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Long‐term polar motion excited by ocean thermal expansion
Author(s) -
Landerer Felix W.,
Jungclaus Johann H.,
Marotzke Jochem
Publication year - 2009
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 - 10.1029/2009gl039692
Subject(s) - polar motion , polar , geology , geophysics , earth's rotation , climatology , environmental science , physics , geodesy , astronomy
Ocean warming is commonly considered unable to excite significant long‐term trends in polar motion. Here, however, we argue that this assumption needs to be revised. We demonstrate that steric sea level rise leads to a distinct pattern of horizontal mass redistribution within ocean basins and hence to ocean bottom pressure changes that alter Earth's inertia tensor on decadal and longer time scales. Based on Earth system model simulations, we estimate that ocean warming leads to polar motion of 0.15 to 0.20 milli‐arcseconds per one millimeter of thermal sea level rise. This is equivalent to a polar motion rate of about 0.47 milli‐arcseconds per year towards 155°W to 160°W for current projections of steric sea level rise during the 21st century. The proposed polar motion signal is therefore not negligible in comparison to other decadal and secular signals, and should be accounted for in the interpretation of polar motion observations.