Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation
Comprehensive aircraft observations are used to characterise surface roughness over the Arctic marginal ice zone (MIZ) and consequently make recommendations for the parametrisation of surface momentum exchange in the MIZ. These observations were gathered in the Barents Sea and Fram Strait from two a...
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ftcopernicus:oai:publications.copernicus.org:acp31933 2023-05-15T13:11:40+02:00 Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation Elvidge, A. D. Renfrew, I. A. Weiss, A. I. Brooks, I. M. Lachlan-Cope, T. A. King, J. C. 2018-09-09 application/pdf https://doi.org/10.5194/acp-16-1545-2016 https://www.atmos-chem-phys.net/16/1545/2016/ eng eng doi:10.5194/acp-16-1545-2016 https://www.atmos-chem-phys.net/16/1545/2016/ eISSN: 1680-7324 Text 2018 ftcopernicus https://doi.org/10.5194/acp-16-1545-2016 2019-12-24T09:52:47Z Comprehensive aircraft observations are used to characterise surface roughness over the Arctic marginal ice zone (MIZ) and consequently make recommendations for the parametrisation of surface momentum exchange in the MIZ. These observations were gathered in the Barents Sea and Fram Strait from two aircraft as part of the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project. They represent a doubling of the total number of such aircraft observations currently available over the Arctic MIZ. The eddy covariance method is used to derive estimates of the 10 m neutral drag coefficient ( C DN10 ) from turbulent wind velocity measurements, and a novel method using albedo and surface temperature is employed to derive ice fraction. Peak surface roughness is found at ice fractions in the range 0.6 to 0.8 (with a mean interquartile range in C DN10 of 1.25 to 2.85 × 10 −3 ). C DN10 as a function of ice fraction is found to be well approximated by the negatively skewed distribution provided by a leading parametrisation scheme (Lüpkes et al., 2012) tailored for sea-ice drag over the MIZ in which the two constituent components of drag – skin and form drag – are separately quantified. Current parametrisation schemes used in the weather and climate models are compared with our results and the majority are found to be physically unjustified and unrepresentative. The Lüpkes et al. (2012) scheme is recommended in a computationally simple form, with adjusted parameter settings. A good agreement holds for subsets of the data from different locations, despite differences in sea-ice conditions. Ice conditions in the Barents Sea, characterised by small, unconsolidated ice floes, are found to be associated with higher C DN10 values – especially at the higher ice fractions – than those of Fram Strait, where typically larger, smoother floes are observed. Consequently, the important influence of sea-ice morphology and floe size on surface roughness is recognised, and improvement in the representation of this in parametrisation schemes is suggested for future study. Text albedo Arctic Barents Sea Fram Strait Sea ice Copernicus Publications: E-Journals Arctic Barents Sea Atmospheric Chemistry and Physics 16 3 1545 1563 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Comprehensive aircraft observations are used to characterise surface roughness over the Arctic marginal ice zone (MIZ) and consequently make recommendations for the parametrisation of surface momentum exchange in the MIZ. These observations were gathered in the Barents Sea and Fram Strait from two aircraft as part of the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project. They represent a doubling of the total number of such aircraft observations currently available over the Arctic MIZ. The eddy covariance method is used to derive estimates of the 10 m neutral drag coefficient ( C DN10 ) from turbulent wind velocity measurements, and a novel method using albedo and surface temperature is employed to derive ice fraction. Peak surface roughness is found at ice fractions in the range 0.6 to 0.8 (with a mean interquartile range in C DN10 of 1.25 to 2.85 × 10 −3 ). C DN10 as a function of ice fraction is found to be well approximated by the negatively skewed distribution provided by a leading parametrisation scheme (Lüpkes et al., 2012) tailored for sea-ice drag over the MIZ in which the two constituent components of drag – skin and form drag – are separately quantified. Current parametrisation schemes used in the weather and climate models are compared with our results and the majority are found to be physically unjustified and unrepresentative. The Lüpkes et al. (2012) scheme is recommended in a computationally simple form, with adjusted parameter settings. A good agreement holds for subsets of the data from different locations, despite differences in sea-ice conditions. Ice conditions in the Barents Sea, characterised by small, unconsolidated ice floes, are found to be associated with higher C DN10 values – especially at the higher ice fractions – than those of Fram Strait, where typically larger, smoother floes are observed. Consequently, the important influence of sea-ice morphology and floe size on surface roughness is recognised, and improvement in the representation of this in parametrisation schemes is suggested for future study. |
format |
Text |
author |
Elvidge, A. D. Renfrew, I. A. Weiss, A. I. Brooks, I. M. Lachlan-Cope, T. A. King, J. C. |
spellingShingle |
Elvidge, A. D. Renfrew, I. A. Weiss, A. I. Brooks, I. M. Lachlan-Cope, T. A. King, J. C. Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation |
author_facet |
Elvidge, A. D. Renfrew, I. A. Weiss, A. I. Brooks, I. M. Lachlan-Cope, T. A. King, J. C. |
author_sort |
Elvidge, A. D. |
title |
Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation |
title_short |
Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation |
title_full |
Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation |
title_fullStr |
Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation |
title_full_unstemmed |
Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation |
title_sort |
observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation |
publishDate |
2018 |
url |
https://doi.org/10.5194/acp-16-1545-2016 https://www.atmos-chem-phys.net/16/1545/2016/ |
geographic |
Arctic Barents Sea |
geographic_facet |
Arctic Barents Sea |
genre |
albedo Arctic Barents Sea Fram Strait Sea ice |
genre_facet |
albedo Arctic Barents Sea Fram Strait Sea ice |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-16-1545-2016 https://www.atmos-chem-phys.net/16/1545/2016/ |
op_doi |
https://doi.org/10.5194/acp-16-1545-2016 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
16 |
container_issue |
3 |
container_start_page |
1545 |
op_container_end_page |
1563 |
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1766248456944353280 |