Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone
The directional reflection of solar radiation by the Arctic Ocean is mainly shaped by two dominating surface types: sea ice (often snow-covered) and open ocean (ice-free). In the transitional zone between them, the marginal sea ice zone (MIZ), the surface reflection properties are determined by a mi...
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ftcopernicus:oai:publications.copernicus.org:amt99288 2023-05-15T15:00:54+02:00 Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone Becker, Sebastian Ehrlich, André Jäkel, Evelyn Carlsen, Tim Schäfer, Michael Wendisch, Manfred 2022-05-11 application/pdf https://doi.org/10.5194/amt-15-2939-2022 https://amt.copernicus.org/articles/15/2939/2022/ eng eng doi:10.5194/amt-15-2939-2022 https://amt.copernicus.org/articles/15/2939/2022/ eISSN: 1867-8548 Text 2022 ftcopernicus https://doi.org/10.5194/amt-15-2939-2022 2022-05-16T16:22:33Z The directional reflection of solar radiation by the Arctic Ocean is mainly shaped by two dominating surface types: sea ice (often snow-covered) and open ocean (ice-free). In the transitional zone between them, the marginal sea ice zone (MIZ), the surface reflection properties are determined by a mixture of the reflectance of both surface types. Retrieval methods applied over the MIZ need to take into account the mixed directional reflectivity; otherwise uncertainties in the retrieved atmospheric parameters over the MIZ may occur. To quantify these uncertainties, respective measurements of reflection properties of the MIZ are needed. Therefore, in this case study, an averaged hemispherical–directional reflectance factor (HDRF) of the inhomogeneous surface (mixture of sea ice and open ocean) in the MIZ is derived using airborne measurements collected with a digital fish-eye camera during a 20 min low-level flight leg in cloud-free conditions. For this purpose, a sea ice mask was developed to separate the reflectivity measurements from sea ice and open ocean and to derive separate HDRFs of the individual surface types. The respective results were compared with simulations and independent measurements available from the literature. It is shown that the open-ocean HDRF in the MIZ differs from homogeneous ocean surfaces due to wave attenuation. Using individual HDRFs of both surface types and the sea ice fraction, the mixed HDRF describing the directional reflectivity of the inhomogeneous surface of the MIZ was retrieved by a linear weighting procedure. Accounting for the wave attenuation, good agreement between the average measured HDRF and the constructed HDRF of the MIZ was found for the presented case study. Text Arctic Arctic Ocean Sea ice Copernicus Publications: E-Journals Arctic Arctic Ocean Atmospheric Measurement Techniques 15 9 2939 2953 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The directional reflection of solar radiation by the Arctic Ocean is mainly shaped by two dominating surface types: sea ice (often snow-covered) and open ocean (ice-free). In the transitional zone between them, the marginal sea ice zone (MIZ), the surface reflection properties are determined by a mixture of the reflectance of both surface types. Retrieval methods applied over the MIZ need to take into account the mixed directional reflectivity; otherwise uncertainties in the retrieved atmospheric parameters over the MIZ may occur. To quantify these uncertainties, respective measurements of reflection properties of the MIZ are needed. Therefore, in this case study, an averaged hemispherical–directional reflectance factor (HDRF) of the inhomogeneous surface (mixture of sea ice and open ocean) in the MIZ is derived using airborne measurements collected with a digital fish-eye camera during a 20 min low-level flight leg in cloud-free conditions. For this purpose, a sea ice mask was developed to separate the reflectivity measurements from sea ice and open ocean and to derive separate HDRFs of the individual surface types. The respective results were compared with simulations and independent measurements available from the literature. It is shown that the open-ocean HDRF in the MIZ differs from homogeneous ocean surfaces due to wave attenuation. Using individual HDRFs of both surface types and the sea ice fraction, the mixed HDRF describing the directional reflectivity of the inhomogeneous surface of the MIZ was retrieved by a linear weighting procedure. Accounting for the wave attenuation, good agreement between the average measured HDRF and the constructed HDRF of the MIZ was found for the presented case study. |
format |
Text |
author |
Becker, Sebastian Ehrlich, André Jäkel, Evelyn Carlsen, Tim Schäfer, Michael Wendisch, Manfred |
spellingShingle |
Becker, Sebastian Ehrlich, André Jäkel, Evelyn Carlsen, Tim Schäfer, Michael Wendisch, Manfred Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone |
author_facet |
Becker, Sebastian Ehrlich, André Jäkel, Evelyn Carlsen, Tim Schäfer, Michael Wendisch, Manfred |
author_sort |
Becker, Sebastian |
title |
Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone |
title_short |
Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone |
title_full |
Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone |
title_fullStr |
Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone |
title_full_unstemmed |
Airborne measurements of directional reflectivity over the Arctic marginal sea ice zone |
title_sort |
airborne measurements of directional reflectivity over the arctic marginal sea ice zone |
publishDate |
2022 |
url |
https://doi.org/10.5194/amt-15-2939-2022 https://amt.copernicus.org/articles/15/2939/2022/ |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Sea ice |
genre_facet |
Arctic Arctic Ocean Sea ice |
op_source |
eISSN: 1867-8548 |
op_relation |
doi:10.5194/amt-15-2939-2022 https://amt.copernicus.org/articles/15/2939/2022/ |
op_doi |
https://doi.org/10.5194/amt-15-2939-2022 |
container_title |
Atmospheric Measurement Techniques |
container_volume |
15 |
container_issue |
9 |
container_start_page |
2939 |
op_container_end_page |
2953 |
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1766332955483963392 |