{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2024,8,24]],"date-time":"2024-08-24T20:40:08Z","timestamp":1724532008328},"reference-count":37,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2023,1,8]],"date-time":"2023-01-08T00:00:00Z","timestamp":1673136000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\u2014Portuguese Foundation for Science and Technology","award":["UIDB\/04423\/2020","UIDP\/04423\/2020"]},{"DOI":"10.13039\/501100000844","name":"EU","doi-asserted-by":"publisher","award":["4000134346\/21\/NL\/AD"],"id":[{"id":"10.13039\/501100000844","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"Satellite altimetry has been providing a continuous record of ocean measurements with numerous applications across the entire range of ocean sciences. A reference orbit has been used since 1992 with TOPEX\/Poseidon, which was repeated in the Jason missions, and in the newly launched Sentinel-6 Michael Freilich (in November 2020) to continually monitor the trends of sea level rise and other properties of the sea surface. These multidecadal missions have evolved alongside major technological advances, whose measurements are unified into a single data record owing to continuous intercalibration and validation efforts. However, the new Sentinel-6 provides synthetic aperture radar (SAR) processing, which improves the along-track resolution of conventional altimeters from a few kilometres (e.g., for Jason-3) to about 300 m. This means a major leap in sampling towards higher frequencies of the ocean spectrum, which inevitably means reconciling the assumption of a uniform Brown surface between the footprints of the larger kilometre-scale conventional altimetry and those of the finer-scale SAR altimetry. To explore this issue, this study uses the vantage point of the Sentinel-6\/Jason-3 tandem phase to compare simultaneous sea surface signatures of large-scale Internal Solitary Waves (ISWs) between SAR and conventional altimetry. These waves can modulate the sea surface into arrayed sections of increased and decreased roughness with horizontal scales up to 10 km, which inflict sharp transitions between increased and decreased backscatter in the radar altimeters. It is found that Sentinel-6 can provide more detailed structures of ISWs in standard level-2 products, when compared with those from the conventional Jason-3 (similarly to previous results reported from the SAR altimeter from Sentinel-3). However, a new and striking feature is found when comparing the radar backscatter between Sentinel-6 and Jason-3, which are in opposite phases in the ISWs. These intriguing results are discussed in light of the intrinsically different acquisition geometries of SAR and conventional altimeters as well as possible implications thereof.<\/jats:p>","DOI":"10.3390\/rs15020392","type":"journal-article","created":{"date-parts":[[2023,1,9]],"date-time":"2023-01-09T09:47:08Z","timestamp":1673257628000},"page":"392","source":"Crossref","is-referenced-by-count":6,"title":["Using a Tandem Flight Configuration between Sentinel-6 and Jason-3 to Compare SAR and Conventional Altimeters in Sea Surface Signatures of Internal Solitary Waves"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"http:\/\/orcid.org\/0000-0003-2685-6942","authenticated-orcid":false,"given":"Jorge M.","family":"Magalhaes","sequence":"first","affiliation":[{"name":"Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Terminal de Cruzeiros de Leix\u00f5es, Av. General Norton de Matos, s\/n, 4450-208 Matosinhos, Portugal"},{"name":"Department of Geoscience, Environment and Spatial Planning (DGAOT), Faculty of Sciences, University of Porto, Rua do Campo Alegre, s\/n, 4169-007 Porto, Portugal"}]},{"given":"Ian G.","family":"Lapa","sequence":"additional","affiliation":[{"name":"Department of Geoscience, Environment and Spatial Planning (DGAOT), Faculty of Sciences, University of Porto, Rua do Campo Alegre, s\/n, 4169-007 Porto, Portugal"}]},{"ORCID":"http:\/\/orcid.org\/0000-0002-5704-6021","authenticated-orcid":false,"given":"Adriana M.","family":"Santos-Ferreira","sequence":"additional","affiliation":[{"name":"Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Terminal de Cruzeiros de Leix\u00f5es, Av. General Norton de Matos, s\/n, 