{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,3]],"date-time":"2025-12-03T17:47:50Z","timestamp":1764784070161,"version":"build-2065373602"},"reference-count":51,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2018,3,20]],"date-time":"2018-03-20T00:00:00Z","timestamp":1521504000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Launched on 16 February 2016, Sentinel-3A (S3A) carries a two-band microwave radiometer (MWR) similar to that of Envisat, and is aimed at the precise retrieval of the wet tropospheric correction (WTC) through collocated measurements using the Synthetic Aperture Radar Altimeter (SRAL) instrument. This study aims at presenting an independent assessment of the WTC derived from the S3A MWR over the open and coastal ocean. Comparisons with other four MWRs show Root Mean Square (RMS) differences (cm) of S3A with respect to these sensors of 1.0 (Global Precipitation Measurement (GPM) Microwave Imager, GMI), 1.2 (Jason-2), 1.3 (Jason-3), and 1.5 (Satellite with ARgos and ALtika (SARAL)). The linear fit with respect to these MWR shows scale factors close to 1 and small offsets, indicating a good agreement between all these sensors. In spite of the short analysis period of 10 months, a stable temporal evolution of the S3A WTC has been observed. In line with the similar two-band instruments aboard previous European Space Agency (ESA) altimetric missions, strong ice and land contamination can be observed, the latter mainly found up to 20\u201325 km from the coast. Comparisons with the European Centre for Medium-Range Weather Forecasts (ECMWF) and an independent WTC derived only from third party data are also shown, indicating good overall performance. However, improvements in both the retrieval algorithm and screening of invalid MWR observations are desirable to achieve the quality of the equivalent WTC from Jason-3. The outcome of this study is a deeper knowledge of the measurement capabilities and limitations of the type of MWR aboard S3A and of the present WTC retrieval algorithms.<\/jats:p>","DOI":"10.3390\/rs10030484","type":"journal-article","created":{"date-parts":[[2018,3,20]],"date-time":"2018-03-20T15:59:39Z","timestamp":1521561579000},"page":"484","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":31,"title":["Independent Assessment of Sentinel-3A Wet Tropospheric Correction over the Open and Coastal Ocean"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0946-0092","authenticated-orcid":false,"given":"Maria","family":"Fernandes","sequence":"first","affiliation":[{"name":"Faculdade de Ci\u00eancias, Universidade do Porto, 4169-007 Porto, Portugal"},{"name":"Centro Interdisciplinar de Investiga\u00e7\u00e3o Marinha e Ambiental (CIIMAR\/CIMAR), Universidade do Porto, 4050-123 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8849-7546","authenticated-orcid":false,"given":"Clara","family":"L\u00e1zaro","sequence":"additional","affiliation":[{"name":"Faculdade de Ci\u00eancias, Universidade do Porto, 4169-007 Porto, Portugal"},{"name":"Centro Interdisciplinar de Investiga\u00e7\u00e3o Marinha e Ambiental (CIIMAR\/CIMAR), Universidade do Porto, 4050-123 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2018,3,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Vignudelli, S., Kostianoy, A., Cipollini, P., and Benvensite, J. (2011). Radar altimetry: Past, present and future. Coastal Altimetry, Springer.","DOI":"10.1007\/978-3-642-12796-0"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Stammer, D., and Cazenave, A. (2017). Satellite Altimetry over Oceans and Land Surfaces, CRC Press. [1st ed.].","DOI":"10.1201\/9781315151779"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"901","DOI":"10.5194\/os-9-901-2013","article-title":"From satellite altimetry to argo and operational oceanography: Three revolutions in oceanography","volume":"9","year":"2013","journal-title":"Ocean Sci."