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201. A preliminary tectonic fabric chart of the Indian Ocean

Author

J. Y. Royer, David T. Sandwell, and John G. Sclater

Subjects
Lineation, Ocean surface topography, Geoid, Vertical deflection, General Earth and Planetary Sciences, Bathymetry, Geodesy, Magnetic anomaly, Geology, Seafloor spreading, Seismology, Seabed
Abstract

We present a preliminary tectonic chart of the Indian Ocean based on a joint compilation of bathymetric data, magnetic anomaly data and Geosat altimetry data. Satellite altimeters such as Geosat map the topography of the equipotential sea surface or marine geoid. Our interpretation of the GEOSAT data is based on an analysis of the first derivative of the geoid profiles (i.e. deflection of the vertical profiles). Because of the high correlation between the vertical deflection (at wavelength

Published
1989
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203. Field Tests of SEASAT Bathymetric Detections

Author

D. C. Schwank, P. W. Fell, R. K. Perry, B. Zondek, A. Lazarewicz, David F. Naar, David T. Sandwell, B. Keating, D. Handschmacher, Richard Hey, Peter R. Vogt, and Norman Z. Cherkis

Subjects
Satellite radar, geography, geography.geographical_feature_category, Seamount, Field tests, Geodesy, law.invention, Radar altimeter, law, Satellite altimetry, Bathymetry, Southern Hemisphere, Geology, Inertial navigation system
Abstract

Knowledge of the locations and sizes of seamounts is of great importance in applications such as inertial navigation and ocean mining. The quality and density of bathymetry data in the equatorial regions and the southern hemisphere are, unfortunately, highly variable. Our present knowledge of bathymetry, and in particular of seamount locations and characteristics, is based upon ship surveys, which are both time-consuming and expensive. It is likely that a significant number of uncharted seamounts exist throughout the oceans, and remote-sensing techniques may be the most effective means of locating them.

Published
1984
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204. Applications of Satellite Altimetry to Oceanography and Geophysics

Author

John J. McCarthy, Thomas V. Martin, David T. Sandwell, B. C. Douglas, R. E. Cheney, and James G. Marsh

Subjects
Dynamic height, Ocean surface topography, Oceanography, Geoid, Bathymetry, Sea-surface height, Geophysics, Altimeter, Physical oceanography, Geodesy, Sea level, Geology
Abstract

Satellite-borne altimeters have had a profound impact on geodesy, geophysics, and physical oceanography. To first order approximation, profiles of sea surface height are equivalent to the geoid and are highly correlated with seafloor topography for wavelengths less than 1000 km. Using all available Geos-3 and Seasat altimeter data, mean sea surfaces and geoid gradient maps have been computed for the Bering Sea and the South Pacific. When enhanced using hill-shading techniques, these images reveal in graphic detail the surface expression of seamounts, ridges, trenches, and fracture zones. Such maps are invaluable in oceanic regions where bathymetric data are sparse. Superimposed on the static geoid topography is dynamic topography due to ocean circulation. Temporal variability of dynamic height due to oceanic eddies can be determined from time series of repeated altimeter profiles. Maps of sea height variability and eddy kinetic energy derived from Geos-3 and Seasat altimetry in some cases represent improvements over those derived from standard oceanographic observations. Measurement of absolute dynamic height imposes stringent requirements on geoid and orbit accuracies, although existing models and data have been used to derive surprisingly realistic global circulation solutions. Further improvement will only be made when advances are made in geoid modeling and precision orbit determination. In contrast, it appears that use of altimeter data to correct satellite orbits will enable observation of basin-scale sea level variations of the type associated with climatic phenomena.

Published
1984
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205. Altimetry for the future: Building on 25 years of progress

