{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:14:36Z","timestamp":1760235276504,"version":"build-2065373602"},"reference-count":24,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2021,8,4]],"date-time":"2021-08-04T00:00:00Z","timestamp":1628035200000},"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>This paper presents an innovative method for observing vegetation health at a very high spatial resolution (~5 \u00d7 5 cm) and low cost by upgrading an existing Aerosol RObotic NETwork (AERONET) ground station dedicated to the observation of aerosols in the atmosphere. This study evaluates the capability of a sun\/sky photometer to perform additional surface reflectance observations. The ground station of Toulouse, France, which belongs to the AERONET sun\/sky photometer network, is used for this feasibility study. The experiment was conducted for a 5-year period (between 2016 and 2020). The sun\/sky photometer was mounted on a metallic structure at a height of 2.5 m, and the acquisition software was adapted to add a periodical (every hour) ground-observation scenario with the sun\/sky photometer observing the surface instead of being inactive. Evaluation is performed by using a classical metric characterizing the vegetation health: the normalized difference vegetation index (NDVI), using as reference the satellite NDVI derived from a Sentinel-2 (S2) sensor at 10 \u00d7 10 m resolution. Comparison for the 5-year period showed good agreement between the S2 and sun\/sky photometer NDVIs (i.e., bias = 0.004, RMSD = 0.082, and R = 0.882 for a mean value of S2A NDVI around 0.6). Discrepancies could have been due to spatial-representativeness issues (of the ground measurement compared to S2), the differences between spectral bands, and the quality of the atmospheric correction applied on S2 data (accuracy of the sun\/sky photometer instrument was better than 0.1%). However, the accuracy of the atmospheric correction applied on S2 data in this station appeared to be of good quality, and no dependence on the presence of aerosols was observed. This first analysis of the potential of the CIMEL CE318 sun\/sky photometer to monitor the surface is encouraging. Further analyses need to be carried out to estimate the potential in different AERONET stations. The occasional rerouting of AERONET stations could lead to a complementary network of surface reflectance observations. This would require an update of the software, and eventual adaptations of the measurement platforms to the station environments. The additional cost, based on the existing AERONET network, would be quite limited. These new surface measurements would be interesting for measurements of vegetation health (monitoring of NDVI, and also of other vegetation indices such as the leaf area and chlorophyll indices), for validation and calibration exercise purposes, and possibly to refine various scientific algorithms (i.e., algorithms dedicated to cloud detection or the AERONET aerosol retrieval algorithm itself). CIMEL is ready to include the ground scenario used in this study in all new sun\/sky photometers.<\/jats:p>","DOI":"10.3390\/rs13163072","type":"journal-article","created":{"date-parts":[[2021,8,4]],"date-time":"2021-08-04T21:45:06Z","timestamp":1628113506000},"page":"3072","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Casual Rerouting of AERONET Sun\/Sky Photometers: Toward a New Network of Ground Measurements Dedicated to the Monitoring of Surface Properties?"],"prefix":"10.3390","volume":"13","author":[{"given":"Dominique","family":"Carrer","sequence":"first","affiliation":[{"name":"Centre National de Recherches M\u00e9t\u00e9orologiques (CNRM), Universit\u00e9 de Toulouse, M\u00e9t\u00e9o France, CNRS, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France"}]},{"given":"Catherine","family":"Meurey","sequence":"additional","affiliation":[{"name":"Centre National de Recherches M\u00e9t\u00e9orologiques (CNRM), Universit\u00e9 de Toulouse, M\u00e9t\u00e9o France, CNRS, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2358-0493","authenticated-orcid":false,"given":"Olivier","family":"Hagolle","sequence":"additional","affiliation":[{"name":"CESBIO, UMR 5126. 18 Avenue Edouard Belin, bpi 2801, CEDEX 9, 31401 Toulouse, France"}]},{"given":"Guillaume","family":"Bigeard","sequence":"additional","affiliation":[{"name":"Centre National de Recherches M\u00e9t\u00e9orologiques (CNRM), Universit\u00e9 de Toulouse, M\u00e9t\u00e9o France, CNRS, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7917-8711","authenticated-orcid":false,"given":"Alexandre","family":"Paci","sequence":"additional","affiliation":[{"name":"Centre National de Recherches M\u00e9t\u00e9orologiques (CNRM), Universit\u00e9 de Toulouse, M\u00e9t\u00e9o France, CNRS, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France"}]},{"given":"Jean-Marie","family":"Donier","sequence":"additional","affiliation":[{"name":"Centre National de Recherches M\u00e9t\u00e9orologiques (CNRM), Universit\u00e9 de Toulouse, M\u00e9t\u00e9o France, CNRS, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France"}]},{"given":"Gilles","family":"Bergametti","sequence":"additional","affiliation":[{"name":"Laboratoire Interuniversitaire des Syst\u00e8mes Atmosph\u00e9riques (LISA), UMR CNRS 7583, Universit\u00e9 de Paris and Universit\u00e9 Paris Est, IPSL, 94010 Creteil, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7704-5974","authenticated-orcid":false,"given":"Thierry","family":"Bergot","sequence":"additional","affiliation":[{"name":"Centre National de Recherches M\u00e9t\u00e9orologiques (CNRM), Universit\u00e9 de Toulouse, M\u00e9t\u00e9o France, CNRS, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6425-6492","authenticated-orcid":false,"given":"Jean-Christophe","family":"Calvet","sequence":"additional","affiliation":[{"name":"Centre National de Recherches M\u00e9t\u00e9orologiques (CNRM), Universit\u00e9 de Toulouse, M\u00e9t\u00e9o France, CNRS, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France"}]},{"given":"Philippe","family":"Goloub","sequence":"additional","affiliation":[{"name":"LOA, Laboratoire d\u2019Optique Atmosph\u00e9rique-UMR 8518, 59000 Lille, France"}]},{"given":"St\u00e9phane","family":"Victori","sequence":"additional","affiliation":[{"name":"CIMEL ELECTRONIQUE, Laboratoire Charles Fabry, 75001 Paris, France"}]},{"given":"Zhuosen","family":"Wang","sequence":"additional","affiliation":[{"name":"NASA, Goddard Space Flight Center (GSFC), Greenbelt, MD 20771, USA"},{"name":"Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742, USA"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0034-4257(98)00031-5","article-title":"AERONET: A federated instrument network and data archive for aerosol characterization","volume":"66","author":"Holben","year":"1998","journal-title":"Remote Sens. 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