{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,3]],"date-time":"2025-12-03T17:51:07Z","timestamp":1764784267505,"version":"build-2065373602"},"reference-count":31,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2019,7,11]],"date-time":"2019-07-11T00:00:00Z","timestamp":1562803200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["SFRH\/BPD\/86498\/2012","SFRH\/BSAB\/143164\/2019","UID\/GEO\/04683\/2013","PTDC\/CTAMET\/ 29678\/2017"],"award-info":[{"award-number":["SFRH\/BPD\/86498\/2012","SFRH\/BSAB\/143164\/2019","UID\/GEO\/04683\/2013","PTDC\/CTAMET\/ 29678\/2017"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100010661","name":"Horizon 2020 Framework Programme","doi-asserted-by":"publisher","award":["0753_CILIFO_5_E","ALT20-03-0145-FEDER- 000004","ALT20-03-0145-FEDER-000011"],"award-info":[{"award-number":["0753_CILIFO_5_E","ALT20-03-0145-FEDER- 000004","ALT20-03-0145-FEDER-000011"]}],"id":[{"id":"10.13039\/100010661","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>This study presents a validation of aerosol optical thickness (AOT) and integrated water vapour (IWV) products provided by the European Space Agency (ESA) from multi-spectral imager (MSI) measurements on board the Sentinel-2 satellite (ESA-L2A). For that purpose, data from 94 Aerosol Robotic Network (AERONET) stations over Europe and adjacent regions, covering a wide geographical region with a variety of climate and environmental conditions and during the period between March 2017 and December 2018 have been used. The comparison between ESA-L2A and AERONET shows a better agreement for IWV than the AOT, with normalized root mean square errors (NRMSE) of 5.33% and 9.04%, respectively. This conclusion is also reflected in the values of R2, which are 0.99 and 0.65 for IWV and AOT, respectively. The study period was divided into two sub-periods, before and after 15 January 2018, when the Sentinel-2A spectral response functions of bands 1 and 2 (centered at 443 and 492 nm) were updated by ESA, in order to investigate if the lack of agreement in the AOT values was connected to the use of incorrect spectral response functions. The comparison of ESA-L2A AOT with AERONET measurements showed a better agreement for the second sub-period, with root mean square error (RMSE) values of 0.08 in comparison with 0.14 in the first sub-period. This same conclusion was attained considering mean bias error (MBE) values that decreased from 0.09 to 0.01. The ESA-L2A AOT values estimated with the new spectral response functions were closer to the correspondent reference AERONET values than the ones obtained using the previous spectral response functions. IWV was not affected by this change since the retrieval algorithm does not use bands 1 and 2 of Sentinel-2. Additionally, an analysis of potential uncertainty sources to several factors affecting the AOT comparison is presented and recommendations regarding the use of ESA-L2A AOT dataset are given.<\/jats:p>","DOI":"10.3390\/rs11141649","type":"journal-article","created":{"date-parts":[[2019,7,11]],"date-time":"2019-07-11T11:28:28Z","timestamp":1562844508000},"page":"1649","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":25,"title":["Validation of ESA Sentinel-2 L2A Aerosol Optical Thickness and Columnar Water Vapour during 2017\u20132018"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4645-5014","authenticated-orcid":false,"given":"Mar\u00eda \u00c1ngeles","family":"Obreg\u00f3n","sequence":"first","affiliation":[{"name":"Department of Physics, Institute of Earth Sciences, Institute for Advanced Studies and Research, University of \u00c9vora, 7000-671 \u00c9vora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2273-7647","authenticated-orcid":false,"given":"Gon\u00e7alo","family":"Rodrigues","sequence":"additional","affiliation":[{"name":"Department of Physics, Institute of Earth Sciences, Institute for Advanced Studies and Research, University of \u00c9vora, 7000-671 \u00c9vora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2981-2232","authenticated-orcid":false,"given":"Maria Joao","family":"Costa","sequence":"additional","affiliation":[{"name":"Department of Physics, Institute of Earth Sciences, School of Science and Technology, University of \u00c9vora, 7000-671 \u00c9vora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8912-5277","authenticated-orcid":false,"given":"Miguel","family":"Potes","sequence":"additional","affiliation":[{"name":"Department of Physics, Institute of Earth Sciences, Institute for Advanced Studies and Research, University of \u00c9vora, 7000-671 \u00c9vora, Portugal"}]},{"given":"Ana Maria","family":"Silva","sequence":"additional","affiliation":[{"name":"Department of Physics, Institute of Earth Sciences, Institute for Advanced Studies and Research, University of \u00c9vora, 7000-671 \u00c9vora, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"252","DOI":"10.1016\/j.atmosres.2018.06.001","article-title":"Impact of aerosol and water vapour on SW radiation at the surface: Sensitivity study and applications","volume":"213","author":"Costa","year":"2018","journal-title":"Atmos. