The mean response of the ecmwf global model to the el niño anomaly in extended range prediction experiments

Abstract

Numerical experiments using a low‐resolution version of the ECMWF general circulation model have been carried out in order to investigate the response of the atmosphere to the “El Niño” sea surface temperature anomaly. The results indicate that in the tropics the response to the anomaly is linear to a first approximation. The observational results of Bjerknes (1966, 1969) that the anomaly intensifies the Hadley circulation and leads to an increase of the subtropical jet are also supported as is the deepening of the Aleutian low. Wave trains and teleconnection patterns in mid‐latitudes as indicated by simplified models could not definitely be identified in the model integrations owing to the high internal variability of the model atmosphere. The usefulness of simple models to simulate the response in mid‐latitudes remains problematic. © 1985 Taylor & Francis Group, LLC.