Temperature anomalies (C) in the North Pacific Ocean averaged between 170W-145W are displayed as a function of latitude and depth (m). The temperature anomalies are averaged over four year periods and shown for 5 consecutive periods starting in 1970-73.

The first panel indicates a warm temperature anomaly in the surface layer at about 38N for the period 1970-73. The anomaly moves down and southward over the next two periods reaching 21N and 300 m in depth by the early 80's. During the period 1978-81 cold surface waters form at ~33N and like the previous warm anomaly moves down and south with time. This is one of the first observational studies to show the evolution of subsurface ocean temperature anomalies. In addition, the temperature anomalies travel along isopychnal surfaces (lines of constant density) and at speeds consistent with the estimated wind-driven circulation, supporting recent theories of how water enters and flows within the permanent thermocline.