The Impact of ENSO on Euro‐Atlantic Circulation a Year Later via Long‐Lived Tropical SST Anomalies

The second winter response to ENSO in the Euro‐Atlantic sector is a surprising recent discovery, however, the underlying mechanisms remain uncertain and are challenging to determine from observations. Here we revisit the second winter response to ENSO using multiple large ensemble climate model simulations to examine its robustness and possible causes. Almost all the models demonstrate a significant second winter response in the Euro‐Atlantic sector, typically resembling positive phases of the North Atlantic Oscillation and/or East Atlantic pattern, but with a large variation across models. The models have strong, long‐lived anomalies in both tropical SSTs and atmospheric angular momentum into the second winter also with variation across models. A maximum covariance analysis approach shows that the preceding tropical SST anomalies explain almost the entire Euro‐Atlantic circulation anomalies. Further analysis reveals that the long‐lived SST anomalies generate substantial tropical precipitation anomalies and associated large‐scale teleconnection patterns in the northern extratropics.