Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus
Two-dimensional horizontal fields of cloud optical thickness τ derived from airborne measurements of solar spectral, cloud-reflected radiance are compared with semi-idealized large eddy simulations (LESs) of Arctic stratus performed with the Consortium for Small-scale Modeling (COSMO) atmospheric mo...
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ftcopernicus:oai:publications.copernicus.org:acp66303 2023-05-15T14:51:06+02:00 Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus Schäfer, Michael Loewe, Katharina Ehrlich, André Hoose, Corinna Wendisch, Manfred 2019-02-01 application/pdf https://doi.org/10.5194/acp-18-13115-2018 https://www.atmos-chem-phys.net/18/13115/2018/ eng eng doi:10.5194/acp-18-13115-2018 https://www.atmos-chem-phys.net/18/13115/2018/ eISSN: 1680-7324 Text 2019 ftcopernicus https://doi.org/10.5194/acp-18-13115-2018 2019-12-24T09:49:56Z Two-dimensional horizontal fields of cloud optical thickness τ derived from airborne measurements of solar spectral, cloud-reflected radiance are compared with semi-idealized large eddy simulations (LESs) of Arctic stratus performed with the Consortium for Small-scale Modeling (COSMO) atmospheric model. The measurements were collected during the Vertical Distribution of Ice in Arctic Clouds (VERDI) campaign carried out in Inuvik, Canada, in April/May 2012. The input for the LESs is obtained from collocated airborne dropsonde observations of a persistent Arctic stratus above the sea-ice-free Beaufort Sea. Simulations are performed for spatial resolutions of 50 m (1.6 km × 1.6 km domain) and 100 m (6.4 km × 6.4 km domain). Macrophysical cloud properties, such as cloud top altitude and vertical extent, are well captured by the COSMO simulations. However, COSMO produces rather homogeneous clouds compared to the measurements, in particular for the simulations with coarser spatial resolution. For both spatial resolutions, the directional structure of the cloud inhomogeneity is well represented by the model. Differences between the individual cases are mainly associated with the wind shear near cloud top and the vertical structure of the atmospheric boundary layer. A sensitivity study changing the wind velocity in COSMO by a vertically constant scaling factor shows that the directional, small-scale cloud inhomogeneity structures can range from 250 to 800 m, depending on the mean wind speed, if the simulated domain is large enough to capture also large-scale structures, which then influence the small-scale structures. For those cases, a threshold wind velocity is identified, which determines when the cloud inhomogeneity stops increasing with increasing wind velocity. Text Arctic Beaufort Sea Inuvik Sea ice Copernicus Publications: E-Journals Arctic Canada Inuvik ENVELOPE(-133.610,-133.610,68.341,68.341) Atmospheric Chemistry and Physics 18 17 13115 13133 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Two-dimensional horizontal fields of cloud optical thickness τ derived from airborne measurements of solar spectral, cloud-reflected radiance are compared with semi-idealized large eddy simulations (LESs) of Arctic stratus performed with the Consortium for Small-scale Modeling (COSMO) atmospheric model. The measurements were collected during the Vertical Distribution of Ice in Arctic Clouds (VERDI) campaign carried out in Inuvik, Canada, in April/May 2012. The input for the LESs is obtained from collocated airborne dropsonde observations of a persistent Arctic stratus above the sea-ice-free Beaufort Sea. Simulations are performed for spatial resolutions of 50 m (1.6 km × 1.6 km domain) and 100 m (6.4 km × 6.4 km domain). Macrophysical cloud properties, such as cloud top altitude and vertical extent, are well captured by the COSMO simulations. However, COSMO produces rather homogeneous clouds compared to the measurements, in particular for the simulations with coarser spatial resolution. For both spatial resolutions, the directional structure of the cloud inhomogeneity is well represented by the model. Differences between the individual cases are mainly associated with the wind shear near cloud top and the vertical structure of the atmospheric boundary layer. A sensitivity study changing the wind velocity in COSMO by a vertically constant scaling factor shows that the directional, small-scale cloud inhomogeneity structures can range from 250 to 800 m, depending on the mean wind speed, if the simulated domain is large enough to capture also large-scale structures, which then influence the small-scale structures. For those cases, a threshold wind velocity is identified, which determines when the cloud inhomogeneity stops increasing with increasing wind velocity. |
format |
Text |
author |
Schäfer, Michael Loewe, Katharina Ehrlich, André Hoose, Corinna Wendisch, Manfred |
spellingShingle |
Schäfer, Michael Loewe, Katharina Ehrlich, André Hoose, Corinna Wendisch, Manfred Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus |
author_facet |
Schäfer, Michael Loewe, Katharina Ehrlich, André Hoose, Corinna Wendisch, Manfred |
author_sort |
Schäfer, Michael |
title |
Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus |
title_short |
Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus |
title_full |
Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus |
title_fullStr |
Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus |
title_full_unstemmed |
Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus |
title_sort |
simulated and observed horizontal inhomogeneities of optical thickness of arctic stratus |
publishDate |
2019 |
url |
https://doi.org/10.5194/acp-18-13115-2018 https://www.atmos-chem-phys.net/18/13115/2018/ |
long_lat |
ENVELOPE(-133.610,-133.610,68.341,68.341) |
geographic |
Arctic Canada Inuvik |
geographic_facet |
Arctic Canada Inuvik |
genre |
Arctic Beaufort Sea Inuvik Sea ice |
genre_facet |
Arctic Beaufort Sea Inuvik Sea ice |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-18-13115-2018 https://www.atmos-chem-phys.net/18/13115/2018/ |
op_doi |
https://doi.org/10.5194/acp-18-13115-2018 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
18 |
container_issue |
17 |
container_start_page |
13115 |
op_container_end_page |
13133 |
_version_ |
1766322168524701696 |