4450-208 Matosinhos, Portugal"},{"name":"Department of Geoscience, Environment and Spatial Planning (DGAOT), Faculty of Sciences, University of Porto, Rua do Campo Alegre, s\/n, 4169-007 Porto, Portugal"}]},{"ORCID":"http:\/\/orcid.org\/0000-0002-5453-3916","authenticated-orcid":false,"given":"Jos\u00e9 C. B.","family":"da Silva","sequence":"additional","affiliation":[{"name":"Department of Geoscience, Environment and Spatial Planning (DGAOT), Faculty of Sciences, University of Porto, Rua do Campo Alegre, s\/n, 4169-007 Porto, Portugal"},{"name":"Instituto de Ci\u00eancias da Terra, Polo Porto, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal"}]},{"ORCID":"http:\/\/orcid.org\/0000-0003-2049-9120","authenticated-orcid":false,"given":"Fanny","family":"Piras","sequence":"additional","affiliation":[{"name":"Collect Localisation Satellites (CLS), 11 rue Herm\u00e8s, Parc Technologique du Canal, 31520 Ramonville St. Agne, France"}]},{"given":"Thomas","family":"Moreau","sequence":"additional","affiliation":[{"name":"Collect Localisation Satellites (CLS), 11 rue Herm\u00e8s, Parc Technologique du Canal, 31520 Ramonville St. Agne, France"}]},{"given":"Samira","family":"Amraoui","sequence":"additional","affiliation":[{"name":"Collect Localisation Satellites (CLS), 11 rue Herm\u00e8s, Parc Technologique du Canal, 31520 Ramonville St. Agne, France"}]},{"given":"Marcello","family":"Passaro","sequence":"additional","affiliation":[{"name":"Deutshes Geod\u00e4tisches Forschungsinstitut der Technischen Universit\u00e4t M\u00fcnchen (DGFI-TUM), Arcisstra\u00dfe 21, 80333 Munich, Germany"}]},{"ORCID":"http:\/\/orcid.org\/0000-0002-4741-3449","authenticated-orcid":false,"given":"Christian","family":"Schwatke","sequence":"additional","affiliation":[{"name":"Deutshes Geod\u00e4tisches Forschungsinstitut der Technischen Universit\u00e4t M\u00fcnchen (DGFI-TUM), Arcisstra\u00dfe 21, 80333 Munich, Germany"}]},{"ORCID":"http:\/\/orcid.org\/0000-0001-9342-0335","authenticated-orcid":false,"given":"Michael","family":"Hart-Davis","sequence":"additional","affiliation":[{"name":"Deutshes Geod\u00e4tisches Forschungsinstitut der Technischen Universit\u00e4t M\u00fcnchen (DGFI-TUM), Arcisstra\u00dfe 21, 80333 Munich, Germany"}]},{"given":"Claire","family":"Maraldi","sequence":"additional","affiliation":[{"name":"Centre National d\u2019\u00c9tudes Spatiales (CNES), 18 avenue Edouard Belin, 31401 Toulouse, France"}]},{"given":"Craig","family":"Donlon","sequence":"additional","affiliation":[{"name":"European Space Agency\/European Space Research and Technology Centre (ESA\/ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1038\/s41597-019-0083-9","article-title":"33 years of globally calibrated wave height and wind speed data based on altimeter observations","volume":"6","author":"Ribal","year":"2019","journal-title":"Sci. Data"},{"key":"ref_2","unstructured":"Frappart, F., Blumstein, D., Cazenave, A., Ramillien, G., Birol, F., Morrow, R., and R\u00e9my, F. (1999). Satellite altimetry: Principles and applications in Earth sciences. Wiley Encyclopedia of Electrical and Electronics Engineering, Wiley."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Stammer, D., and Cazenave, A. (2017). Satellite Altimetry over Oceans and Land Surfaces, CRC Press.","DOI":"10.1201\/9781315151779"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.rse.2014.02.008","article-title":"ALES: A multi-mission adaptive subwaveform retracker for coastal and open ocean altimetry","volume":"145","author":"Passaro","year":"2014","journal-title":"Remote Sens. Environ."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"892","DOI":"10.1016\/j.asr.2020.06.004","article-title":"A RIP-based SAR retracker and its application in North East Atlantic with Sentinel-3","volume":"68","author":"Dinardo","year":"2021","journal-title":"Adv. Space Res."},{"key":"ref_6","unstructured":"Donlon, C., Scharroo, R., Willis, J., Leuliette, E., Bonnefond, P., Picot, N., Schrama, E., and Brown, S. (2019). Sentinel-6A\/B\/Jason-3 Tandem Phase Configurations, European Space Agency. JC-TN-ESA-MI-0876 V2.0."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"112395","DOI":"10.1016\/j.rse.2021.112395","article-title":"The Copernicus Sentinel-6 mission: Enhanced continuity of satellite sea level measurements from space","volume":"258","author":"Donlon","year":"2021","journal-title":"Remote Sens. Environ."