Hyperspectral remote sensing provides measurements over hundreds of bands from the visible to the infrared. This allows to explore the subtle optical spectral differences, especially in water. Building on this technology, a new generation of space-borne sensors for terrestrial and aquatic applications has been sent to space. In April 2022, Germany's hyperspectral satellite mission “EnMAP” was launched.
For its standard product, EnMAP applies a dedicated water atmospheric correction (AC) called the Modular Inversion Program (MIP), developed by EOMAP physicists.
Why atmospheric correction matters
Being able to accurately predict water reflectances is one of the most important benchmarks of aquatic remote sensing algorithms. Every error in reflectance prediction propagates, thus producing errors in quantities of interest. For users of EO derivatives, such as bathymetry (shown in the figure), water quality parameters, and ocean colour, atmospheric correction routines are key to ensuring standardized and high-quality outputs.
First assessment of water reflectance products
In the journal "Optics Express", 21 scientists from leading European research institutions have published the first extensive assessment of the water reflectance products from EnMAP. The geospatial experts evaluated EnMAP’s standard normalized water leaving reflectance over 17 sites – including Lake Constance, Chesapeake Bay and the Great Barrier Reef - in the first two years of the mission.
MIP technology by EOMAP superior
This intercomparison between three AC methods - MIP, Polymer and Acolite - has shown superior results for MIP (EOMAP’s solution): The data showed very good agreement between in situ hyperspectral match-ups and EnMAP. In addition, the superior performance of MIP was confirmed by the validation results obtained with the multispectral match-up dataset. “The best results were obtained for the MIP AC and demonstrated the robustness of the standard EnMAP [pW]N products”, the scientists conclude.
The study not only testifies EOMAP’s AC method, but also confirms the great potential of EnMAP hyperspectral data for a better understanding of inland and coastal waters.
Read the full paper by Mariana Soppa et al. in Optics Express.
Please reach out to info@eomap.de for further details.
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