Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence
The two-dimensional (2D) spectral properties, including the degree of isotropy, of under-ice roughness in the Beaufort Gyre were investigated. Under-ice roughness plays an important role in turbulent ocean heat, salt, and momentum fluxes that determine the delicate balance between surface forcing an...
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ftdtic:ADA479954 2023-05-15T14:54:29+02:00 Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence McGeehan, Timothy P. NAVAL POSTGRADUATE SCHOOL MONTEREY CA 2008-03 text/html http://www.dtic.mil/docs/citations/ADA479954 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA479954 en eng http://www.dtic.mil/docs/citations/ADA479954 Approved for public release; distribution is unlimited. DTIC Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE FORMATION *ROUGHNESS *ARCTIC OCEAN *UNDERICE MATHEMATICAL MODELS SIMULATION LAYERS FLUX(RATE) MOTION SPECTRA ERROR ANALYSIS MIXING TEST SETS MOORING SEA ICE MOMENTUM FUNCTIONS(MATHEMATICS) LOW STRENGTH TRAJECTORIES HEAT ANISOTROPY ICE ESTIMATES AUTOCORRELATION THESES TURBULENCE MONTE CARLO METHOD PRESSURE RIDGES ICE KEELS ICE ROUGHNESS BEAUFORT GYRE Text 2008 ftdtic 2016-02-22T14:45:11Z The two-dimensional (2D) spectral properties, including the degree of isotropy, of under-ice roughness in the Beaufort Gyre were investigated. Under-ice roughness plays an important role in turbulent ocean heat, salt, and momentum fluxes that determine the delicate balance between surface forcing and the ocean interior that sustains or reduces the perennial ice cover. Accurate characterization of this roughness is important for numerical modeling and prediction of the Arctic air-ice-ocean system, which will play a significant role as the US Navy increases its strategic presence in the ice-diminished Arctic Ocean. Ice draft data from moored upward looking echosounders of the Beaufort Gyre Exploration Project and ice motion derived from trajectories of International Arctic Buoy Program buoys were combined to create directional sections of ice draft. Autocorrelation functions were created for each segment which were then combined to make a 2D autocorrelation function. The 2D FFT was taken of this in order to yield a 2D spectrum, from which isotropy and other spectral properties could be determined. The processing routine was tested on several synthetic test datasets and in each case produced the correct output. Two years of data from three moorings in the Beaufort all provided 2D spectra which showed weak anisotropy of the under-ice roughness. Error estimates were determined by Monte Carlo simulations. For each dataset, most of the variance of the underside morphology was contained in a wavenumber band between 0.001 and 0.01m-1 (100-1000m). There were no distinct, preferred wavelengths. Spectral levels ranged from 1.2 - 4.2 x 104 m2 for Mooring C (2004-2005) to 0.2 1.6 x 104 m2 for Mooring A (2004-2005). Text Arctic Arctic Ocean Ice International Arctic Buoy Program permafrost Sea ice Defense Technical Information Center: DTIC Technical Reports database Arctic Arctic Ocean |
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Open Polar |
collection |
Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE FORMATION *ROUGHNESS *ARCTIC OCEAN *UNDERICE MATHEMATICAL MODELS SIMULATION LAYERS FLUX(RATE) MOTION SPECTRA ERROR ANALYSIS MIXING TEST SETS MOORING SEA ICE MOMENTUM FUNCTIONS(MATHEMATICS) LOW STRENGTH TRAJECTORIES HEAT ANISOTROPY ICE ESTIMATES AUTOCORRELATION THESES TURBULENCE MONTE CARLO METHOD PRESSURE RIDGES ICE KEELS ICE ROUGHNESS BEAUFORT GYRE |
spellingShingle |
Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE FORMATION *ROUGHNESS *ARCTIC OCEAN *UNDERICE MATHEMATICAL MODELS SIMULATION LAYERS FLUX(RATE) MOTION SPECTRA ERROR ANALYSIS MIXING TEST SETS MOORING SEA ICE MOMENTUM FUNCTIONS(MATHEMATICS) LOW STRENGTH TRAJECTORIES HEAT ANISOTROPY ICE ESTIMATES AUTOCORRELATION THESES TURBULENCE MONTE CARLO METHOD PRESSURE RIDGES ICE KEELS ICE ROUGHNESS BEAUFORT GYRE McGeehan, Timothy P. Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence |
topic_facet |
Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE FORMATION *ROUGHNESS *ARCTIC OCEAN *UNDERICE MATHEMATICAL MODELS SIMULATION LAYERS FLUX(RATE) MOTION SPECTRA ERROR ANALYSIS MIXING TEST SETS MOORING SEA ICE MOMENTUM FUNCTIONS(MATHEMATICS) LOW STRENGTH TRAJECTORIES HEAT ANISOTROPY ICE ESTIMATES AUTOCORRELATION THESES TURBULENCE MONTE CARLO METHOD PRESSURE RIDGES ICE KEELS ICE ROUGHNESS BEAUFORT GYRE |
description |
The two-dimensional (2D) spectral properties, including the degree of isotropy, of under-ice roughness in the Beaufort Gyre were investigated. Under-ice roughness plays an important role in turbulent ocean heat, salt, and momentum fluxes that determine the delicate balance between surface forcing and the ocean interior that sustains or reduces the perennial ice cover. Accurate characterization of this roughness is important for numerical modeling and prediction of the Arctic air-ice-ocean system, which will play a significant role as the US Navy increases its strategic presence in the ice-diminished Arctic Ocean. Ice draft data from moored upward looking echosounders of the Beaufort Gyre Exploration Project and ice motion derived from trajectories of International Arctic Buoy Program buoys were combined to create directional sections of ice draft. Autocorrelation functions were created for each segment which were then combined to make a 2D autocorrelation function. The 2D FFT was taken of this in order to yield a 2D spectrum, from which isotropy and other spectral properties could be determined. The processing routine was tested on several synthetic test datasets and in each case produced the correct output. Two years of data from three moorings in the Beaufort all provided 2D spectra which showed weak anisotropy of the under-ice roughness. Error estimates were determined by Monte Carlo simulations. For each dataset, most of the variance of the underside morphology was contained in a wavenumber band between 0.001 and 0.01m-1 (100-1000m). There were no distinct, preferred wavelengths. Spectral levels ranged from 1.2 - 4.2 x 104 m2 for Mooring C (2004-2005) to 0.2 1.6 x 104 m2 for Mooring A (2004-2005). |
author2 |
NAVAL POSTGRADUATE SCHOOL MONTEREY CA |
format |
Text |
author |
McGeehan, Timothy P. |
author_facet |
McGeehan, Timothy P. |
author_sort |
McGeehan, Timothy P. |
title |
Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence |
title_short |
Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence |
title_full |
Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence |
title_fullStr |
Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence |
title_full_unstemmed |
Investigation of 2-Dimensional Isotropy of Under-Ice Roughness in the Beaufort Gyre and Implications for Mixed Layer Ocean Turbulence |
title_sort |
investigation of 2-dimensional isotropy of under-ice roughness in the beaufort gyre and implications for mixed layer ocean turbulence |
publishDate |
2008 |
url |
http://www.dtic.mil/docs/citations/ADA479954 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA479954 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Ice International Arctic Buoy Program permafrost Sea ice |
genre_facet |
Arctic Arctic Ocean Ice International Arctic Buoy Program permafrost Sea ice |
op_source |
DTIC |
op_relation |
http://www.dtic.mil/docs/citations/ADA479954 |
op_rights |
Approved for public release; distribution is unlimited. |
_version_ |
1766326202009649152 |