Cold water intrusion in the eastern Gulf of Alaska in 2002

A patch of anomalously cold and fresh oceanic water appeared off the west coast of North America during the summer of 2002. The coldest anomaly resided 100 to 150 m below the surface, and was the coldest anomaly ever measured in summer. The motion of this water mass is tracked through the Gulf of Alaska in early 2002 and into the following year. It may have formed near the centre of the Alaskan Gyre during previous winters and advected eastward onto the continental margin. Examination of summer temperature anomalies at this range of depths in the south-east Gulf of Alaska over the previous 35 years shows that the anomalies responded to interannual wind anomalies attributed to the El Nino Southern Oscillation (ENSO), and the Pacific Decadal Oscillation (PDO). Gulf of Alaska temperatures lag these signals, offering hope that future temperature changes will be predicted.