Altimetry for the future: Building on 25 years of progress

International Altimetry Team

Research output: Contribution to journalArticlepeer-review

109 Scopus citations


In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion.

Original languageEnglish (US)
Pages (from-to)319-363
Number of pages45
JournalAdvances in Space Research
Issue number2
StatePublished - Jul 15 2021

Bibliographical note

Funding Information:
This collective synthesis of the worldwide interdisciplinary altimetry community would not have been possible without the support that has been given to each of the contributors by numerous institutions at local, national and intergovernmental levels. At the forefront of this support, we must obviously mention the space agencies CNES, ESA and NASA which have played and still play a decisive role in the development and launch of several prominent altimetry missions from the outset. Other agencies such as DLR, EUMETSAT, ISRO, NOAA, NSOAS and organizations such as CMEMS, also contribute significantly to developments in all forms of altimetry. We are very grateful to all the players in the previous organizations and many others that we cannot list extensively here, and that were all behind this remarkable success of radar altimetric technology and made the many scientific, technical and application developments possible. Sincere thanks should be specifically addressed to all contributors either individually or as responsible in various capacities (thematic leaders, session chairmen, contributors to round tables, actors from different space agencies or national organizations or international, etc.), who provided their inputs in different forms to this document. We also warmly thank the reviewers for their helpful comments to improve the article. The views, opinions, and findings contained in this article are those of the authors and should not be construed as an official National Oceanic and Atmospheric Administration (NOAA) or U.S. Government position, policy, or decision. This also applied to other Organizations or Institutes.

Publisher Copyright:
© 2021 COSPAR


  • Coastal oceanography
  • Cryospheric sciences
  • Hydrology
  • Oceanography
  • Satellite altimetry
  • Sea level

ASJC Scopus subject areas

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences(all)


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