Author

Francesco d'Ovidio, Pierre Féménias, Sean Bruinsma, Felix Perosanz, Jerome Bouffard, S. Desai, Alexandre Couhert, Tatyana V. Belonenko, Sinead L. Farrell, Masafumi Kamachi, Rémi Laxenaire, Alexei V. Kouraev, M-Isabelle Pujol, Sandrine Mulet, Ciprian Spatar, Pablo Nilo Garcia, Loren Carrere, Vinca Rosmorduc, Michel Calzas, Marcello Passaro, Francesca Cirillo, Mathieu Hamon, Enrico Ser-Giacomi, Jida Wang, Raj Kumar, Stelios P. Mertikas, Luisella Giulicchi, Eric Jeansou, Benoit Legresy, Corinne Salaün, Donald Richardson, Martin Horwath, Sujit Basu, Rosemary Morrow, Jean-Damien Desjonquères, François Barlier, Cédric Brachet, Cécile Manfredi, Yves Morel, P. K. Gupta, Nicolas Taburet, Ferran Gibert, Anny Cazenave, Sung Yong Kim, Christopher Pearson, Lin Gilbert, Brian D. Dushaw, Johnny A. Johannessen, René Forsberg, Joël Dorandeu, Luciana Fenoglio, Denis Blumstein, C. K. Shum, Debadatta Swain, Stephan Paul, Valerii Vuglinskii, Marco Meloni, Hilary Wilson, Laurent Testut, Sebatian B. Simonsen, John Moyard, Fabien Léger, Andy Shaw, Abdolnabi Abdeh Kolahchi, Andrea Scozzari, Jan Even Øie Nilsen, Anna I. Bulczak, Valerio Poggiali, Rashmi Shah, John Wilkin, Steven Baker, Patrice Klein, Touati Benkouider, Claire Macintosh, Sarah T. Gille, Alexandre Guerin, Gilles Tavernier, Josh K. Willis, Jérôme Benveniste, Cedric Tourain, Emil V. Stanev, Praveen K. Thakur, Lionel Fichen, Céline Tison, Hans Ngodock, Shenfu Dong, Yuanyuan Jia, Sergey A. Lebedev, Nadia Ayoub, Constantin Mavrocordatos, Cédric H. David, Salvatore Dinardo, Yongjun Jia, Berguzar Oztunali Ozbahceci, Sara Fleury, Matthias Raynal, Yannice Faugère, Kathryn A. Kelly, Christian Schwatke, Craig Donlon, Etienne Poirier, Margaret Srinivasan, Remko Scharroo, Helena Antich, Barbara J. Ryan, Sergey V. Prants, Malcolm McMillan, Frédérique Rémy, David T. Sandwell, Annick Sylvestre-baron, Pascal Bonnefond, Fabien Blarel, Mounir Benkiran, Remi Tailleux, Marco Restano, Thierry Guinle, Stefano Vignudelli, Eric Leuliette, Madeleine Cahill, Ali Rami, Saulo Soares, Sophie Le Gac, Bàrbara Barceló-Llull, Claudia C. Carabajal, Veit Helm, Eva Alou-Font, Alejandro Blazquez, David Griffin, Habib B. Dieng, Prakash Chauhan, Albert Garcia-Mondejar, Christian Massari, Christopher J. Banks, Joana Fernandes, Blake A Walter, Nathalie Steunou, Karina Nielsen, Elena Zakharova, Bob Su, Stefania Camici, Frédérique Seyler, Fukai Peng, Denis L. Volkov, Wim Simons, Pieter Visser, Sophie Coutin-Faye, Lionel Gourdeau, Jesús Gómez-Enri, Andreas Schiller, Brian K. Arbic, Svetlana Karimova, Christine Gommenginger, Fanny Piras, Angélique Melet, Steve Coss, Meric Srokosz, Robert G. King, Frédéric Frappart, Fernando S. Paolo, Anna Klos, José Darrozes, Shannon Brown, Loreley Selene Lago, Susheel Adusumilli, Jay F. Shriver, Yves Quilfen, Martina Idžanović, Bernd Uebbing, Daniel Medeiros Moreira, Byron D. Tapley, R. Keith Raney, Frank G. Lemoine, Angelica Tarpanelli, Lara Díaz-Barroso, Jean-François Crétaux, Jean Tournadre, Tamlin M. Pavelsky, Sébastien Trilles, Carolina Nogueira Loddo, Léa Lasson, Stine Kildegaard Rose, Luc Lenain, Philip L. Woodworth, Marie-laure Frery, Saleh Abdalla, Bo Qiu, Stefan Hendricks, Mikhail A. Sokolovskiy, Antonio Sánchez-Román, Martin G. Scharffenberg, Per Knudsen, Andrew Shepherd, Michiel Otten, Sammie Buzzard, Philippe Schaeffer, Nicolas Picot, Luca Brocca, Michel Tsamados, Danielle De Staerke, Frederic Vivier, Nicole Bellefond, Jean-François Minster, Telmo Vieira, Brian D. Beckley, Stylianos Flampouris, Nadya Vinogradova Shiffer, Sergei Rudenko, Camille Noûs, Sabine Arnault, Frédéric Cyr, Liguang Jiang, Nicolas Bercher, Teresa K. Chereskin, Katsumi Takayama, Julienne Stroeve, Andrea Doglioli, Joanna Staneva, Stéphane Calmant, T. Moreau, Julien Le Sommer, David R. Donahue, Nadim Dayoub, Clement Ubelmann, Annie Richardson, Estelle Obligis, Laurent Brodeau, Catherine Prigent, Gérald Dibarboure, Simón Ruiz, LuAnne Thompson, Muriel Berge-Nguyen, Martina Ricko, Hugues Capdeville, Sammy Metref, Roshin P. Raj, Suchandra Aich Bhowmick, Andrey G. Kostianoy, Guillermina Paniagua, Mathilde Cancet, Eero Rinne, Sonia Ponce de León, Cédric Falco, Jianqiang Liu, Lucile Gaultier, Julia Gaudelli, Thierry Medina, Vadim Zinchenko, William Llovel, Eric P. Chassignet, Raymond Zaharia, Svetlana Y. Erofeeva, Lifeng Bao, Ole Baltazar Andersen, Emmanuel Cosme, Anna E. Hogg, Yohanes Budi Sulistioadi, Artur Gil, O. Laurain, Walter H. F. Smith, Ngan Tran, Pierre-Yves Le Traon, Laura Gomez-Navarro, Adrien Paris, Thomas W. K. Armitage, Alejandro Egido, Christopher Watson, João H. Bettencourt, Giuseppe Aulicino, Philippe Escudier, Fangfang Yao, Marco Fornari, Guoqi Han, Florent Lyard, Elisabeth Remy, Lotfi Aouf, Michele Scagliola, Martin Saraceno, Paolo Filippucci, Chao Wang, Zhongxiang Zhao, Juliette Lambin, Evan Mason, Ines Otosaka, Daniele Ciani, Raúl A. Guerrero, Ralf Bennartz, Michael Ablain, Fabrice Hernandez, Xiaoli Deng, John Lillibridge, Oscar Vergara, Marina Levy, Christine Drezen, Pierre Thibaut, Ronan Fablet, Bill Townsend, David Cotton, Sabrina Speich, Clara Lázaro, R. S. Nerem, Danièle Hauser, Pierre Exertier, Yuri Cotroneo, Henryk Dobslaw, Alessandro Di Bella, Karina von Schuckmann, Saskia Esselborn, Benjamin D. Gutknecht, Cecile Marie Margaretha Kittel, Rolf Koenig, Peter Bauer-Gottwein, Franck Borde, Alexander Braun, Christine Provost, Thomas Slater, Laiba Amarouche, Nikolai Maximenko, Raphael Schneider, Victor Zlotnicki, Jacques Verron, Sergei I. Badulin, Andreas Groh, Denise Dettmering, Mark R. Drinkwater, S. Cherchali, Marc Naeije, Fernando Niño, Alessio Domeneghetti, Kuo Hsin Tseng, François Boy, Rashmi Sharma, Laurent Soudarin, Peter A. E. M. Janssen, Robert Ricker, Frédéric Marin, Ananda Pascual, Eduard Makhoul Varona, Yongsheng Zhang, Pierrik Vuilleumier, Louise Sandberg Sørensen, Guillaume Dodet, Pascale Ferrage, Ramiro Ferrari, Yves Du Penhoat, Rodrigo Cauduro Dias de Paiva, S. Labroue, Camila Indira Artana, Joaquín Tintoré, David Brockley, Thierry Penduff, Paolo Cipollini, Augusto Getirana, Cecile Cheymol, Edward D. Zaron, Silvia Barbetta, Pierre Brasseur, Benoit Meyssignac, Matthias Becker, Kehan Yang, Juan Gabriel Fernández, Jean Paul Boy, European Centre for Medium-Range Weather Forecasts (ECMWF), Soil Conservation and Watershed Management Research Institute (SCWRMI), Agricultural Research, Education and Extension Organisation (AREEO ), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Space Applications Centre [Ahmedabad] (SAC), Indian