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Systematic Review ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Mar. Sci. | doi: 10.3389/fmars.2019.00582

Observational requirements for long-term monitoring of the global mean sea level and its components over the altimetry era

 Anny Cazenave1, 2, 3*, Ben Hamlington4,  Martin Horwath5, Valentina Barletta6,  Jérôme Benveniste7,  Don Chambers8,  Petra Döll9,  Anna Hogg10, Jean Francois Legeais11, Mark Merrifield12,  Benoit Meyssignac2,  Garry Mitchum8, Steve Nerem13, Roland Pail14, Hindumathi Palanisamy2, Frank Paul15,  Karina von Schuckmann16 and  Philip Thompson17
  • 1Centre National d’Etudes Spatiales (CNES), France
  • 2UMR5566 Laboratoire d'études en géophysique et océanographie spatiales (LEGOS), France
  • 3International Space Science Institute, Switzerland
  • 4NASA Jet Propulsion Laboratory (JPL), United States
  • 5Dresden University of Technology, Germany
  • 6DTU Space - National Space Institute, Denmark
  • 7European Space Research Institute (ESRIN), Italy
  • 8University of South Florida, United States
  • 9Goethe University Frankfurt, Germany
  • 10University of Leeds, United Kingdom
  • 11Collecte Localisation Satellites (CLS), France
  • 12The Scripps Research Institute, United States
  • 13University of Colorado Boulder, United States
  • 14Technical University of Munich, Germany
  • 15University of Zurich, Switzerland
  • 16Mercator Ocean (France), France
  • 17University of Hawaii at Manoa, United States

Present-day global mean sea level evolution results from ocean thermal expansion as well as changes of glaciers and ice sheets mass, and in terrestrial water storage. It is considered as an integrator of changes occurring in the climate system in response to unforced climate variability as well as natural and anthropogenic forcing factors. Monitoring the global mean sea level allows detecting changes (e.g., in trend or acceleration) in one or more components. Closure of the sea level budget implies that the observed sea level changes equal the sum of observed contributions. Mis-closure of these balances indicates errors in some of the components or contributions from missing or un-assessed elements in the budget. Since the launch of TOPEX/Poseidon in 1992, we now have a precise 26-year continuous record of sea level change that has allowed major advances in our understanding of how the Earth is responding to climate change. Two more recent developments fundamentally improved our capability to study the causes of sea level change: the launch of the GRACE satellite gravity mission and the establishment of the Argo network of profiling floats. GRACE has given us the ability to monitor mass redistributions anywhere on Earth, in particular land ice mass variations, and changes in terrestrial water storage and in ocean mass. The Argo network provides a means of monitoring the contribution of thermosteric sea level changes due to the warming of the oceans. Together, satellite altimetry, space gravity, and Argo measurements provide unprecedented insight into the magnitude, spatial variability, and causes of present-day sea level change. With this observational network that has continued to improve in recent years, we are now in a position to address many outstanding questions that are important to planning for future sea level rise. Here, we detail the network for observing sea level and its components, underscore the importance of these observations, and emphasize the need to maintain current systems, improve their sensors, and supplement the observational network where gaps in our knowledge remain.

Keywords: sea ‐ level change, satellite altimetry, GRACE (Gravity recovery and climate experiment), Argo float array, Sea level budget

Received: 29 Oct 2018; Accepted: 02 Sep 2019.

Copyright: © 2019 Cazenave, Hamlington, Horwath, Barletta, Benveniste, Chambers, Döll, Hogg, Legeais, Merrifield, Meyssignac, Mitchum, Nerem, Pail, Palanisamy, Paul, von Schuckmann and Thompson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Anny Cazenave, Centre National d’Etudes Spatiales (CNES), Paris, France, anny.cazenave@legos.obs-mip.fr