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- 3e785f3e30239bbd2c572db9fe564e8b82707895 description "The autonomous hyperspectral systems perform automated measurements every 15 a 30 minutes during daylight. Total upwelling radiance (at 40° nadir viewing angle), downwelling radiance (at 140° nadir viewing angle) and downwelling irradiance (at 180° nadir viewing angle) are measured at given relative azimuth to the sun (90°, 135°, 225° and/or 270° as a function of the sun azimuth, instrument location and platform shading of the water target) for the computation of the water leaving radiance and reflectance (see Vansteenwegen et al., Remote Sens. 2019, 11(11) and references therein). Auxiliary data, e.g., wind speed, air-water interface reflectance, used for the data processing are added in the metadata. The PANTHYR provides reflectance measurements for a spectral range of 320–950 nm with a full-width half-maximum (FWHM) spectral resolution of 10 nm and a spectral sampling of 2.5 nm. The HYPSTAR Standard Range (SR) model provides visible and near-infrared (VNIR, 380-1020 nm) data with a spectral sampling (resolution) of ~0.5 nm (3 nm). The data are corrected for the NIR Similarity Spectrum (Ruddick et al., Limnol. Oceanogr., 2006, 51(2)) to remove any white error from inadequate skyglint correction. In addition, the following quality checks are performed and data are removed before distribution if: (1) the downwelling radiance/irradiance ratio is high (removing measurements affected by clouds in front of the sun or in the sky-viewing direction), (2) the coefficients of variation for the reflectance is high (removing high variability in illumination and/or target reflectance), (3) the retrieved reflectance is negative between 350 and 900 nm, and, (4) a reflectance bump is observed around 810 nm (removing bright waters). For the HYPSTAR data, uncertainties are also propagated through the full processing chain, including treatment of temporal and wavelength error-covariance, following the methodology defined in the Guide to the Expression of Uncertainty in Measurement (GUM). For more information about the data processing, see https://hypernets-processor.readthedocs.io/en/latest/content/atbd/atbd.html)" @default.
- 3e785f3e30239bbd2c572db9fe564e8b82707895 type ProvenanceStatement @default.