Space Research Organisation (ISRO), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), National Space Institute [Lyngby] (DTU Space), Technical University of Denmark [Lyngby] (DTU), Institut Mediterrani d'Estudis Avancats (IMEDEA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de las Islas Baleares (UIB), Météo France, Department of Earth and Environmental Sciences [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Variabilité de l'Océan et de la Glace de mer (VOG), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Mercator Océan, Société Civile CNRS Ifremer IRD Météo-France SHOM, Universita degli studi di Napoli 'Parthenope' [Napoli], Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), P.P. Shirshov Institute of Oceanology (SIO), Russian Academy of Sciences [Moscow] (RAS), Department of Space and Climate Physics [UCL London], Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL)-University College of London [London] (UCL), National Oceanography Centre (NOC), Institute of Geodesy and Geophysics [Wuhan], Chinese Academy of Sciences [Wuhan Branch], Istituto di Ricerca per la Protezione Idrogeologica [Perugia] (IRPI), Consiglio Nazionale delle Ricerche [Roma] (CNR), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), DTU Environment, Department of Environmental Engineering, Technische Universität Darmstadt (TU Darmstadt), Centre National d'Études Spatiales [Toulouse] (CNES), St Petersburg State University (SPbU), Agence Spatiale Algérienne = Algerian Space Agency (ASAL), Vanderbilt University [Nashville], European Space Research Institute (ESRIN), European Space Agency (ESA), Centre for Marine Technology and Ocean Engineering (CENTEC), Instituto Superior Técnico, Universidade Técnica de Lisboa (IST), Systèmes de Référence Temps Espace (SYRTE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), European Space Research and Technology Centre (ESTEC), Ecole et Observatoire des Sciences de la Terre (EOST), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INSU Division Technique de l'INSU [Site de Brest], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Queen's University [Kingston, Canada], OceanNext, Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institute of Oceanology, Polish Academy of Sciences (IO-PAN), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Centre for Polar Observation and Modelling (CPOM), Natural Environment Research Council (NERC), Australian Institute of Marine Science [Townsville] (AIMS Townsville), Australian Institute of Marine Science (AIMS), NOVELTIS [Sté], Science Systems and Applications, Inc. [Hampton] (SSAI), International Space Science Institute [Bern] (ISSI), Center for Ocean-Atmospheric Prediction Studies (COAPS), Florida State University [Tallahassee] (FSU), Indian Institute of Remote Sensing (IIRS), Istituto di Science Marine (ISMAR ), Consiglio Nazionale delle Ricerche (CNR), European Centre for Space Applications and Telecommunications (ECSAT), Airbus Group [Germany], Airbus [France], School of Earth Sciences [Columbus], Ohio State University [Columbus] (OSU), Satellite Oceanographic Consultants Ltd (SATOC), Northwest Atlantic Fisheries Centre (NWAFC), Fisheries and Oceans Canada (DFO), Processus et interactions de fine échelle océanique (PROTEO), School of Engineering [Callaghan], University of Newcastle [Australia] (UoN), Deutsches Geodätisches Forschungsinstitut (DGFI-TUM), Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), SOCIB Balearic Islands Coastal Ocean Observing and Forecasting System, German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Department of Civil Chemical Environmental and Materials Engineering [Bologna] (DICAM), University of Bologna, NOAA Office of Satellite and Product Operations (OSPO), NOAA National Environmental Satellite, Data, and Information Service (NESDIS), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML), National Oceanic and Atmospheric Administration (NOAA), Oregon State University (OSU), IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Département Mathematical and Electrical Engineering (IMT Atlantique - MEE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Equipe Observations Signal & Environnement (Lab-STICC_OSE), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Université de Perpignan Via Domitia (UPVD), Department of Geographical Sciences [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Institut für Geodäsie und Geoinformationstechnik, Technische Universität Berlin (TU), Interdisciplinary Centre of Marine and Environmental Research [Matosinhos, Portugal] (CIIMAR), Universidade do Porto, Centro de Investigaciones del Mar y la Atmósfera (CIMA), Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Institut für Planetare Geodäsie, Lohrmann-Observatorium, Technische Universität Dresden = Dresden University of Technology (TU Dresden), Universidad Nacional de Mar del Plata [Mar del Plata] (UNMdP), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Environmental Fluid Mechanics Laboratory [Daejeon] (EFML), Korea Advanced Institute of Science and Technology (KAIST), Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Austral, Boréal et Carbone (ABC), Kansas State University, University of North Carolina [Chapel Hill] (UNC), University of North Carolina System (UNC), University of Tasmania [Hobart, Australia] (UTAS), Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers), Institute of Arctic and Alpine Research (INSTAAR), University of Colorado [Boulder], Water Problems Institute (WPI), the Russian Academy of Sciences [Moscow, Russia] (RAS), Portland State University [Portland] (PSU), Applied Physics Laboratory [Seattle] (APL-UW), University of Washington [Seattle], Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Météo-France Direction Interrégionale Sud-Est (DIRSE), Météo-France, Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Università degli Studi di Napoli 'Parthenope' = University of Naples (PARTHENOPE), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Technische Universität Darmstadt - Technical University of Darmstadt (TU Darmstadt), Agence Spatiale Européenne = European Space Agency (ESA), University of Newcastle [Callaghan, Australia] (UoN), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), University of Bologna/Università di Bologna, IMT Atlantique (IMT Atlantique), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Technical University of Berlin / Technische Universität Berlin (TU), Universidade do Porto = University of Porto, Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Group on Earth Observations (GEO), Institute of Arctic Alpine Research [University of Colorado Boulder] (INSTAAR), Department of Water Resources, UT-I-ITC-WCC, Faculty of Geo-Information Science and Earth Observation, Abdalla S., Abdeh Kolahchi A., Ablain M., Adusumilli S., Aich Bhowmick S., Alou-Font E., Amarouche L., Andersen O.B., Antich H., Aouf L., Arbic B., Armitage T., Arnault S., Artana C., Aulicino G., Ayoub N., Badulin S., Baker S., Banks C., Bao L., Barbetta S., Barcelo-Llull B., Barlier F., Basu S., Bauer-Gottwein P., Becker M., Beckley B., Bellefond N., Belonenko T., Benkiran M., Benkouider T., Bennartz R., Benveniste J., Bercher N., Berge-Nguyen M., Bettencourt J., Blarel F., Blazquez A., Blumstein D., Bonnefond P., Borde F., Bouffard J., Boy F., Boy J.