Evaluating the EnMAP L2A normalized water leaving reflectance product over two years of mission

Abstract

The Environmental Mapping and Analysis Program (EnMAP), launched in April 2022 provides valuable data with 30 x 30 m spatial resolution and 244 spectral bands and this data is expected to improve our knowledge of inland and coastal waters. However, the atmospheric correction of satellite data obtained over water poses a significant challenge in aquatic remote sensing. Notably, the water leaving radiance in the visible spectrum constitutes usually not more than 10% of the total radiance at top of atmosphere. The remaining 90% of the signal primarily comprises atmospheric radiance and surface reflection, necessitating robust removal to mitigate significant uncertainties in the water products. To address this, we assess the quality and compare the EnMAP water reflectance products generated by three atmospheric correction processors: (i) Modular Inversion Program (MIP) used by the EnMAP ground segment (GS), (ii) Polymer and (iii) Acolite. This evaluation aims to understand and address these challenges for enhanced accuracy in EnMAP water reflectance products.