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Quartly, G.D., Chen, G., Nencioli, F., Morrow, R., and Picot, N. (2021). An overview of requirements, procedures and current advances in the calibration\/validation of radar altimeters. Remote Sens., 13.","DOI":"10.3390\/rs13010125"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1016\/j.asr.2020.09.037","article-title":"Exploiting the Sentinel-3 tandem phase dataset and azimuth oversampling to better characterize the sensitivity of SAR altimeter sea surface height to long ocean waves","volume":"67","author":"Rieu","year":"2021","journal-title":"Adv. Space Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1109\/TAP.1977.1141536","article-title":"The average impulse response of a rough surface and its applications","volume":"25","author":"Brown","year":"1977","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1109\/TAP.1980.1142398","article-title":"Radar altimeter mean return waveforms from near-normal-incidence ocean surface scattering","volume":"28","author":"Hayne","year":"1980","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"534","DOI":"10.1109\/LGRS.2017.2655621","article-title":"Satellite altimetry observations of large-scale Internal Solitary Waves","volume":"14","author":"Magalhaes","year":"2017","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Santos-Ferreira, A.M., da Silva, J.C.B., and Magalhaes, J.M. (2018). SAR Mode altimetry observations of Internal Solitary Waves in the Tropical Ocean Part 1: Case studies. Remote Sens., 10.","DOI":"10.3390\/rs10040644"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Santos-Ferreira, A.M., da Silva, J.C.B., Magalhaes, J.M., and Srokosz, M. (2019). SAR mode altimetry observations of Internal Solitary Waves in the Tropical Ocean Part 2: A method of detection. Remote Sens., 11.","DOI":"10.3390\/rs11111339"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Santos-Ferreira, A.M., da Silva, J.C.B., Magalhaes, J.M., Amraoui, S., Moreau, T., Maraldi, C., Boy, F., Picot, N., and Borde, F. (2022). Effects of surface wave breaking caused by Internal Solitary Waves in SAR altimeter: Sentinel-3 Copernicus products and advanced new products. Remote Sens., 14.","DOI":"10.3390\/rs14030587"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"166","DOI":"10.5670\/oceanog.2021.203","article-title":"Surface wave breaking caused by Internal Solitary Waves: Effects on radar backscattering measured by SAR and radar altimeter","volume":"34","author":"Magalhaes","year":"2021","journal-title":"Oceanography"},{"key":"ref_17","unstructured":"Gerkema, T., and Zimmerman, J.T.F. (2008). An Introduction to Internal Waves: Lecture Notes, Royal NIOZ."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Yu, C., Meng, J., Sun, L., Zhang, H., and Wang, H. (2022). Study of Sea Surface Geophysical Parameter Changes Due to Internal Solitary Waves Using a Sentinel-3 Synthetic Aperture Radar Altimeter. Remote Sens., 14.","DOI":"10.3390\/rs14215375"},{"key":"ref_19","unstructured":"Dumont, J.-P. (1985). Estimation Optimale des Param\u00e8tres Altim\u00e9triques des Signaux Radar Pos\u00e9idon. [Ph.D. Thesis, University of Toulouse-ENSEEIHT]."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"9927","DOI":"10.1109\/TGRS.2021.3064236","article-title":"Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: Results from simulations and CFOSAT\/SWIM observations","volume":"59","author":"Tourain","year":"2021","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1080\/01490410490465210","article-title":"Improving the Jason-1 ground retracking to better account for attitude effects","volume":"27","author":"Amarouche","year":"2004","journal-title":"Mar. Geod."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"471","DOI":"10.5194\/os-12-471-2016","article-title":"Jason continuity of services: Continuing the Jason altimeter data records as Copernicus Sentinel-6","volume":"12","author":"Scharroo","year":"2016","journal-title":"Ocean Sci."