-P., Brachet C., Brasseur P., Braun A., Brocca L., Brockley D., Brodeau L., Brown S., Bruinsma S., Bulczak A., Buzzard S., Cahill M., Calmant S., Calzas M., Camici S., Cancet M., Capdeville H., Carabajal C.C., Carrere L., Cazenave A., Chassignet E.P., Chauhan P., Cherchali S., Chereskin T., Cheymol C., Ciani D., Cipollini P., Cirillo F., Cosme E., Coss S., Cotroneo Y., Cotton D., Couhert A., Coutin-Faye S., Cretaux J.-F., Cyr F., d'Ovidio F., Darrozes J., David C., Dayoub N., De Staerke D., Deng X., Desai S., Desjonqueres J.-D., Dettmering D., Di Bella A., Diaz-Barroso L., Dibarboure G., Dieng H.B., Dinardo S., Dobslaw H., Dodet G., Doglioli A., Domeneghetti A., Donahue D., Dong S., Donlon C., Dorandeu J., Drezen C., Drinkwater M., Du Penhoat Y., Dushaw B., Egido A., Erofeeva S., Escudier P., Esselborn S., Exertier P., Fablet R., Falco C., Farrell S.L., Faugere Y., Femenias P., Fenoglio L., Fernandes J., Fernandez J.G., Ferrage P., Ferrari R., Fichen L., Filippucci P., Flampouris S., Fleury S., Fornari M., Forsberg R., Frappart F., Frery M.-L., Garcia P., Garcia-Mondejar A., Gaudelli J., Gaultier L., Getirana A., Gibert F., Gil A., Gilbert L., Gille S., Giulicchi L., Gomez-Enri J., Gomez-Navarro L., Gommenginger C., Gourdeau L., Griffin D., Groh A., Guerin A., Guerrero R., Guinle T., Gupta P., Gutknecht B.D., Hamon M., Han G., Hauser D., Helm V., Hendricks S., Hernandez F., Hogg A., Horwath M., Idzanovic M., Janssen P., Jeansou E., Jia Y., Jiang L., Johannessen J.A., Kamachi M., Karimova S., Kelly K., Kim S.Y., King R., Kittel C.M.M., Klein P., Klos A., Knudsen P., Koenig R., Kostianoy A., Kouraev A., Kumar R., Labroue S., Lago L.S., Lambin J., Lasson L., Laurain O., Laxenaire R., Lazaro C., Le Gac S., Le Sommer J., Le Traon P.-Y., Lebedev S., Leger F., Legresy B., Lemoine F., Lenain L., Leuliette E., Levy M., Lillibridge J., Liu J., Llovel W., Lyard F., Macintosh C., Makhoul Varona E., Manfredi C., Marin F., Mason E., Massari C., Mavrocordatos C., Maximenko N., McMillan M., Medina T., Melet A., Meloni M., Mertikas S., Metref S., Meyssignac B., Minster J.-F., Moreau T., Moreira D., Morel Y., Morrow R., Moyard J., Mulet S., Naeije M., Nerem R.S., Ngodock H., Nielsen K., Nilsen J.E.O., Nino F., Nogueira Loddo C., Nous C., Obligis E., Otosaka I., Otten M., Oztunali Ozbahceci B., P. Raj R., Paiva R., Paniagua G., Paolo F., Paris A., Pascual A., Passaro M., Paul S., Pavelsky T., Pearson C., Penduff T., Peng F., Perosanz F., Picot N., Piras F., Poggiali V., Poirier E., Ponce de Leon S., Prants S., Prigent C., Provost C., Pujol M.-I., Qiu B., Quilfen Y., Rami A., Raney R.K., Raynal M., Remy E., Remy F., Restano M., Richardson A., Richardson D., Ricker R., Ricko M., Rinne E., Rose S.K., Rosmorduc V., Rudenko S., Ruiz S., Ryan B.J., Salaun C., Sanchez-Roman A., Sandberg Sorensen L., Sandwell D., Saraceno M., Scagliola M., Schaeffer P., Scharffenberg M.G., Scharroo R., Schiller A., Schneider R., Schwatke C., Scozzari A., Ser-giacomi E., Seyler F., Shah R., Sharma R., Shaw A., Shepherd A., Shriver J., Shum C.K., Simons W., Simonsen S.B., Slater T., Smith W., Soares S., Sokolovskiy M., Soudarin L., Spatar C., Speich S., Srinivasan M., Srokosz M., Stanev E., Staneva J., Steunou N., Stroeve J., Su B., Sulistioadi Y.B., Swain D., Sylvestre-baron A., Taburet N., Tailleux R., Takayama K., Tapley B., Tarpanelli A., Tavernier G., Testut L., Thakur P.K., Thibaut P., Thompson L., Tintore J., Tison C., Tourain C., Tournadre J., Townsend B., Tran N., Trilles S., Tsamados M., Tseng K.-H., Ubelmann C., Uebbing B., Vergara O., Verron J., Vieira T., Vignudelli S., Vinogradova Shiffer N., Visser P., Vivier F., Volkov D., von Schuckmann K., Vuglinskii V., Vuilleumier P., Walter B., Wang J., Wang C., Watson C., Wilkin J., Willis J., Wilson H., Woodworth P., Yang K., Yao F., Zaharia R., Zakharova E., Zaron E.D., Zhang Y., Zhao Z., Zinchenko V., Zlotnicki V., Technical University of Munich (TUM), European Space Agency, National Aeronautics and Space Administration (US), Centre National D'Etudes Spatiales (France), Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Lab-STICC_IMTA_CID_TOMS, Université de Brest (UBO)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université Bretagne Loire (UBL)-Centre National de la Recherche Scientifique (CNRS)-Université de Bretagne Sud (UBS)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Brest (UBO)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université Bretagne Loire (UBL)-Centre National de la Recherche Scientifique (CNRS)-Université de Bretagne Sud (UBS)-École Nationale d'Ingénieurs de Brest (ENIB), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Cryospheric science, Atmospheric Science, Earth observation, 010504 meteorology & atmospheric sciences, UT-Hybrid-D, Oceanography, 01 natural sciences, Cryospheric sciences, SDG 13 - Climate Action, Aerospace & Aeronautics, Cryosphere, Satellite altimetry, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Geodetic datum, ddc, Ocean surface topography, Geophysics, Section (archaeology), [SDE]Environmental Sciences, Astronomical and Space Sciences, Geology, Altimetria espacial, Coastal oceanography, Meteorology, Hidrologia, Aerospace Engineering, ITC-HYBRID, 0103 physical sciences, Geoid, Oceonografia, Sea level, SDG 14 - Life Below Water, 14. Life underwater, Altimeter, Criosfera, Life Below Water, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Mechanical Engineering, Hydrology, Astronomy and Astrophysics, Climate Action, Earth system science, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, ITC-ISI-JOURNAL-ARTICLE, General Earth and Planetary Sciences
Abstract

