TY  - GEN
A1  - Göritz, Anna
A1  - Berger, Stella A.
A1  - Gege, Peter
A1  - Grossart, Hans-Peter
A1  - Nejstgaard, Jens C.
A1  - Riedel, Sebastian
A1  - Röttgers, Rüdiger
A1  - Utschig, Christian
T1  - Retrieval of water constituents from hyperspectral in-situ measurements under variable cloud cover
BT  - a case study at lake Stechlin (Germany)
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - 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 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.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 941 
KW  - remote sensing
KW  - inland water
KW  - hyperspectral measurements
KW  - in-situ
KW  - cloud
KW  - surface reflection
KW  - inversion
KW  - bio-optical modeling
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-459837
SN  - 1866-8372
IS  - 941
ER  - 
TY  - JOUR
A1  - Göritz, Anna
A1  - Berger, Stella A.
A1  - Gege, Peter
A1  - Grossart, Hans-Peter
A1  - Nejstgaard, Jens C.
A1  - Riedel, Sebastian
A1  - Röttgers, Rüdiger
A1  - Utschig, Christian
T1  - Retrieval of water constituents from hyperspectral in-situ measurements under variable cloud cover
BT  - a case study at Lake Stechlin (Germany)
JF  - Remote sensing / Molecular Diversity Preservation International (MDPI)
N2  - 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 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.
KW  - remote sensing
KW  - inland water
KW  - hyperspectral measurements
KW  - in-situ
KW  - cloud
KW  - surface reflection
KW  - inversion
KW  - bio-optical modeling
Y1  - 2018
U6  - https://doi.org/10.3390/rs10020181
SN  - 2072-4292
VL  - 10
IS  - 2
PB  - MDPI
CY  - Basel
ER  -