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Stammer, D., and Cazenave, A. (2017). Use of satellite altimetry for operational oceanography. Satellite Altimetry over Oceans and Land Surfaces, CRC Press.","DOI":"10.1201\/9781315151779"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"67","DOI":"10.5194\/os-11-67-2015","article-title":"Improved sea level record over the satellite altimetry ERA (1993\u20132010) from the climate change initiative project","volume":"11","author":"Ablain","year":"2015","journal-title":"Ocean Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1007\/s10712-016-9389-8","article-title":"Satellite altimetry-based sea level at global and regional scales","volume":"38","author":"Ablain","year":"2017","journal-title":"Surv. Geophys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"557","DOI":"10.5194\/essd-9-557-2017","article-title":"A new phase in the production of quality-controlled sea level data","volume":"9","author":"Quartly","year":"2017","journal-title":"Earth Syst. Sci. Data"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Stammer, D., and Cazenave, A. (2017). A 25-year satellite altimetry-based global mean sea level record: Closure of the sea level budget and missing components. Satellite Altimetry over Oceans and Land Surfaces, CRC Press.","DOI":"10.1201\/9781315151779"},{"key":"ref_9","first-page":"1","article-title":"An accurate and homogeneous altimeter sea level record from the esa climate change initiative","volume":"2017","author":"Legeais","year":"2017","journal-title":"Earth Syst. Sci. Data"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Vignudelli, S., Kostianoy, A.G., and Cipollini, P.J.B. (2011). From research to operations: The usda global reservoir and lake monitor. Coastal Altimetry, Springer-Verlag.","DOI":"10.1007\/978-3-642-12796-0"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Cretaux, J.-F., Nielsen, K., Frappart, F., Papa, F., Calmant, S., and Benveniste, J. (2017). Hydrological applications of satellite altimetry: Rivers, lakes, man-made reservoirs, inundated areas. Satellite Altimetry in Coastal Regions, CRC Press.","DOI":"10.1201\/9781315151779-14"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Stammer, D., and Cazenave, A. (2017). Applications of satellite altimetry to study the antarctic ice sheet, satellite altimetry in coastal regions. Satellite Altimetry over Oceans and Land Surfaces, CRC Press. [1st ed.].","DOI":"10.1201\/9781315151779"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"4952","DOI":"10.3390\/rs6064952","article-title":"Atmospheric corrections for altimetry studies over inland water","volume":"6","author":"Fernandes","year":"2014","journal-title":"Remote Sens."},{"key":"ref_14","unstructured":"Fu, L.L., and Cazenave, A. (2001). Satellite altimetry. Satellite Altimetry and Earth Sciences: A Handbook of Techniques and Applications, Academic Press."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Vieira, T., Fernandes, M.J., and L\u00e1zaro, C. (2017). Analysis and retrieval of tropospheric corrections for cryosat-2 over inland waters. Adv. Sp. Res., 46.","DOI":"10.1016\/j.asr.2017.09.002"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Stammer, D., and Cazenave, A. (2017). Satellite altimetry in coastal regions. Satellite Altimetry over Oceans and Land Surfaces, CRC Press. [1st ed.].","DOI":"10.1201\/9781315151779"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1109\/36.368213","article-title":"Topex\/poseidon microwave radiometer (TMR). III. Wet troposphere range correction algorithm and pre-launch error budget","volume":"33","author":"Keihm","year":"1995","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_18","unstructured":"Eymard, L., and Obligis, E. (2006, January 13\u201318). The Altimetric Wet Troposheric Correction: Progress Since the ERS-1 Mission. Proceedings of the15 Years of Progress in Radar Altimetry, Venice, Italy."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1806","DOI":"10.1109\/TGRS.2008.2010130","article-title":"Cloud and rain effects on altika\/saral ka-band radar altimeter-part i: Modeling and mean annual data availability","volume":"47","author":"Tournadre","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_20","unstructured":"Sentinel-3 Team (2013). Sentinel-3 User Handbook, European Space Agency. [2nd ed.]. GMES-S3OP-EOPG-TN-13-0001."