International Altimetry Team., 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., 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.

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206. An abrupt change in ridge axis gravity with spreading rate

Author

David T. Sandwell and Christopher Small

Subjects
Atmospheric Science, Hydrostatic pressure, Trough (geology), Soil Science, Aquatic Science, Oceanography, Gravitation, Geochemistry and Petrology, Lithosphere, Earth and Planetary Sciences (miscellaneous), Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, High amplitude, digestive, oral, and skin physiology, Paleontology, Forestry, Geodesy, Geophysics, Ridge push, Space and Planetary Science, Ridge, Satellite altimetry, Geology
Abstract

A total of 44 Geosat profiles over ridges with spreading rates ranging from 14 to 155 mm/yr were analyzed. In agreement with previous studies, it is found that slow spreading ridges usually have high amplitude gravity troughs, while fast spreading ridges are characterized by low-amplitude ridge axis highs. Unexpectedly, it is found that the transition from axial trough to axial high occurs abruptly at a spreading rate of 60-70 mm/yr. Ridge axis gravity signatures are highly variable for rates less than 65 mm/yr and very uniform at higher rates. The transition of the gravity signature appears to get more abrupt than the transition of the topographic signature, suggesting an abrupt change in the style of isostatic compensation with spreading rate. Published models of ridge axis dynamics do not explain this sharp transition.

