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pOptical Earth observation satellites provide vast amounts of data on a daily basis. The top-of-atmosphere radiance measured by these satellites is usually converted to bottom-of-atmosphere radiance or reflectance which is then used for deriving numerous higher level products used for monitoring environmental conditions, climate change, stock of natural resources, etc. The increase of available remote sensing data impacts decision-making on both regional and global scales, and demands appropriate quality control and validation procedures. A HYperspectral Pointable System for Terrestrial and Aquatic Radiometry (HYPSTAR$^®$) has been designed to provide automated, italicin-situ/italic multiangular reflectance measurements of land and water targets. HYPSTAR-SR covers 380–1020 nm spectral range at 3 nm spectral resolution and is used at water sites. For land sites the HYPSTAR-XR variant is used with the spectral range extended to 1680 nm at 10 nm spectral resolution. The spectroradiometer has multiplexed radiance and irradiance entrances, an internal mechanical shutter, and an integrated imaging camera for capturing snapshots of the targets. The spectroradiometer is mounted on a two-axis pointing system with 360° range of free movement in both axes. The system also incorporates a stable light emitting diode as a light source, used for monitoring the stability of the radiometric calibration during the long-term unattended field deployment. Autonomous operation is managed by a host system which handles data acquisition, storage, and transmission to a central WATERHYPERNET or LANDHYPERNET server according to a pre-programmed schedule. The system is remotely accessible over the internet for configuration changes and software updates. The HYPSTAR systems have been deployed at 10 water and 11 land sites for different periods ranging from a few days to a few years. The data are automatically processed at the central servers by the HYPERNETS processor and the derived radiance, irradiance, and reflectance products with associated measurement uncertainties are distributed at the WATERHYPERNET and LANDHYPERNET data portals./p

pThis paper describes a prototype network of automated italicin situ/italic measurements of hyperspectral water reflectance suitable for satellite validation and water quality monitoring. Radiometric validation of satellite-derived water reflectance is essential to ensure that only reliable data, e.g., for estimating water quality parameters such as chlorophyll italica/italic concentration, reach end-users. Analysis of the differences between satellite and italicin situ/italic water reflectance measurements, particularly unmasked outliers, can provide recommendations on where satellite data processing algorithms need to be improved. In a massively multi-mission context, including Newspace constellations, hyperspectral missions and missions with broad spectral bands not designed for “water colour”, the advantage of hyperspectral over multispectral italicin situ/italic measurements is clear. Two hyperspectral measurement systems, PANTHYR (based on the mature TRIOS/RAMSES radiometer) and HYPSTAR$^®$ (a newly designed radiometer), have been integrated here in the WATERHYPERNET network with SI-traceable calibration and characterisation. The systems have common data acquisition protocol, data processing and quality control. The choice of validation site and viewing geometry and installation considerations are described in detail. Three demonstration cases are described: 1. PANTHYR data from two sites are used to validate Sentinel-2/MSI (A&B); 2. HYPSTAR$^®$ data at six sites are used to validate Sentinel-3/OLCI (A&B); 3. PANTHYR and HYPSTAR$^®$ data in Belgian North Sea waters are used to monitor phytoplankton parameters, including italicPhaeocystis globosa/italic, over two 5 month periods. Conclusion are drawn regarding the quality of Sentinel-2/MSI and Sentinel-3/OLCI data, including indications where improvements could be made. For example, a positive bias (mean difference) is found for ACOLITE\_DSF processing of Sentinel-2 in clear waters (Acqua Alta) and clues are provided on how to improve this processing. The utility of these italicin situ/italic measurements, even without accompanying hyperspectral satellite data, is demonstrated for phytoplankton monitoring. The future evolution of the WATERHYPERNET network is outlined, including geographical expansion, improvements to hardware reliability and to the measurement method (including uncertainty estimation) and plans for daily distribution of near real-time data./p

