This study presents a first assessment of the Top-Of-Atmosphere (TOA) radiances measured in the visible and near-infrared (VNIR) wavelengths from PRISMA (PRecursore IperSpettrale della Missione Applicativa), the new hyperspectral satellite sensor of the Italian Space Agency in orbit since March 2019. In particular, the radiometrically calibrated PRISMA Level 1 TOA radiances were compared to the TOA radiances simulated with a radiative transfer code, starting from in situ measurements of water reflectance. In situ data were obtained from a set of fixed position autonomous radiometers covering a wide range of water types, encompassing coastal and inland waters. A total of nine match-ups between PRISMA and in situ measurements distributed from July 2019 to June 2020 were analysed. Recognising the role of Sentinel-2 for inland and coastal waters applications, the TOA radiances measured from concurrent Sentinel-2 observations were added to the comparison. The results overall demonstrated that PRISMA VNIR sensor is providing TOA radiances with the same magnitude and shape of those in situ simulated (spectral angle difference, SA, between 0.80 and 3.39; root mean square difference, RMSD, between 0.98 and 4.76 [mW m−2 sr−1 nm−1]), with slightly larger differences at shorter wavelengths. The PRISMA TOA radiances were also found very similar to Sentinel-2 data (RMSD 3.78 [mW m−2 sr−1 nm−1]), and encourage a synergic use of both sensors for aquatic applications. Further analyses with a higher number of match-ups between PRISMA, in situ and Sentinel-2 data are however recommended to fully characterize the on-orbit calibration of PRISMA for its exploitation in aquatic ecosystem mapping.
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ecodam EXT contributors
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ecodamEXT
The aim of the Life On Trees (LOT) program is to generate baseline knowledge about the number of eukaryotic species a single large aged tropical tree can host and to understand how these communities of organisms are assembled. The program is conducted in the Amazon and Andes biodiversity hotspots. Our first project, LOT-Amazon 2022, was performed on a spectacular Dussia tree (Fabaceae), which was 50 m high and 45 m wide. The sampling was carried out by professional climbers, guided by experts of the different eukaryotic groups studied (plants, fungi, animals, protists). To better understand the contribution of different tree components (bark, leaves, fruits, flowers, living and dead wood) to overall tree biodiversity, we assigned observations into communities based on height zone or microhabitat and will examine similarities and nestedness in the composition of these communities. The first results show that a single tree can host a tremendous diversity (e.g., 42 orchids, 28 ferns, and more than 200 bryophytes, 180 lichen species identified, which are world records considering the 400m elevation). This confirms that large old tropical trees are important pools of biodiversity probably in relation with the variety of local microhabitats and tree age. Funding: Fonds de Dotation Biotope pour la Nature Web and/or Twitter account: www.lifeontrees.org
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RBINS Staff Publications 2023
