We
examine long tide gauge records in every ocean basin to examine whether a quasi
60-year oscillation observed in global mean sea level (GMSL) reconstructions
reflects a true global oscillation, or an artifact associated with a small
number of gauges.
We find
that there is a significant oscillation with a period around 60-years in the
majority of the tide gauges examined during the 20th Century, and that it
appears in every ocean basin.
Averaging
of tide gauges over regions shows that the phase and amplitude of the
fluctuations are similar in the North Atlantic, western North Pacific, and
Indian Oceans, while the signal is shifted by 10 years in the western South
Pacific. The only sampled region with no apparent 60-year fluctuation is the
Central/Eastern North Pacific.
The
phase of the 60-year oscillation found in the tide gauge records is such that
sea level in the North Atlantic, western North Pacific, Indian Ocean, and
western South Pacific has been increasing since 1985–1990.
Although
the tide gauge data are still too limited, both in time and space, to determine
conclusively that there is a 60-year oscillation in GMSL, the possibility
should be considered when attempting to interpret the acceleration in the rate
of global and regional mean sea level rise.
Don P. Chambers, College
of Marine Science, University of South Florida, St. Petersburg, Florida, USA
Mark A. Merrifield,
Department of Oceanography, University of Hawai’i at Mānoa, Honolulu, Hawaii,
USA
R. Steven Nerem, CIRES,
University of Colorado Boulder, Boulder, Colorado, USA
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