Earth’s artificially lit area is expanding at 2.2% per year, with existing lit areas brightening by 2.2% per year.

Imaging spectroscopy, also known as hyperspectral remote sensing, is based on the characterization of Earth surface materials and processes through spectrally-resolved measurements of the light interacting with matter. The potential of imaging spectroscopy for Earth remote sensing has been demonstrated since the 1980s. However, most of the developments and applications in imaging spectroscopy have largely relied on airborne spectrometers, as the amount and quality of space-based imaging spectroscopy data remain relatively low to date. The upcoming Environmental Mapping and Analysis Program (EnMAP) German imaging spectroscopy mission is intended to fill this gap. An overview of the main characteristics and current status of the mission is provided in this contribution. The core payload of EnMAP consists of a dual-spectrometer instrument measuring in the optical spectral range between 420 and 2450 nm with a spectral sampling distance varying between 5 and 12 nm and a reference signal-to-noise ratio of 400:1 in the visible and near-infrared and 180:1 in the shortwave-infrared parts of the spectrum. EnMAP images will cover a 30 km-wide area in the across-track direction with a ground sampling distance of 30 m. An across-track tilted observation capability will enable a target revisit time of up to four days at the Equator and better at high latitudes. EnMAP will contribute to the development and exploitation of spaceborne imaging spectroscopy applications by making high-quality data freely available to scientific users worldwide.

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The influence of plant and canopy architecture on canopy bidirectional reflectance and the BRDF is subject of this study. To understand BRDF-influenced reflectance signals, this influence must be identified and quantified, which requires detailed knowledge concerning the structure and BRDF of the observed canopies. BRDF measurements of in-situ canopies are time-consuming and depend on the availability of a field goniometer. In contrast to field measurements, computer based simulations of the canopy BRDF offer an alternative approach that considers parameter-driven setups of virtual canopies under constant illumination conditions. This paper presents the HySimCaR system, which has been developed in the context of the EnMAP mission. This spectral, spatial and temporal simulation system consists of detailed virtual 3D cereal canopies of different phenological stages, whose geometries are linked to corresponding spectral information. The system enables the simulation of realistic bidirectional reflectance spectra on the basis of virtual 3D scenarios by incorporating any possible viewing position with ray tracing techniques. The parameterization of a number of canopy structure parameters, such as phenological stage, row distance and row orientation, enables the modeling of the bidirectional reflectance and based on them the approximation of the BRDF for many structurally different cereal canopies. HySimCaR has been validated with respect to structural and spectral accuracy using three cereal types, including wheat, rye and barley, and 13 different phenological stages. The results show that the virtual cereal canopies are recreated in a realistic way, and it is possible to model their detailed canopy bidirectional reflectance and their BRDF using HySimCaR.