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Thibaut, P., Piras, F., Roinard, H., Guerou, A., Boy, F., Maraldi, C., Bignalet-Cazalet, F., Dibarboure, G., and Picot, N. (2021, January 11\u201316). Benefits of the \u201cAdaptive Retracking Solution\u201d for the JASON-3 GDR-F Reprocessing Campaign. Proceedings of the 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, Brussels, Belgium.","DOI":"10.1109\/IGARSS47720.2021.9553647"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"911","DOI":"10.1109\/TGRS.2014.2330423","article-title":"SAR Altimeter Backscattered Waveform Model","volume":"53","author":"Ray","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","unstructured":"Dinardo, S. (2020). Techniques and Applications for Satellite SAR Altimetry over Water, Land and Ice. [Ph.D. Thesis, Technische Universit\u00e4t Darmstadt]."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1029\/2007JC004220","article-title":"Internal wave detection using the Moderate Resolution Imaging Spectroradiometer (MODIS)","volume":"112","author":"Jackson","year":"2007","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Mitnik, L., and Dubina, V. (2009, January 12\u201317). Non-linear internal waves in the Banda Sea on satellite synthetic aperture radar and visible images. Proceedings of the IEEE International Geoscience and Remote Sensing Symposium, Cape Town, South Africa.","DOI":"10.1109\/IGARSS.2009.5417914"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Hu, B., Meng, J., Sun, L., and Zhang, H. (2021). A Study on Brightness Reversal of Internal Waves in the Celebes Sea Using Himawari-8 Images. Remote Sens., 13.","DOI":"10.3390\/rs13193831"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1038\/nature14399","article-title":"The formation and fate of internal waves in the South China Sea","volume":"521","author":"Alford","year":"2015","journal-title":"Nature"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1038\/314245a0","article-title":"Theory of radar imaging of internal waves","volume":"314","author":"Alpers","year":"1985","journal-title":"Nature"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"8009","DOI":"10.1029\/97JC02724","article-title":"Role of surface films in ERS SAR signatures of internal waves on the shelf: 1. Short-period internal waves","volume":"103","author":"Ermakov","year":"1998","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"24089","DOI":"10.1029\/2000JC900053","article-title":"Role of surface films in ERS SAR signatures of internal waves on the shelf: 3. Mode transitions","volume":"105","author":"Ermakov","year":"2000","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1126\/science.208.4443.451","article-title":"Internal Solitons in the Andaman Sea","volume":"208","author":"Osborne","year":"1980","journal-title":"Science"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"317","DOI":"10.1080\/01490419.2010.491033","article-title":"Relative performance of the MLE3 and MLE4 retracking algorithms on Jason-2 altimeter waveforms","volume":"33","author":"Thibaut","year":"2010","journal-title":"Mar. Geod."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Siegelman, L., Klein, P., Thompson, A.F., Torres, H.S., and Menemenlis, D. (2020). Altimetry-based diagnosis of deep-reaching sub-mesoscale ocean fronts. Fluids, 5.","DOI":"10.3390\/fluids5030145"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Tournadre, J., Chapron, B., Reul, N., and Vandemark, D.C. (2006). A satellite altimeter model for ocean slick detection. J. Geophys. Res. Oceans, 111.","DOI":"10.1029\/2005JC003109"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Picard, B., Picot, N., Dibarboure, G., and Steunou, N. (2021). Characterizing Rain Cells as Measured by a Ka-Band Nadir Radar Altimeter: First Results and Impact on Future Altimetry Missions. Remote Sens., 13.","DOI":"10.20944\/preprints202109.0477.v1"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/2\/392\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,8,24]],"date-time":"2024-08-24T19:51:23Z","timestamp":1724529083000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/2\/392"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,1,8]]},"references-count":37,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2023,1]]}},"alternative-id":["rs15020392"],"URL":"https:\/\/doi.org\/10.3390\/rs15020392","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2023,1,8]]}}}