Nearly every geological subdiscipline relies to some degree on regional geological knowledge. In the introductory section of most geological papers it is standard practice to provide regional geological background information. Stratigraphic terminology is often well defined while other disciplinary concepts rely, at least to some degree, on generally agreed definitions or hierarchical schemes, such as paleontological, structural or magmatic terminology. This, however, is much less the case for the regional geological building blocks. Their names are usually composed of a combination of a geographical locality and a geological term. A few examples from Belgium are Brabant Massif, Campine Basin, Stavelot-Venn Inlier, and Malmedy Graben. Most of these have in common that, although their importance is well recognised, their definitions are vague and sometimes even conflicting, in that their meaning may differ between contexts and authors. Even if their meaning has drifted or become less exact, as a result of their frequent historical use, they commonly remain in use today. This issue is not exclusive to Belgium, but seems to be an altogether historic and worldwide phenomenon. Recently within Europe there is a growing awareness of this issue, resulting in important but rather isolated efforts to better structure and define regional information (Hintersberger et al. 2017; Németh 2021; Le Bayon et al. 2022) which have been brought together through pan-European cooperation (GSEU – Horizon Europe 101075609). The central element that seems to encompass most geologic features, is the lithotectonic unit (a distinct unit based on its partly separate geological history; URI: http://inspire.ec.europa.eu/codelist/GeologicUnitTypeValue/lithotectonicUnit). Grabens, basins and inliers are examples of lithotectonic units. In order to define and describe these units more accurately, lithotectonic limits are introduced. These are planar features, such as faults and unconformities, that correspond to the geologic events that formed the lithotectonic unit (Piessens et al. 2024). All information is organised and linked in vocabularies (thesauri) that together not only adequately define each concept, but also determine the relations between them, placing them in space and geological time (Plašienka 1999). This outlines the core methodology, around which 2D and 3D multi-scale visualisations are built, annotations can be added, existing ontologies can be linked (such as the ICS Geological Time Scale Ontology; Cox and Richard, 2005) and newly developed extensions such as the Modified Wilson Cycle (Németh 2021). As such, the work at Belgian level is closely linked to the ongoing international developments. Making use of the ongoing developments at European level, Belgium was the first country to set up a lithotectonic working group that became operational in 2023. Its first goal is to provide a lithotectonic framework that describes a starting set of main geological units and limits in Belgium, according to emerging European standards (the work at European level is linked to the implementation of INSPIRE and 195 is in communication with the GeoSciML community), by the end of 2024. The working group meets approximately every 2 months, and organisationally resides under the National Commission for Stratigraphy in Belgium. The working group will soon be looking for additional experts (junior and senior) in its continuing effort to identify and define broad superstructures, detail the regional geology to the more local level, to tackle new types of lithotectonic elements, or better address parts of geological history. Potential candidates are encouraged to contact one of the authors or the NCS secretariat. Cox SJD, Richard SM (2005) A formal model for the geologic time scale and global stratotype section and point, compatible with geospatial information transfer standards. Geosphere 1:119. https://doi.org/10.1130/GES00022.1 Hintersberger E, Iglseder C, Schuster R, Huet B (2017) The new database “Tectonic Boundaries” at the Geological Survey of Austria. Jahrbuch der geologischen Bundesanstalt 157:195–207 Le Bayon B, Padel M, Baudin T, et al (2022) The geological-event reference system, a step towards geological data harmonization. BSGF - Earth Sci Bull 193:18. https://doi.org/10.1051/bsgf/2022017 Németh Z (2021) Lithotectonic units of the Western Carpathians: Suggestion of simple methodology for lithotectonic units defining, applicable for orogenic belts world-wide. Mineralia Slovaca 2:81–90 Piessens K, Walstra J, Willems A, Barros R (2024) Old concepts in a new semantic perspective: introducing a geotemporal approach to conceptual definitions in geology. Life Sciences Plašienka D (1999) Definition and correlation of tectonic units with a special reference to some Central Western Carpathian examples. Mineralia Slovaca 31:3–16