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Dinardo, S., Fenoglio-Marc, L., Buchhaupt, C., Becker, M., Scharroo, R., Joana Fernandes, M., and Benveniste, J. (2017). Coastal sar and plrm altimetry in german bight and west baltic sea. Adv. Sp. Res.","DOI":"10.1016\/j.asr.2017.12.018"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1131","DOI":"10.1175\/JTECH1897.1","article-title":"Improved level-3 oceanic rainfall retrieval from dual-frequency spaceborne radar altimeter systems","volume":"23","author":"Tournadre","year":"2006","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1016\/j.rse.2015.07.023","article-title":"Improved wet path delays for all esa and reference altimetric missions","volume":"169","author":"Fernandes","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Fernandes, M.J., and Lazaro, C. (2016). Gpd+ wet tropospheric corrections for cryosat-2 and gfo altimetry missions. Remote Sens., 8.","DOI":"10.3390\/rs8100851"},{"key":"ref_25","unstructured":"(2017, August 31). EUMETSAT, S3a STM Reprocessing\u2014\u201cSpring 2017\u201d (Level 0 to Level 2). Available online: eum\/ops-sen3\/rep\/17\/940906."},{"key":"ref_26","unstructured":"(2017, September 15). EUMETSAT, Sentinel-3a Product Notice\u2014STM l2 Marine (\u201cSpring Reprocessing Campaign\u201d). Available online: um\/ops-sen3\/doc\/17\/944329."},{"key":"ref_27","unstructured":"Scharroo, R., Leuliette, E., Naeije, M., Martin-Puig, C., and Pires, N. (2016, January 9\u201313). Rads Version 4: An efficient way to analyse the Multi-Mission altimeter database. Proceedings of the ESA Living Planet Symposium, Prague, Czech Republic."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"802","DOI":"10.1175\/JTECH1878.1","article-title":"First three years of the microwave radiometer aboard envisat: In-flight calibration, processing, and validation of the geophysical products","volume":"23","author":"Obligis","year":"2006","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"4302","DOI":"10.1109\/JSTARS.2015.2442416","article-title":"Comparison of regression algorithms for the retrieval of the wet tropospheric path","volume":"8","author":"Thao","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_30","unstructured":"Collecte Localisation Satellites (CLS) (2011). Surface Topography Mission (STM) Sral\/Mwr L2 Algorithms Definition, Accuracy and Specification, CLS. S3PAD-RS-CLS-SD03-00017."},{"key":"ref_31","unstructured":"Mercier, F., Rosmorduc, V., Carr\u00e8re, L., and Thibaut, P. (2018, March 19). Coastal and Hydrology Altimetry Product (PISTACH) Handbook. Available online: https:\/\/www.aviso.altimetry.fr\/fileadmin\/documents\/data\/tools\/hdbk_Pistach.pdf."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Meissner, T., Wentz, F.J., and Draper, D. (2012). Gmi Calibration Algorithm and Analysis Theoretical Basis Document, Remote Sensing Systems. Report Number 041912.","DOI":"10.56236\/RSS-au"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"3452","DOI":"10.1109\/JSTARS.2015.2403303","article-title":"The global precipitation measurement (GPM) microwave imager (GMI): Instrument overview and early on-orbit performance","volume":"8","author":"Draper","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"4977","DOI":"10.3390\/rs5104977","article-title":"Analysis and inter-calibration of wet path delay datasets to compute the wet tropospheric correction for cryosat-2 over ocean","volume":"5","author":"Fernandes","year":"2013","journal-title":"Remote Sens."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3211","DOI":"10.1109\/TGRS.2011.2104967","article-title":"Using objective analysis of scanning radiometer measurements to compute the water vapor path delay for altimetry","volume":"49","author":"Stum","year":"2011","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"8703","DOI":"10.1029\/96JC01751","article-title":"A well-calibrated ocean algorithm for special sensor microwave\/imager","volume":"102","author":"Wentz","year":"1997","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Wentz, F.J. (2013). SSM\/I Version-7 Calibration Report, Remote Sensing Systems. RSS Technical Report 011012.","DOI":"10.56236\/RSS-av"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1986","DOI":"10.1109\/TGRS.2009.2037220","article-title":"A novel near-land radiometer wet path-delay retrieval algorithm: Application to the Jason-2\/OSTM advanced microwave radiometer","volume":"48","author":"Brown","year":"2010","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_39","unstructured":"Dumont, J.P., Rosmorduc, V., Picot, N., Bronner, E., Desai, S., Bonekamp, H., Figa, J., Lillibridge, J., and Scharroo, R. (2018, March 19). OSTM\/Jason-2 Products Handbook, Available online: http:\/\/www.ospo.noaa.gov\/Products\/documents\/J2_handbook_v1-8_no_rev.pdf."