The EnMAP Ground Segment Processor for aquatic applications

Abstract

EnMAP, the Environmental Mapping and Analysis Program, is a German satellite mission that was successfully launched in April 2022. EnMAP is an optical (VNIR/SWIR) remote sensing mission with high spatial (30 m GSD) and spectral (FWHM ~6-12 nm) resolution. While initially designed for terrestrial applications, EnMAP holds significant potential for aquatic studies due to its hyperspectral capabilities. EnMAP ground segment processing is pioneering by providing separate processing chains for land and water, allowing tailored data processing for each application. It also includes a sunglint avoidance mechanism using EnMAP’s tilting capability for mitigating the impact of sunglint-contaminated pixels in specific geographical constellations. The EnMAP satellite is equipped with a VNIR-SWIR push-broom hyperspectral imager that covers a spectral range from 420 to 2450 nm and comprises 224 contiguous spectral bands. EnMAP follows a sun-synchronous orbit with a revisit period of 27 days, extendable to less than four days through off-nadir pointing capabilities. Users have access to three product levels: L1B, L1C, and L2A. What stands out is its separate processing chains for land and water pixels within the L2A processing, offering two types of water reflectance data: subsurface irradiance reflectance and normalized water leaving reflectance. The paper explores the advantages of EnMAP's ground segment processing chain and its applications in aquatic research, highlighting the significance of accurate water reflectance data. The optimized processing enhances data quality, rendering terrestrial sensors more applicable for monitoring aquatic ecosystems. EnMAP thus provides a unique opportunity to understand aquatic ecosystems paving the way for future hyperspectral missions.