28 Apr 2021

28 Apr 2021

Review status: this preprint is currently under review for the journal ESSD.

Global sea-level budget and ocean-mass budget, with focus on advanced data products and uncertainty characterisation

Martin Horwath1, Benjamin D. Gutknecht1, Anny Cazenave2,3, Hindumathi Kulaiappan Palanisamy2,4, Florence Marti2, Ben Marzeion5, Frank Paul6, Raymond Le Bris6, Anna E. Hogg7, Inès Otosaka8, Andrew Shepherd8, Petra Döll9,10, Denise Cáceres9, Hannes Müller Schmied9,10, Johnny A. Johannessen11, Jan Even Øie Nilsen11,12, Roshin P. Raj11, René Forsberg13, Louise Sandberg Sørensen13, Valentina R. Barletta13, Sebastian B. Simonsen13, Per Knudsen13, Ole Baltazar Andersen13, Heidi Randall13, Stine K. Rose13, Christopher J. Merchant14, Claire R. Macintosh14, Karina von Schuckmann15, Kristin Novotny2, Andreas Groh2, Marco Restano16, and Jérôme Benveniste17 Martin Horwath et al.
  • 1Technische Universität Dresden, Institut für Planetare Geodäsie, Dresden, D
  • 2LEGOS Toulouse, F
  • 3International Space Science Institute, Bern, Switzerland
  • 4Centre for Climate Research Singapore, Meteorological Service Singapore, Singapore
  • 5Institut of Geography and MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
  • 6University of Zurich, CH
  • 7University of Leeds, UK
  • 8Centre for Polar Observation and Modelling, University of Leeds, UK
  • 9Institute of Physical Geography, Goethe University Frankfurt, Frankfurt am Main, D
  • 10Senckenberg Leibniz Biodiversity and Climate Research Centre (SBiK-F), Frankfurt am Main, D
  • 11Nansen Environmental and Remote Sensing Center, Bergen, NO
  • 12Institute of Marine Research, Bergen, NO
  • 13Technical University of Denmark, DK
  • 14University of Reading and National Centre for Earth Observation, UK
  • 15Mercator Ocean International, Toulouse, F
  • 16Serco/ESRIN, I
  • 17ESA ESRIN, I

Abstract. Studies of the global sea-level budget (SLB) and the global ocean-mass budget (OMB) are essential to assess the reliability of our knowledge of sea-level change and its contributions. Here we present datasets for times series of the SLB and OMB elements developed in the framework of ESA's Climate Change Initiative. We use these datasets to assess the SLB and the OMB simultaneously, utilising a consistent framework of uncertainty characterisation. The time series, given at monthly sampling, include global mean sea-level (GMSL) anomalies from satellite altimetry; the global mean steric component from Argo drifter data with incorporation of sea surface temperature data; the ocean mass component from Gravity Recovery and Climate Experiment (GRACE) satellite gravimetry; the contribution from global glacier mass changes assessed by a global glacier model; the contribution from Greenland Ice Sheet and Antarctic Ice Sheet mass changes, assessed from satellite radar altimetry and from GRACE; and the contribution from land water storage anomalies assessed by the WaterGAP global hydrological model. Over the period Jan 1993–Dec 2016 (P1, covered by the satellite altimetry records), the mean rate (linear trend) of GMSL is 3.05 ± 0.24 mm yr−1. The steric component is 1.15 ± 0.12 mm yr−1 (38 % of the GMSL trend) and the mass component is 1.75 ± 0.12 mm yr−1 (57 %). The mass component includes 0.64 ± 0.03 mm yr−1 (21 % of the GMSL trend) from glaciers outside Greenland and Antarctica, 0.60 ± 0.04 mm yr−1 (20 %) from Greenland, 0.19 ± 0.04 mm yr−1 (6 %) from Antarctica, and 0.32 ± 0.10 mm yr−1 (10 %) from changes of land water storage. In the period Jan 2003–Aug 2016 (P2, covered by GRACE and the Argo drifter system), GMSL rise is higher than in P1 at 3.64 ± 0.26 mm yr−1. This is due to an increase of the mass contributions (now about 2.22 ± 0.15 mm yr−1, 61 % of the GMSL trend), with the largest increase contributed from Greenland. The SLB of linear trends is closed for P1 and P2, that is, the GMSL trend agrees with the sum of the steric and mass components within their combined uncertainties. The OMB budget, which can be evaluated only for P2, is also closed, that is, the GRACE-based ocean-mass trend agrees with the sum of assessed mass contributions within uncertainties. Combined uncertainties (1-sigma) of the elements involved in the budgets are between 0.26 and 0.40 mm yr−1, about 10 % of GMSL rise. Interannual variations that overlie the long-term trends are coherently represented by the elements of the SLB and the OMB. Even at the level of monthly anomalies the budgets are closed within uncertainties, while also indicating possible origins of remaining misclosures.

Martin Horwath et al.

Status: open (until 23 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on essd-2021-137', J.F. Legeais, 04 May 2021 reply

Martin Horwath et al.

Data sets

ESA Sea Level Budget Closure Climate Change Initiative (SLBC_cci): Time series of global mean sea level budget and ocean mass budget elements (1993-2016, at monthly resolution), version 2.1 Horwath, M. et al.

Martin Horwath et al.


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Short summary
Global mean sea level change observed from 1993 to 2016 (at a mean rate of 3.05 mm per year) matches the combined effect of changes in water density (thermal expansion) and ocean mass. Ocean mass change is assessed through the contributions from glaciers, ice sheets and land water storage or directly from satellite data since 2003. Our budget assessments of linear trends and monthly anomalies utilise new datasets and uncertainty characterisations developed within ESA's Climate Change Initiative.