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Proc Natl Acad Sci U S A. 2016 Feb 9;113(6):1504-9. doi: 10.1073/pnas.1519132113. Epub 2016 Jan 25.

Revisiting the contemporary sea-level budget on global and regional scales.

Author information

1
Institute of Geodesy and Geoinformation, University of Bonn, D-53115 Bonn, Germany; roelof@geod.uni-bonn.de.
2
Institute of Geodesy and Geoinformation, University of Bonn, D-53115 Bonn, Germany; Alfred Wegener Institute for Polar and Marine Research, D-27570 Bremerhaven, Germany;
3
Institute of Geodesy and Geoinformation, University of Bonn, D-53115 Bonn, Germany;
4
Alfred Wegener Institute for Polar and Marine Research, D-27570 Bremerhaven, Germany;
5
GFZ German Research Centre for Geosciences, D-14473 Potsdam, Germany.

Abstract

Dividing the sea-level budget into contributions from ice sheets and glaciers, the water cycle, steric expansion, and crustal movement is challenging, especially on regional scales. Here, Gravity Recovery And Climate Experiment (GRACE) gravity observations and sea-level anomalies from altimetry are used in a joint inversion, ensuring a consistent decomposition of the global and regional sea-level rise budget. Over the years 2002-2014, we find a global mean steric trend of 1.38 ± 0.16 mm/y, compared with a total trend of 2.74 ± 0.58 mm/y. This is significantly larger than steric trends derived from in situ temperature/salinity profiles and models which range from 0.66 ± 0.2 to 0.94 ± 0.1 mm/y. Mass contributions from ice sheets and glaciers (1.37 ± 0.09 mm/y, accelerating with 0.03 ± 0.02 mm/y(2)) are offset by a negative hydrological component (-0.29 ± 0.26 mm/y). The combined mass rate (1.08 ± 0.3 mm/y) is smaller than previous GRACE estimates (up to 2 mm/y), but it is consistent with the sum of individual contributions (ice sheets, glaciers, and hydrology) found in literature. The altimetric sea-level budget is closed by coestimating a remaining component of 0.22 ± 0.26 mm/y. Well above average sea-level rise is found regionally near the Philippines (14.7 ± 4.39 mm/y) and Indonesia (8.3 ± 4.7 mm/y) which is dominated by steric components (11.2 ± 3.58 mm/y and 6.4 ± 3.18 mm/y, respectively). In contrast, in the central and Eastern part of the Pacific, negative steric trends (down to -2.8 ± 1.53 mm/y) are detected. Significant regional components are found, up to 5.3 ± 2.6 mm/y in the northwest Atlantic, which are likely due to ocean bottom pressure variations.

KEYWORDS:

GRACE; altimetry; budget; sea level; steric

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