Accession Number : ADA586616


Title :   Surface Wave Effects on High-Frequency Currents Over a Shelf Edge Bank


Descriptive Note : Journal article


Corporate Author : NAVAL RESEARCH LAB STENNIS DETACHMENT STENNIS SPACE CENTER MS


Personal Author(s) : Wijesekera, H W ; Wang, D W ; Teague, W J ; Jarosz, E ; Rogers, W E ; Fribance, D B ; Moum, J N


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a586616.pdf


Report Date : Aug 2013


Pagination or Media Count : 22


Abstract : Several acoustic Doppler current profilers and vertical strings of temperature, conductivity, and pressure sensors, deployed on and around the East Flower Garden Bank (EFGB), were used to examine surface wave effects on high-frequency flows over the bank and to quantify spatial and temporal characteristic of these high-frequency flows. The EFGB, about 5-km wide and 10-km long, is located about 180-km southeast of Galveston, Texas, and consists of steep slopes on southern and eastern sides that rise from water depths over 100 m to within 20 m of the surface. Three-dimensional flows with frequencies ranging from 0.2 to 2 cycles per hour (cph) were observed in the mixed layer when wind speed and Stokes drift at the surface were large. These motions were stronger over the bank than outside the perimeter. The squared vertical velocity w2 was strongest near the surface and decayed exponentially with depth, and the e-folding length of w2 was 2 times larger than that of Stokes drift. The 2-h-averaged w2 in the mixed layer, scaled by the squared friction velocity, was largest when the turbulent Langmuir number was less than unity and the mixed layer was shallow. It is suggested that Langmuir circulation is responsible for the generation of vertical flows in the mixed layer, and that the increase in kinetic energy is due to an enhancement of Stokes drift by wave focusing. The lack of agreement with open-ocean Langmuir scaling arguments is likely due to the enhanced kinetic energy by wave focusing.


Descriptors :   *CONTINENTAL SHELVES , *KINETIC ENERGY , *OCEAN CURRENTS , *SURFACE WAVES , AIR WATER INTERACTIONS , BANKS(WATERWAYS) , BUOYANCY , COASTAL REGIONS , CONTINENTAL SLOPES , DOPPLER SYSTEMS , MOMENTUM TRANSFER , PROBABILITY DISTRIBUTION FUNCTIONS , TEXAS , TURBULENT BOUNDARY LAYER , VELOCITY , WIND


Subject Categories : Physical and Dynamic Oceanography
      Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE