In:
Journal of Atmospheric and Oceanic Technology, American Meteorological Society, Vol. 31, No. 5 ( 2014-05), p. 1128-1150
Abstract:
Measurements of ocean microstructure are made in the turbulent Faroe Bank Channel overflow using a turbulence instrument attached to an underwater glider. Dissipation rate of turbulent kinetic energy ε is measured using airfoil shear probes. A comparison is made between 152 profiles from dive and climb cycles of the glider during a 1-week mission in June 2012 and 90 profiles collected from the ship using a vertical microstructure profiler (VMP). Approximately one-half of the profiles are collocated. For 96% of the dataset, measurements are of high quality with no systematic differences between dives and climbs. The noise level is less than 5 × 10 −11 W kg −1 , comparable to the best microstructure profilers. The shear probe data are contaminated and unreliable at the turning depth of the glider and for U / u t 〈 20, where U is the flow past the sensor, u t = ( ε / N ) 1/2 is an estimate of the turbulent velocity scale, and N is the buoyancy frequency. Averaged profiles of ε from the VMP and the glider agree to better than a factor of 2 in the turbulent bottom layer of the overflow plume, and beneath the stratified and sheared plume–ambient interface. The glider average values are approximately a factor of 3 and 9 times larger than the VMP values in the layers defined by the isotherms 3°–6° and 6°–9°C, respectively, corresponding to the upper part of the interface and above. The discrepancy is attributed to a different sampling scheme and the intermittency of turbulence. The glider offers a noise-free platform suitable for ocean microstructure measurements.
Type of Medium:
Online Resource
ISSN:
0739-0572
,
1520-0426
DOI:
10.1175/JTECH-D-13-00221.1
Language:
Unknown
Publisher:
American Meteorological Society
Publication Date:
2014
detail.hit.zdb_id:
2021720-1
detail.hit.zdb_id:
48441-6
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