Predictable winter climate in the North Atlantic sector during the 1997-1999 ENSO cycle

The winters of 1997/98 and 1998/99 were marked by strikingly different weather conditions over the North Atlantic ocean and adjacent continents. We use a state-of-the-art atmospheric general circulation model forced with observed sea surface temperatures (SSTs) to investigate the hypothesis that the anomalous conditions in the North Atlantic sector during the winters of 97/98 and 98/99 were related to the ENSO cycle and were therefore potentially predictable. We demonstrate that the major circulation anomalies observed in the North Atlantic sector are reproducible in both winters. We show further that these circulation anomalies were forced primarily by ENSO-related SST anomalies in the Pacific Ocean, but that SST anomalies in the Atlantic Ocean also had an influence. Our results are encouraging for the prospects of useful seasonal predictions for wintertime in the North Atlantic sector.