Published
1989
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207. Reply [to 'Comment on ‘Seasonal variation in wind speed and sea state from global satellite measurements’ by D. Sandwell and R. Agreen']

Author

Russell W. Agreen and David T. Sandwell

Subjects
Atmospheric Science, Ecology, Meteorology, Paleontology, Soil Science, Forestry, Sea state, Aquatic Science, Seasonality, Oceanography, medicine.disease, Wind speed, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Climatology, Earth and Planetary Sciences (miscellaneous), medicine, Environmental science, Satellite, Earth-Surface Processes, Water Science and Technology
Published
1985
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208. The negative gravity field over the 85°E ridge

Author

David T. Sandwell, Char-Shine Liu, and Joseph R. Curray

Subjects
Atmospheric Science, Gravity (chemistry), Soil Science, Aquatic Science, Oceanography, Gravity anomaly, Geochemistry and Petrology, Lithosphere, Earth and Planetary Sciences (miscellaneous), Petrology, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, Paleontology, Forestry, Flexural rigidity, Sedimentary basin, Geophysics, Ridge push, Space and Planetary Science, Ridge, Isopach map, Geology, Seismology
Abstract

Two north-south ridges in the basement topography of the Bay of Bengal may be observed on an isopach map at 85 and at 90 deg E. Free-air gravity anomaly profiles across the region show a strong gravity low (about -60 mGal) over the 85 deg E ridge, and a gravity high over the other. Using a simple two-stage loading model, the negative gravity anomaly over the 85 deg E ridge is explained as a direct consequence of sediment loading, and the flexural rigidity of the lithosphere when the ridge was formed is estimated to have been about 180 times less than the flexural rigidity during the sediment loading. An approximate relationship between flexural rigidity and crustal age shows that the 85 deg E ridge was formed on relatively young lithosphere, 5-15 million years old, and that it was buried when the lithosphere was 40-80 million years old. The alteration of the gravity field by a thick layer of sediments may occur in other large sedimentary basins or along continental margins.

Published
1982
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209. On the source of cross-grain lineations in the central Pacific gravity field

Author

David T. Sandwell and David C. McAdoo

Subjects
Atmospheric Science, Gravity (chemistry), Ecology, Paleontology, Soil Science, Forestry, Aquatic Science, Oceanography, Geodesy, Sonar, Gravity anomaly, Lineation, Geophysics, Gravitational field, Space and Planetary Science, Geochemistry and Petrology, Coincident, Lithosphere, Earth and Planetary Sciences (miscellaneous), Bathymetry, Geology, Seismology, Earth-Surface Processes, Water Science and Technology
Abstract

The source of cross-grain lineations in marine gravity field observed in central Pacific was investigated by comparing multiple collinear gravity profiles from Geosat data with coincident bathymetry profiles, in the Fourier transform domain. Bathymetric data were collected by multibeam sonar systems operating from two research vessels, one in June-August 1985, the other in February and March 1987. The results of this analysis indicate that the lineations are superficial features that appear to result from a combination of subsurface and surface loads supported by a thin (2 km to 5 km) lithosphere.

Published
1989
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210. Thermal stress and the spacings of transform faults

Author

David T. Sandwell

Subjects
Atmospheric Science, geography, geography.geographical_feature_category, Ecology, Paleontology, Soil Science, Transform fault, Forestry, Aquatic Science, Oceanography, Bathymetric chart, Stress (mechanics), Geophysics, Thermoelastic damping, Ridge push, Space and Planetary Science, Geochemistry and Petrology, Lithosphere, Ridge, Earth and Planetary Sciences (miscellaneous), Intraplate earthquake, Geology, Seismology, Earth-Surface Processes, Water Science and Technology
Abstract

Bathymetric charts are used with satellite altimeter profiles to locate major ridge-transform intersections along five spreading ridges. The ridges are the Mid-Atlantic Ridge, the East Pacific Rise, the Chile Rise, the Pacific-Antarctic Rise, and the Southeast Indian Ridge. Analysis of these data show spacings between transform faults W increase linearly with spreading rate ν (W/ν = 6.28 m.y.). This linear correlation is explained by a thermoelastic model of a cooling strip of lithosphere spreading at a rate ν. The traction-free boundaries of the thin elastic strip simulate cracks in the lithosphere at transform faults. A two-dimensional thermoelastic solution for the in-plane stress shows the largest stress component is tensional and parallel to the ridge. Stresses are zero at the ridge and increase as (age)½ to a maximum value at an age of W/4ν. All stress components are small for ages greater than W/ν. When the transform spacing is large compared with the spreading rate (W/ν > 100 m.y.) thermal stresses exceed the strength of the lithosphere for ages between 0 and 30 Ma. The observed maximum ratio of transform spacing to spreading rate (W/ν = 10 m.y.) results in low thermal stresses that only exceed the strength of the lithosphere for ages less than 1 Ma. Thus transform faults relieve most of the thermal stress. Model predictions also agree with earthquake studies showing that normal faults in young lithosphere have tensional axes aligned with the ridge. Moreover, oceanic intraplate earthquakes rarely occur in lithosphere older than 30 Ma as predicted by the model. These and other geophysical observations confirm Turcotte's hypothesis that transform faults are thermal contraction cracks.

Published
1986
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211. Geoid height versus age for symmetric spreading ridges

Author

David T. Sandwell and Gerald Schubert

Subjects
Atmospheric Science, Ecology, North Atlantic Deep Water, Paleontology, Soil Science, Forestry, Aquatic Science, Physical oceanography, Oceanography, Geodesy, Boundary layer, Ocean surface topography, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Climatology, Geoid, Earth and Planetary Sciences (miscellaneous), Thermohaline circulation, Altimeter, Geology, Seabed, Earth-Surface Processes, Water Science and Technology
Abstract

Geoid height-age relations have been extracted from Geos 3 altimeter data for large areas in the North Atlantic, South Atlantic, southeast Indian, and southeast Pacific oceans. Except for the southeast Pacific area, geoid height decreases approximately linearly with the age of the ocean floor for ages less than about 80 m.y. in agreement with the prediction of an isostatically compensated thermal boundary layer model (Haxby and Turcotte, 1978). The geoid-age data for 0 to 80 m.y. are consistent with constant slopes of -0.094 + or - -0.131 + or - 0.041, and -0.149 + or - 0.028 m/m.y. for the South Atlantic, southeast Indian, and North Atlantic regions, respectively. For ages greater than 80 m.y. the geoid-age relation for the North Atlantic is nearly flat, indicating a reduction in the rate of boundary layer thickening with age. The uncertainties in the geoid slope-age estimates are positively correlated with spreading velocity.

