Steric Sea-Level Change and its Impact on the Gravity Field caused by Global Climate Change |
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Authors: | Sabine Roedelsperger Michael Kuhn Oleg Makarynskyy Carl Gerstenecker |
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Institution: | (1) Institute of Physical Geodesy, Darmstadt University of Technology, Petersenstrasse 13, 64287 Darmstadt, Germany;(2) Western Australian Centre for Geodesy and The Institute for Geoscience Research, Curtin University of Technology, GPO Box U1987, Perth, WA, 6845, Australia;(3) Present address: Asia-Pacific Applied Science Associates, PO Box 7650, Cloisters Square, Perth, WA, 6850, Australia |
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Abstract: | It is sometimes assumed that steric sea-level variations do not produce a gravity signal as no net mass change, thus no change
of ocean bottom pressure is associated with it. Analyzing the output of two CO2 emission scenarios over a period of 2000 years in terms of steric sea-level changes, we try to quantify the gravitational
effect of steric sea-level variations. The first scenario, computed with version 2.6 of the Earth System Climate Model developed
at the University of Victoria, Canada (UVic ESCM), is implemented with a linear CO2 increase of 1% of the initial concentration of 365 ppm and shows a globally averaged steric effect of 5.2 m after 2000 years.
In the second scenario, computed with UVic ESCM version 2.7, the CO2 concentration increases quasi-exponentially to a level of 3011 ppm and is hold fixed afterwards. The corresponding globally
averaged steric effect in the first 2000 years is 2.3 m. We show, due to the (vertical) redistribution of ocean water masses
(expansion or contraction), the steric effect results also in a small change in the Earth’s gravity field compared to usually
larger changes associated with net mass changes. Maximum effects for computation points located on the initial ocean surface
can be found in scenario 1, with the effect on gravitational attraction and potential ranging from 0.0 to −0.7·10−5 m s−2 and −3·10−3 to 6·10−3 m2 s−2, respectively. As expected, the effect is not zero but negligible for practical applications. |
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Keywords: | Global warming climate model sea level change steric effect gravity field change |
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