Retrieval of water constituents from hyperspectral in-situ measurements under variable cloud cover
- Remote sensing and field spectroscopy of natural waters is typically performed under clear skies, low wind speeds and low solar zenith angles. Such measurements can also be made, in principle, under clouds and mixed skies using airborne or in-situ measurements; however, variable illumination conditions pose a challenge to data analysis. In the present case study, we evaluated the inversion of hyperspectral in-situ measurements for water constituent retrieval acquired under variable cloud cover. First, we studied the retrieval of Chlorophyll-a (Chl-a) concentration and colored dissolved organic matter (CDOM) absorption from in-water irradiance measurements. Then, we evaluated the errors in the retrievals of the concentration of total suspended matter (TSM), Chl-a and the absorption coefficient of CDOM from above-water reflectance measurements due to highly variable reflections at the water surface. In order to approximate cloud reflections, we extended a recent three-component surface reflectance model for cloudless atmospheres by aRemote sensing and field spectroscopy of natural waters is typically performed under clear skies, low wind speeds and low solar zenith angles. Such measurements can also be made, in principle, under clouds and mixed skies using airborne or in-situ measurements; however, variable illumination conditions pose a challenge to data analysis. In the present case study, we evaluated the inversion of hyperspectral in-situ measurements for water constituent retrieval acquired under variable cloud cover. First, we studied the retrieval of Chlorophyll-a (Chl-a) concentration and colored dissolved organic matter (CDOM) absorption from in-water irradiance measurements. Then, we evaluated the errors in the retrievals of the concentration of total suspended matter (TSM), Chl-a and the absorption coefficient of CDOM from above-water reflectance measurements due to highly variable reflections at the water surface. In order to approximate cloud reflections, we extended a recent three-component surface reflectance model for cloudless atmospheres by a constant offset and compared different surface reflectance correction procedures. Our findings suggest that in-water irradiance measurements may be used for the analysis of absorbing compounds even under highly variable weather conditions. The extended surface reflectance model proved to contribute to the analysis of above-water reflectance measurements with respect to Chl-a and TSM. Results indicate the potential of this approach for all-weather monitoring.…
Author details: | Anna Göritz, Stella A. BergerORCiD, Peter GegeORCiD, Hans-Peter GrossartORCiDGND, Jens C. Nejstgaard, Sebastian RiedelORCiD, Rüdiger Röttgers, Christian Utschig |
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DOI: | https://doi.org/10.3390/rs10020181 |
ISSN: | 2072-4292 |
Title of parent work (English): | Remote sensing / Molecular Diversity Preservation International (MDPI) |
Subtitle (English): | a case study at Lake Stechlin (Germany) |
Publisher: | MDPI |
Place of publishing: | Basel |
Publication type: | Article |
Language: | English |
Date of first publication: | 2018/01/26 |
Publication year: | 2018 |
Release date: | 2022/02/02 |
Tag: | bio-optical modeling; cloud; hyperspectral measurements; in-situ; inland water; inversion; remote sensing; surface reflection |
Volume: | 10 |
Issue: | 2 |
Number of pages: | 19 |
Funding institution: | Brockmann Consult GmbH; EOMAP GmbH Co. KG; Helmholtz-Zentrum fur Umwelt (UFZ); Deutsches Zentrum fur Luft- und Raumfahrt (DLR)Helmholtz AssociationGerman Aerospace Centre (DLR); Leibniz-Institut fur Gewasserforschung- und Binnenfischerei (IGB); Kiel University (CAU); Technical University of Munich (TUM); Deutsche Forschungsgemeinschaft (DFG) through the TUM International Graduate School of Science and Engineering (IGSSE)German Research Foundation (DFG); TUM Laura-Bassi-Fellowship; Federal Ministry for Economic Affairs and Energy, Germany [50EE1020]; DFGGerman Research Foundation (DFG) [GR1540/21-1, GR1540/29-1] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie |
Peer review: | Referiert |
Publishing method: | Open Access / Gold Open-Access |
DOAJ gelistet | |
License (German): | CC-BY - Namensnennung 4.0 International |