Published
1980
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212. Seasonal variation in wind speed and sea state from global satellite measurements

Author

Russell W. Agreen and David T. Sandwell

Subjects
Atmospheric Science, Ecology, Global wind patterns, Northern Hemisphere, Paleontology, Soil Science, Forestry, Westerlies, Sea state, Aquatic Science, Oceanography, Atmospheric sciences, Wind speed, Geophysics, Prevailing winds, Space and Planetary Science, Geochemistry and Petrology, Climatology, Wind shear, Earth and Planetary Sciences (miscellaneous), Environmental science, Southern Hemisphere, Earth-Surface Processes, Water Science and Technology
Abstract

The GEOS 3 altimeter, which collected data intermittently for nearly 4 years, has measured significant wave heights and surface wind speeds over most of the world's oceans. Using these data, we have constructed contour maps of spatial variations in sea state and wind speed for winter and summer. To obtain reliable averages in the southern oceans, we low-pass filtered the data using a two-dimensional Gaussian filter with a half width of 600 km. The wind speed maps show that the zonal surface wind patterns, such as the westerlies, the horse latitudes, the trade winds, and the doldrums, shift south by about 10° between winter and summer. As expected, the highest wind speeds and sea states occur during the winter months in the mid-latitudes, 30°–60°. The most striking feature of the maps, however, is the large asymmetry in the summer to winter variation between the two hemispheres. The largest seasonal variations in sea state and wind speed occur in the northern hemisphere oceans and especially in the North Atlantic, where there is almost a factor of 2 variation. In contrast, the summer to winter variation in wind speed and sea state in the southern hemisphere oceans is relatively small. For example, the summer to winter increase in wind speed at 50°S is less than 10%, while at 50°N it is more than 50%. This differing variability can be attributed to the asymmetric distribution of continental area between the two hemispheres and the low effective heat capacity of the continents relative to the oceans.

Published
1984
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213. Geoid height-age relation from SEASAT altimeter profiles across the Mendocino Fracture Zone

Author

Gerald Schubert and David T. Sandwell

Subjects
Atmospheric Science, Ecology, Paleontology, Soil Science, Forestry, Fracture zone, Geophysics, Aquatic Science, Oceanography, Geodesy, Seafloor spreading, Lineation, Boundary layer, Space and Planetary Science, Geochemistry and Petrology, Lithosphere, Geoid, Earth and Planetary Sciences (miscellaneous), Undulation of the geoid, Altimeter, Geology, Earth-Surface Processes, Water Science and Technology
Abstract

Twenty-eight Seasat altimeter profiles crossing the Mendocino Fracture Zone are used together with seafloor ages determined from magnetic lineations to estimate the change in oceanic geoid height with age, between ages of 15 and 135 m.y. An unbiased estimate of the overall geoid offset along each profile is determined from a least-squares fit of the along-track derivative of the geoid to the geoid slope predicted from a simple two-layer gravitational edge effect model. Uncertainties based upon the statistical properties of each profile are also determined. A geoid slope-age relation is constructed by normalizing the geoid offsets and uncertainties by the age offsets. The results are in agreement with geoid slope-age relations determined from symmetrically spreading ridges (Sandwell and Schubert, 1980). However, the fracture zone estimates have smaller uncertainties and show less scatter. A comparison of these results with the geoid slope-age prediction of the boundary layer cooling model shows that the thermal structure begins to deviate from this model at an early age (20-40 m.y.). A plate cooling model with a thickness of 125 km is most compatible with the geoid slope-age estimates, although significant deviations occur; these may indicate that the lithospheric thermal structure is not entirely age dependent.

Published
1982
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214. Geoid height versus topography for oceanic plateaus and swells

Author

Kevin MacKenzie and David T. Sandwell

Subjects
Atmospheric Science, geography, geography.geographical_feature_category, Ecology, Paleontology, Soil Science, Forestry, Geoid height, Aquatic Science, Oceanography, Geodesy, Swell, Ocean surface topography, Wavelength, Geophysics, Volcano, Airy function, Space and Planetary Science, Geochemistry and Petrology, Geoid, Earth and Planetary Sciences (miscellaneous), Bathymetry, Geology, Earth-Surface Processes, Water Science and Technology
Abstract

Gridded geoid height data (Marsh et al.l, 1986) and gridded bathymetry data (Van Wykhouse, 1973) are used to estimate the average compensation depths of 53 oceanic swells and plateaus. The relationship between geoid height and topography is examined using Airy and thermal compensation models. It is shown that geoid height is linearly related to topography between wavelengths of 400 and 4000 m as predicted by isostatic compensation models. The geoid/topography ratio is dependent on the average depth of compensation. The intermediate geoid/topography ratios of most thermal swells are interpreted as a linear combination of the decaying thermal swell signature and that of the persisting Airy-compensated volcanic edifice.

