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On the Pacific Ocean regime shift
Author(s) -
Stephens Cathy,
Levitus Sydney,
Antonov John,
Boyer Timothy P.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl012813
Subject(s) - anomaly (physics) , ocean heat content , climatology , regime shift , sea surface temperature , pacific ocean , pacific decadal oscillation , geology , oceanography , environmental science , structural basin , physics , ecology , paleontology , condensed matter physics , ecosystem , biology
The temporal variability of Pacific Ocean upper ocean heat content is examined for the 1948–1998 period using gridded, objectively analyzed temperature anomaly fields. Results indicate a “regime shift” in upper ocean temperature structure occurred in conjunction with the atmospheric shift in sea level pressure around 1975 leading to warming (cooling) in the eastern (western) equatorial Pacific. The shift is a basin‐wide phenomenon affecting the thermal structure from 60°S to 70°N. EOF analysis of the Pacific Ocean heat content (0–125 m) shows a shift from a relatively cool to a warm state in the equatorial Pacific during the mid‐1970s. Further analysis of the gridded temperature anomaly fields shows equatorial warming to be as much as 1.5°C and a cooling in the North Pacific of 1°C, down to 250 meters, after the mid‐1970s. Overall, the analysis indicates the “regime shift” continues through 1998 with no signs of returning to a cooler phase.