initialization might be useful for coupled initialization (or a non-coupled study) in order to properly represent the extratropical anomalies. |