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"13195","DOI":"10.5194\/acp-15-13195-2015","article-title":"On the ability of RegCM4 regional climate model to simulate surface solar radiation patterns over Europe: An assessment using satellite-based observations","volume":"15","author":"Alexandri","year":"2015","journal-title":"Atmos. Chem. Phys."},{"key":"ref_3","unstructured":"Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M., and Miller, H.L. (2007). Changes in atmospheric constituents and in radiative forcing. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Gascon, F., Bouzinac, C., Th\u00e9paut, O., Jung, M., Francesconi, B., Louis, J., Lonjou, V., Lafrance, B., Massera, S., and Gaudel-Vacaresse, A. (2017). Copernicus sentinel-2 calibration and products validation status. Remote Sens., 9.","DOI":"10.3390\/rs9060584"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1617","DOI":"10.1029\/2001GL013205","article-title":"Validation of MODIS aerosol optical depth retrieval over land","volume":"29","author":"Chu","year":"2002","journal-title":"Geophys. Res. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"D10S04","DOI":"10.1029\/2004JD004706","article-title":"Multiangle Imaging Spectroradiometer (MISR) global aerosol optical depth validation based on 2 years of coincident Aerosol Robotic Network (AERONET) observations","volume":"110","author":"Kahn","year":"2005","journal-title":"J. Geophys. Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2989","DOI":"10.5194\/amt-6-2989-2013","article-title":"The Collection 6 MODIS aerosol products over land and ocean","volume":"6","author":"Levy","year":"2013","journal-title":"Atmos. Meas. Tech."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"D05107","DOI":"10.1029\/2008JD011230","article-title":"Validation of MODIS Terra, AIRS, NCEP\/DOE AMIP-II Reanalysis-2, and AERONET Sun photometer derived integrated precipitable water vapor using ground-based GPS receivers over India","volume":"114","author":"Prasad","year":"2009","journal-title":"J. Geophys. Res."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.atmosenv.2015.04.013","article-title":"Intercomparison of MODIS, MISR, OMI, and CALIPSO aerosol optical depth retrievals for four locations on the Indo-Gangetic plains and validation against AERONET data","volume":"111","author":"Bibi","year":"2015","journal-title":"Atmos. Environ."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1002\/2014JD022453","article-title":"MODIS Collection 6 aerosol products: Comparison between Aqua\u2019s e-Deep Blue, Dark Target, and merged data sets, and usage recommendations","volume":"119","author":"Sayer","year":"2014","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_11","unstructured":"Pflug, B., Main-Knorn, M., Bieniarz, J., Debaecker, V., and Louis, J. (2016, January 9\u201313). Early Validation of Sentinel-2 L2A Processor and Products. Proceedings of the Living Planet Symposium 2016, Prague, Czech Republic. ESA SP-740."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Doxani, G., Vermote, E., Roger, J.C., Gascon, F., Adriaensen, S., Frantz, D., Hagolle, O., Hollstein, A., Kirches, G., and Li, F. (2018). Atmospheric Correction Inter-Comparison Exercise. Remote Sens., 10.","DOI":"10.3390\/rs10020352"},{"key":"ref_13","unstructured":"Mueller-Wilm, U., Devignot, O., and Pessiot, L. (2017, December 01). Sen2Cor Configuration and User Manual. S2-PDGS-MPC-L2A-SUM-V2.4. Available online: http:\/\/step.esa.int\/thirdparties\/sen2cor\/2.4.0\/Sen2Cor_240_Documenation_PDF\/S2-PDGS-MPC-L2A-SUM-V2.4.0.pdf."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Djamai, N., and Fernandes, R. (2018). Comparison of SNAP-Derived Sentinel-2A L2A Product to ESA Product over Europe. Remote Sens., 10.","DOI":"10.3390\/rs10060926"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"919","DOI":"10.1080\/01431161.2012.716173","article-title":"Remote sensing of aerosols in urban areas from very high spatial resolution images: Application of the OSIS code to multispectral PELICAN airborne data","volume":"34","author":"Thomas","year":"2013","journal-title":"Int. J. Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1360","DOI":"10.1080\/10473289.2004.10471005","article-title":"Recommendations on the Use of Satellite Remote-Sensing Data for Urban Air Quality","volume":"54","author":"Hoff","year":"2004","journal-title":"J. Air Waste Manag. Assoc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.rse.2011.11.026","article-title":"Sentinel-2: ESA\u2019s Optical High-Resolution Mission for GMES Operational Services","volume":"20","author":"Drusch","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_18","unstructured":"Richter, R., Louis, J., and M\u00fcller-Wilm, U. (2012). Sentinel-2 MSI\u2014Level 2A Products Algorithm Theoretical Basis Document, Telespazio VEGA Deutschland GmbH. S2PAD-ATBD-0001, Issue 2.0."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1357","DOI":"10.1080\/01431168808954942","article-title":"Algorithm for automatic atmospheric corrections to visible and near-IR satellite imagery","volume":"9","author":"Kaufman","year":"1988","journal-title":"Int. J. Remote Sens."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"353","DOI":"10.1016\/S0034-4257(98)00044-3","article-title":"Atmospheric precorrected differential absorption technique to retrieve columnar water vapour","volume":"65","author":"Borel","year":"1998","journal-title":"Remote Sens. Environ."},{"key":"ref_21","unstructured":"Clerc, S., and MPC Team (2018). Level 2A Data Quality Report (Ref. S2-PDGS-MPC-L2ADQR), European Space Agency."},{"key":"ref_22","unstructured":"Louis, J., Debaecker, V., Pflug, B., Main-Knorn, M., Bieniarz, J., Mueller-Wilm, U., Cadau, E., and Gascon, F. (2016, January 9\u201313). Sentinel-2 Sen2Cor: L2A processor for users. Proceedings of the Living Planet Symposium 2016, Prague, Czech Republic. ESA SP-740."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0034-4257(98)00031-5","article-title":"AERONET\u2014A federated instrument network and data archive for aerosol characterization","volume":"66","author":"Holben","year":"1998","journal-title":"Remote Sens. Environ."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1016\/S0034-4257(00)00109-7","article-title":"Cloud screening and quality control algorithms for the AERONET data base","volume":"73","author":"Smirnov","year":"2000","journal-title":"Remote Sens. Environ."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Bilal, M., Qiu, Z., Shen, X., and Nazeer, M. (2018). A New MODIS C6 Dark Target and Deep Blue Merged Aerosol Product on a 3 km Spatial Grid. Remote Sens., 10.","DOI":"10.3390\/rs10030463"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"D21202","DOI":"10.1029\/2005JD005986","article-title":"Forest fire aerosol over the Mediterranean basin during summer 2003","volume":"110","author":"Pace","year":"2005","journal-title":"J. Geophys. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2509","DOI":"10.4209\/aaqr.2017.05.0159","article-title":"Thirteen years of aerosol radiative forcing in Southwestern Iberian Peninsula","volume":"17","author":"Costa","year":"2017","journal-title":"Aerosol Air Qual. Res."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2367","DOI":"10.5194\/acp-4-2367-2004","article-title":"Aerosol seasonal variability over the Mediterranean region and relative impact of maritime, continental and Saharan dust particles over the basin from MODIS data in the year 2001","volume":"4","author":"Barnaba","year":"2004","journal-title":"Atmos. Chem. Phys."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"7315","DOI":"10.1016\/j.atmosenv.2007.05.017","article-title":"Aerosol climatology and discrimination of different types over Athens, Greece, based on MODIS data","volume":"41","author":"Kaskaoutis","year":"2007","journal-title":"Atmos. Environ."},{"key":"ref_30","first-page":"1","article-title":"Regional differences of column aerosol parameters in western Iberian Peninsula","volume":"12","author":"Pereira","year":"2012","journal-title":"Atmos. Environ."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2005JD006610","article-title":"Aerosol extinction in a remote continental region of the Iberian Peninsula during summer","volume":"111","author":"Elias","year":"2006","journal-title":"J. Geophys. Res."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/14\/1649\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:04:34Z","timestamp":1760187874000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/14\/1649"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,7,11]]},"references-count":31,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2019,7]]}},"alternative-id":["rs11141649"],"URL":"https:\/\/doi.org\/10.3390\/rs11141649","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2019,7,11]]}}}