Published
1989
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215. Marine gravity

Author

David C. McAdoo and David T. Sandwell

Subjects
General Earth and Planetary Sciences
Published
1988
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216. Global nondynamic orbit improvement for altimetric satellites

Author

Bruce C. Douglas, Dennis G. Milbert, and David T. Sandwell

Subjects
Physics, Atmospheric Science, Ground track, Ecology, Crossover, Paleontology, Soil Science, Spherical harmonics, Forestry, Aquatic Science, Frozen orbit, Orbital mechanics, Oceanography, Geodesy, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Harmonics, Earth and Planetary Sciences (miscellaneous), Satellite, Astrophysics::Earth and Planetary Astrophysics, Orbit (control theory), Earth-Surface Processes, Water Science and Technology
Abstract

The largest source of error in satellite altimetry is in the radial position of the satellite. Radial orbit errors of more than a few decimeters prohibit basin-scale studies of sea surface height variability. We explore nondynamic techniques for reducing this error. Sea surface height differences at intersections of satellite altimeter profiles (crossover data) provide a strong constraint on radial orbit error but do not uniquely define it. The portion of orbit error that is a function of latitude and longitude only produces no crossover differences and therefore cannot be recovered with crossover data. Using mathematics (inclination functions) originally developed for satellite dynamics, we determine the entire class of orbit error functions not recoverable with crossover data. These functions are mappings of surface spherical harmonics into the orbit plane. For example, the l = 1, m = 0 surface harmonic maps into sinusoidal orbit error with a frequency of once per orbit. Nonzonal harmonics map into linear combinations of three or more frequencies that are linked by the inclination functions. Between frequencies of 0 and 2.2 cycles per orbit there are nine orbit error components that cannot be recovered using crossover data. These components are uniquely defined, however, by nine globally distributed radial tracking points. Fewer tracking points are sufficient if a smoothness criteria is applied to the orbit correction curve. Our findings suggest that radial orbit error can be significantly reduced by including a few globally distributed radar reflectors (or transponders) in the tracking network.

Published
1986
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217. Compensation of swells and plateaus in the north Pacific: No direct evidence for mantle convection

Author

David T. Sandwell and Miriam L. Renkin

Subjects
Atmospheric Science, Seamount, Soil Science, Aquatic Science, Oceanography, Mantle convection, Geochemistry and Petrology, Lithosphere, Geoid, Earth and Planetary Sciences (miscellaneous), Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, Paleontology, Forestry, Geophysics, Geodesy, Swell, Ocean surface topography, Wavelength, Space and Planetary Science, Fracture (geology), Geology
Abstract

At intermediate and long wavelengths the ratio of geoid height to topography is sensitive to the depth and mode of compensation. A low geoid/topography ratio ( 8 m/km) in conjunction with a poor correlation between geoid height and topography is evidence of mantle convection. After subtracting a reference geoid from the observed geoid, previous studies have found a regular pattern of geoid highs and lows with a characteristic wavelength of 3000–4000 km. Since these geoid highs and lows were poorly correlated with topography and resulted in very high geoid/topography ratios (10–20 m/km), they were believed to reflect the planform of mantle convection. We show that the regular pattern of geoid highs and lows is an artifact caused by truncating the reference geoid at spherical harmonic degree 10. Since the geoid spectrum is “red,” the residual geoid is dominated by degree 11. When the harmonics of the reference geoid are rolled off gradually, the regular pattern of geoid highs and lows disappears. In the Northeast Pacific, the new residual geoid reflects the lithosphere age offsets across the major fracture zones. In the Northwest Pacific, the residual geoid corresponds to isostatically compensated swells and plateaus. We have calculated the geoid/topography ratio for 10 swells and plateaus and have found a range of compensation depths. The highest geoidAopography ratio of 5.5 m/km occurs on the flanks of the Hawaiian Swell. Intermediate ratios occur in four areas, including the Midway Swell. These intermediate ratios reflect a linear combination of the decaying thermal swell and the increasing volume of Airy-compensated seamounts. Low geoid/topography ratios occur over the remaining five areas (e.g., Emperor Seamounts), reflecting the absence of a thermal swell. Our findings do not support the hypothesis that the planform of mantle convection is evident in the geoid. We see only indirect evidence of thermal plumes reheating the lower lithosphere.

Published
1988
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218. The GPlates Portal: Cloud-Based Interactive 3D Visualization of Global Geophysical and Geological Data in a Web Browser.

Author

R Dietmar Müller, Xiaodong Qin, David T Sandwell, Adriana Dutkiewicz, Simon E Williams, Nicolas Flament, Stefan Maus, and Maria Seton

Subjects
Medicine, Science
Abstract

The pace of scientific discovery is being transformed by the availability of 'big data' and open access, open source software tools. These innovations open up new avenues for how scientists communicate and share data and ideas with each other and with the general public. Here, we describe our efforts to bring to life our studies of the Earth system, both at present day and through deep geological time. The GPlates Portal (portal.gplates.org) is a gateway to a series of virtual globes based on the Cesium Javascript library. The portal allows fast interactive visualization of global geophysical and geological data sets, draped over digital terrain models. The globes use WebGL for hardware-accelerated graphics and are cross-platform and cross-browser compatible with complete camera control. The globes include a visualization of a high-resolution global digital elevation model and the vertical gradient of the global gravity field, highlighting small-scale seafloor fabric such as abyssal hills, fracture zones and seamounts in unprecedented detail. The portal also features globes portraying seafloor geology and a global data set of marine magnetic anomaly identifications. The portal is specifically designed to visualize models of the Earth through geological time. These space-time globes include tectonic reconstructions of the Earth's gravity and magnetic fields, and several models of long-wavelength surface dynamic topography through time, including the interactive plotting of vertical motion histories at selected locations. The globes put the on-the-fly visualization of massive data sets at the fingertips of end-users to stimulate teaching and learning and novel avenues of inquiry.

Published
2016
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