The Hyperspectral Imager for the Coastal Ocean (HICO) is the first spaceborne hyperspectral sensor designed specifically for the coastal ocean and estuarial, riverine, or other shallow-water areas. The HICO generates hyperspectral images, primarily over the 400-900 nm spectral range, with a ground sample distance of ≈90 m (at nadir) and a high signal-to-noise ratio. The HICO is now operating on the International Space Station (ISS). Its cross-track and along-track fields of view are 42 km (at nadir) and 192 km, respectively, for a total scene area of 8000 km(2). The HICO is an innovative prototype sensor that builds on extensive experience with airborne sensors and makes extensive use of commercial off-the-shelf components to build a space sensor at a small fraction of the usual cost and time. Here we describe the instrument's design and characterization and present early images from the ISS.

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Abstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of hedgerows is useful in many fields of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a hedgerow on rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a hedgerow perpendicular to the slope was monitored. To evaluate hedgerow rainfall interception, rainfall was measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 m downslope perpendicularly away from the hedgerow. The strongest correlation between rainfall next to the hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the hedgerow on spatial rainfall distribution was related to distance from the hedgerow and rainfall amount. Annual distribution of soil-water potential showed that the hedgerow influenced it up to 9 m upslope and 6 m downslope, the area in which most of the hedgerow's roots were observed. The soil was driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the hedgerow in summer and autumn. These results indicate that at the local scale hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around hedgerows should be integrated into relevant hydrological models, especially for catchments with a dense hedgerow network.

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Experimental results of a study of the photoluminescence of microcrystalline Tl[Au(CN)2] as a function of temperature (1.7-400 K) and magnetic field (0-6 T) are described. These results, along with relativistically modified extended Hückel calculations, provide evidence that covalent Tl-Au interactions alter its spectroscopic properties in comparison with isostructural Cs[Au(CN)2], Specifically, the absorption and luminescence of Tl[Au(CN)2] appear at lower energies than for Cs[Au(CN)2], and a comparison of the luminescence spectra and lifetimes for the two compounds reveals evidence for an increased rate of intersystem crossing in T1[Au(CN)2] relative to Cs[Au(CN)2], Both effects are reflective of covalent Tl-Au interactions in Tl[Au(CN)2]. The electronic structure calculations clearly demonstrate the covalency of both the Tl-Au and Au-Au interactions in Tl[Au(CN)2] and reveal specific orbital contributions responsible for these interactions. Relativistic effects are shown to play an important role in the Tl-Au and Au-Au bonding.