Status of the Imaging Spectroscopy Mission Enmap With Radiometric Calibration and Correction

Abstract

Abstract. The high-resolution imaging spectroscopy remote sensing mission EnMAP (Environmental Mapping and Analysis Program, enmap.org) covers the spectral range from 420 nm to 2450 nm with a spectral sampling distance varying between 4.8 nm and 12.0 nm comprising 262 spectral bands. We focus on the planned framework concerning radiometry. The expected signal-to-noise ratio at reference radiance level is 500:1 at 495 nm and 150:1 at 2200 nm. The radiometric resolution is 14 bits and an absolute radiometric accuracy of better than 5% is achieved. Radiometric calibration is based on Sun calibration measurements with a fullaperture diffusor for absolute calibration. In addition, relative calibration monitors the instrument during the complete mission lifetime based on an integrating sphere (on the satellite). The fully-automatic on-ground image processing chain considers the derived radiometric calibration coefficients in the radiometric correction which is followed by the orthorectification and atmospheric compensation. Each of the two 2-dimensional detector arrays of the prism-based pushbroom dual-spectrometer works in a dual-gain configuration to cover the complete dynamic range. EnMAP will acquire 30 km in the across-track direction with a ground sampling distance of 30 m and the across-track tilt capability of 30° will enable a target revisit time of less than 4 days. The launch is scheduled for 2021. The high-quality products will be freely available to international scientific users for measuring and analysing diagnostic parameters which describe vital processes on the Earth’s surface.

Use of Hyper-Spectral Visible and Near-Infrared Satellite Data for Timely Estimates of the Earth’s Surface Reflectance in Cloudy and Aerosol Loaded Conditions: Part 1–Application to RGB Image Restoration Over Land With GOME-2

“…For example, the European Space Agency (ESA) FLuORescence Imaging Spectrometer (FLORIS) on the FLuorescence EXplorer (FLEX) mission will fly in low Earth orbit with approximately 300 m spatial resolution and spectral coverage from 500 to 780 nm (i.e., green through NIR) over a 250 km swath (Coppo et al, 2017). The NASA surface biology and geology (SBG) and the German Environmental Mapping and Analysis Program (EnMAP) (Storch et al, 2020) will produce hyper-spectral imagery using wavelengths from the visible through SWIR. These instruments are particularly well suited for applications related to land biochemical processes.…”

Use of Hyper-Spectral Visible and Near-Infrared Satellite Data for Timely Estimates of the Earth’s Surface Reflectance in Cloudy Conditions: Part 2- Image Restoration With HICO Satellite Data in Overcast Conditions

“…These include the German Aerospace Center (DLR) Earth Sensing Imaging Spectrometer (DESIS) (Krutz et al, 2019), the Japanese Ministry of Economy, Trade, and Industry (METI) Hyperspectral Imager Suite (HISUI), and the NASA Earth Surface Mineral Dust Source Investigation (EMIT), all currently flying on the ISS, as well as with similar spectral coverage and GSD of ∼30 m (Krutz et al, 2019), the Italian Space Agency's (ASI) Hyperspectral Precursor of the Application Mission (PRISMA). The next few years will see the launches of the German Environmental Mapping and Analysis Program (EnMAP) (Storch et al, 2020), the European Space Agency (ESA) Copernicus Hyperspectral Imaging Mission (CHIME), and NASA surface biology and geology (SBG) mission. Hyper-spectral instruments can also be operated from the ground or flown on airborne platforms.…”

Analysis-Ready Data from Hyperspectral Sensors—The Design of the EnMAP CARD4L-SR Data Product

“…Additional measurements looking into deep space for monitoring shutter thermal emission and closed shutter measurements before and after each observation for subtraction of dark signal complement the calibration. Using these procedures, the target radiometric accuracy is better than 5% [23].…”