},{"key":"ref_40","unstructured":"Dumont, J.P., Rosmorduc, V., Carrere, L., Picot, N., Bronner, E., Couhert, A., Guillot, A., Desai, S., Bonekamp, H., and Figa, J. (2018, March 19). Jason-3 Products Handbook. Available online: https:\/\/www.aviso.altimetry.fr\/fileadmin\/documents\/data\/tools\/hdbk_j3.pdf."},{"key":"ref_41","unstructured":"Brown, S., and Islam, T. (2017, January 23\u201327). Jason-3 GDR calibration stability enabled by the cold sky maneuvers. Proceedings of the Ocean Surface Topography Science Team Meeting, Miami, FL, USA."},{"key":"ref_42","unstructured":"Bronner, E., Guillot, A., and Picot, N. (2018, March 19). SARAL\/Altika Products Handbook. Available online: https:\/\/www.aviso.altimetry.fr\/fileadmin\/documents\/data\/tools\/SARAL_Altika_products_handbook.pdf."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Vieira, T., Fernandes, M.J., and L\u00e1zaro, C. (2018). Independent assessment of on-board microwave radiometer measurements in coastal zones using tropospheric delays from gnss. IEEE Trans. Geosci. Remote Sens., under review.","DOI":"10.1109\/TGRS.2018.2869258"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1593","DOI":"10.1029\/RS020i006p01593","article-title":"Geodesy by radio interferometry\u2014Effects of atmospheric modeling errors on estimates of baseline length","volume":"20","author":"Davis","year":"1985","journal-title":"Radio Sci."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1007\/s00190-007-0170-0","article-title":"Implementation and testing of the gridded vienna mapping function 1 (VMF1)","volume":"82","author":"Kouba","year":"2008","journal-title":"J. Geod."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1352","DOI":"10.1016\/j.asr.2012.04.025","article-title":"Tropospheric delays from gnss for application in coastal altimetry","volume":"51","author":"Fernandes","year":"2013","journal-title":"Adv. Space Res."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1002\/qj.828","article-title":"The era-interim reanalysis: Configuration and performance of the data assimilation system","volume":"137","author":"Dee","year":"2011","journal-title":"Q. J. R. Meteorol. Soc."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1109\/LGRS.2010.2042425","article-title":"Gnss-derived path delay: An approach to compute the wet tropospheric correction for coastal altimetry","volume":"7","author":"Fernandes","year":"2010","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_49","first-page":"10","article-title":"Increased resolution in the ecmwf deterministic and ensemble prediction systems","volume":"Volume 124","author":"Miller","year":"2010","journal-title":"ECMWF Newsletter"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1881","DOI":"10.1175\/JTECH-D-13-00157.1","article-title":"Trend and variability of the atmospheric water vapor: A mean sea level issue","volume":"31","author":"Thao","year":"2014","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_51","unstructured":"(2018, February 20). eoPortal:Satellite Missions Directory, Copernicus: Sentinel-6\/Jason-CS (Jason Continuity of Service) Mission. Available online: https:\/\/directory.eoportal.org\/web\/eoportal\/satellite-missions\/content\/-\/article\/jason-cs."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/3\/484\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:57:50Z","timestamp":1760194670000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/3\/484"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,3,20]]},"references-count":51,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2018,3]]}},"alternative-id":["rs10030484"],"URL":"https:\/\/doi.org\/10.3390\/rs10030484","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2018,3,20]]}}}