Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica
The surface reflection of solar radiation comprises an important boundary condition for solar radiative transfer simulations. In polar regions above snow surfaces, the surface reflection is particularly anisotropic due to low Sun elevations and the highly anisotropic scattering phase function of the...
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2020
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ftdoajarticles:oai:doaj.org/article:7004077e7fd9425f922070321ebb82ec 2023-05-15T13:36:12+02:00 Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica T. Carlsen G. Birnbaum A. Ehrlich V. Helm E. Jäkel M. Schäfer M. Wendisch 2020-11-01T00:00:00Z https://doi.org/10.5194/tc-14-3959-2020 https://doaj.org/article/7004077e7fd9425f922070321ebb82ec EN eng Copernicus Publications https://tc.copernicus.org/articles/14/3959/2020/tc-14-3959-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-3959-2020 1994-0416 1994-0424 https://doaj.org/article/7004077e7fd9425f922070321ebb82ec The Cryosphere, Vol 14, Pp 3959-3978 (2020) Environmental sciences GE1-350 Geology QE1-996.5 article 2020 ftdoajarticles https://doi.org/10.5194/tc-14-3959-2020 2022-12-31T01:23:01Z The surface reflection of solar radiation comprises an important boundary condition for solar radiative transfer simulations. In polar regions above snow surfaces, the surface reflection is particularly anisotropic due to low Sun elevations and the highly anisotropic scattering phase function of the snow crystals. The characterization of this surface reflection anisotropy is essential for satellite remote sensing over both the Arctic and Antarctica. To quantify the angular snow reflection properties, the hemispherical-directional reflectance factor (HDRF) of snow surfaces was derived from airborne measurements in Antarctica during austral summer in 2013/14. For this purpose, a digital 180 ∘ fish-eye camera (green channel, 490–585 nm wavelength band) was used. The HDRF was measured for different surface roughness conditions, optical-equivalent snow grain sizes, and solar zenith angles. The airborne observations covered an area of around 1000 km × 1000 km in the vicinity of Kohnen Station (75 ∘ 0 ′ S, 0 ∘ 4 ′ E) at the outer part of the East Antarctic Plateau. The observations include regions with higher (coastal areas) and lower (inner Antarctica) precipitation amounts and frequencies. The digital camera provided upward, angular-dependent radiance measurements from the lower hemisphere. The comparison of the measured HDRF derived for smooth and rough snow surfaces (sastrugi) showed significant differences, which are superimposed on the diurnal cycle. By inverting a semi-empirical kernel-driven bidirectional reflectance distribution function (BRDF) model, the measured HDRF of snow surfaces was parameterized as a function of solar zenith angle, surface roughness, and optical-equivalent snow grain size. This allows a direct comparison of the HDRF measurements with the BRDF derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite product MCD43. For the analyzed cases, MODIS observations (545–565 nm wavelength band) generally underestimated the anisotropy of the surface reflection. The largest ... Article in Journal/Newspaper Antarc* Antarctic Antarctica Arctic The Cryosphere Directory of Open Access Journals: DOAJ Articles Arctic Antarctic Austral Kohnen ENVELOPE(0.000,0.000,-75.000,-75.000) Kohnen Station ENVELOPE(0.000,0.000,-75.000,-75.000) Sastrugi ENVELOPE(163.683,163.683,-74.617,-74.617) The Cryosphere 14 11 3959 3978 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 T. Carlsen G. Birnbaum A. Ehrlich V. Helm E. Jäkel M. Schäfer M. Wendisch Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
The surface reflection of solar radiation comprises an important boundary condition for solar radiative transfer simulations. In polar regions above snow surfaces, the surface reflection is particularly anisotropic due to low Sun elevations and the highly anisotropic scattering phase function of the snow crystals. The characterization of this surface reflection anisotropy is essential for satellite remote sensing over both the Arctic and Antarctica. To quantify the angular snow reflection properties, the hemispherical-directional reflectance factor (HDRF) of snow surfaces was derived from airborne measurements in Antarctica during austral summer in 2013/14. For this purpose, a digital 180 ∘ fish-eye camera (green channel, 490–585 nm wavelength band) was used. The HDRF was measured for different surface roughness conditions, optical-equivalent snow grain sizes, and solar zenith angles. The airborne observations covered an area of around 1000 km × 1000 km in the vicinity of Kohnen Station (75 ∘ 0 ′ S, 0 ∘ 4 ′ E) at the outer part of the East Antarctic Plateau. The observations include regions with higher (coastal areas) and lower (inner Antarctica) precipitation amounts and frequencies. The digital camera provided upward, angular-dependent radiance measurements from the lower hemisphere. The comparison of the measured HDRF derived for smooth and rough snow surfaces (sastrugi) showed significant differences, which are superimposed on the diurnal cycle. By inverting a semi-empirical kernel-driven bidirectional reflectance distribution function (BRDF) model, the measured HDRF of snow surfaces was parameterized as a function of solar zenith angle, surface roughness, and optical-equivalent snow grain size. This allows a direct comparison of the HDRF measurements with the BRDF derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite product MCD43. For the analyzed cases, MODIS observations (545–565 nm wavelength band) generally underestimated the anisotropy of the surface reflection. The largest ... |
format |
Article in Journal/Newspaper |
author |
T. Carlsen G. Birnbaum A. Ehrlich V. Helm E. Jäkel M. Schäfer M. Wendisch |
author_facet |
T. Carlsen G. Birnbaum A. Ehrlich V. Helm E. Jäkel M. Schäfer M. Wendisch |
author_sort |
T. Carlsen |
title |
Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica |
title_short |
Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica |
title_full |
Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica |
title_fullStr |
Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica |
title_full_unstemmed |
Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica |
title_sort |
parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in antarctica |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-3959-2020 https://doaj.org/article/7004077e7fd9425f922070321ebb82ec |
long_lat |
ENVELOPE(0.000,0.000,-75.000,-75.000) ENVELOPE(0.000,0.000,-75.000,-75.000) ENVELOPE(163.683,163.683,-74.617,-74.617) |
geographic |
Arctic Antarctic Austral Kohnen Kohnen Station Sastrugi |
geographic_facet |
Arctic Antarctic Austral Kohnen Kohnen Station Sastrugi |
genre |
Antarc* Antarctic Antarctica Arctic The Cryosphere |
genre_facet |
Antarc* Antarctic Antarctica Arctic The Cryosphere |
op_source |
The Cryosphere, Vol 14, Pp 3959-3978 (2020) |
op_relation |
https://tc.copernicus.org/articles/14/3959/2020/tc-14-3959-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-3959-2020 1994-0416 1994-0424 https://doaj.org/article/7004077e7fd9425f922070321ebb82ec |
op_doi |
https://doi.org/10.5194/tc-14-3959-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
11 |
container_start_page |
3959 |
op_container_end_page |
3978 |
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1766075440149037056 |