Altimetry for the future: Building on 25 years of progress
Saleh Abdalla, Abdolnabi Abdeh Kolahchi, Michäel Ablain, Susheel Adusumilli, Suchandra Aich Bhowmick, Eva Alou‐Font, L. Amarouche, Ole Andersen, Helena Antich, Lotfi Aouf, Brian K. Arbic, Thomas Armitage, Sabine Arnault, Camila Artana, Giuseppe Aulicino, Nadia Ayoub, Sergei Badulin, Steven G. Baker, Chris Banks, Lifeng Bao, Silvia Barbetta, Bàrbara Barceló‐Llull, François Barlier, Sujit Basu, Peter Bauer‐Gottwein, Matthias Becker, B. D. Beckley, Nicole Bellefond, Т. В. Белоненко, Mounir Benkiran, Touati Benkouider, Ralf Bennartz, Jérôme Benveniste, Nicolas Bercher, Muriel Berge-Nguyen, João H. Bettencourt, Fabien Blarel, Alejandro Blazquez, Denis Blumstein, Pascal Bonnefond, Franck Borde, Jérôme Bouffard, F. Boy, Jean‐Paul Boy, C. Brachet, Pierre Brasseur, Alexander Braun, Luca Brocca, David Brockley, Laurent Brodeau, Shannon Brown, Sean Bruinsma, Anna Bulczak, Sammie Buzzard, Madeleine Cahill, Stéphane Calmant, Michel Calzas, Stefania Camici, Mathilde Cancet, Hugues Capdeville, C. C. Carabajal, Loren Carrère, Anny Cazenave, Eric P. Chassignet, Prakash Chauhan, S. Cherchali, T. K. Chereskin, Cécile Cheymol, Daniele Ciani, Paolo Cipollini, Francesca Cirillo, Emmanuel Cosme, Steve Coss, Yuri Cotroneo, David Cotton, Alexandre Couhert, Sophie Coutin-Faye, Jean-François Crétaux, Frédéric Cyr, Francesco d’Ovidio, José Darrozes, Cédric David, Nadim Dayoub, Danielle De Staerke, Xiaoli Deng, Shailen Desai, Jean-Damien Desjonquères, Denise Dettmering, Alessandro Di Bella, Lara Díaz‐Barroso, Gérald Dibarboure, H. B. Dieng, Salvatore Dinardo, Henryk Dobslaw, Guillaume Dodet, Andrea M. Doglioli, Alessio Domeneghetti, David Donahue, Shenfu Dong, Craig Donlon
Abstract
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.