Turbulent Transport from an Arctic Lead: A Large-Eddy Simulation

The upward transfer of heat from ocean to atmosphere is examined for an Arctic 'lead,' a break in the Arctic ice which allows contact between the cold atmosphere and the relatively warm ocean. We employ a large-eddy model to compute explicitly the three dimensional turbulent response of th...

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Bibliographic Details
Main Authors: Glendening, John W., Burk, Stephen D.
Other Authors: NAVAL OCEANOGRAPHIC AND ATMOSPHERIC RESEARCH LAB STENNIS SPACE CENTER MS
Format: Text
Language:English
Published: 1992
Subjects:
Meteorology
Physical and Dynamic Oceanography
Thermodynamics
Fluid Mechanics
*HEAT TRANSFER
*TURBULENCE
*ATMOSPHERIC MOTION
*EDDIES(FLUID MECHANICS)
SIMULATION
AIR WATER INTERACTIONS
ADVECTION
ARCTIC REGIONS
ATMOSPHERE MODELS
HEAT FLUX
PLUMES
REPRINTS
WIND VELOCITY
BOUNDARY LAYER
UPDRAFTS
MESOSCALE
ARCTIC LEADS
PE61153N
WU14411A
Arctic
Online Access:http://www.dtic.mil/docs/citations/ADA254396
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA254396
Description
Summary:The upward transfer of heat from ocean to atmosphere is examined for an Arctic 'lead,' a break in the Arctic ice which allows contact between the cold atmosphere and the relatively warm ocean. We employ a large-eddy model to compute explicitly the three dimensional turbulent response of the atmosphere to a lead of 200 m width. The surface heat flux creates a turbulent 'plume' of individual quasi-random eddies, not a continuous updraft, which penetrate into the stable atmosphere and transport heat upward. Maximum updraft velocities and turbulence occur downwind of the lead rather than over the lead itself, because the development time of an individual thermal eddy is longer than its transit time across the lead. The affected vertical region, while shallow over the lead itself, grows to a height of 65 m at 600 m downwind of the lead; beyond that, the depth of the turbulent region decreases as the eddies weaken. The maximum vertical turbulent heat flux occurs at the downwind edge of the lead, beyond which a relative maximum extends upward into the plume. Negative surface heat flux immediately downwind of the lead creates a growing stable layer, but above that internal boundary layer the turbulent heat flux is still positive. Updraft maxima are typically 28 cm/s, but compensating downdrafts result in time-averaged vertical velocities of less than 1 cm/s in the plume. Conditional sampling separates the updraft and downdraft contributions. Formulas for the horizontal eddy development distance and for the vertical plume penetration height are presented. Published in Boundary-Layer Meteorology, v59, p315-339, 1992.

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