Record Details
Measurements of Form and Frictional Drags over a Rough Topographic Bank
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Measurements of Form and Frictional Drags over a Rough Topographic Bank |
| Names |
Wijesekera, H. W.
(creator) Jarosz, E. (creator) Teague, W. J. (creator) Wang, D. W. (creator) Fribance, D. B. (creator) Moum, J. N. (creator) Warner, S. J. (creator) |
| Date Issued | 2014-09 (iso8601) |
| Note | To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American Meteorological Society and can be found at: http://journals.ametsoc.org/loi/phoc. |
| Abstract | Pressure differences across topography generate a form drag that opposes the flow in the water column, and viscous and pressure forces acting on roughness elements of the topographic surface generate a frictional drag on the bottom. Form drag and bottom roughness lengths were estimated over the East Flower Garden Bank (EFGB) in the Gulf of Mexico by combining an array of bottom pressure measurements and profiles of velocity and turbulent kinetic dissipation rates. The EFGB is a coral bank about 6 km wide and 10 km long located at the shelf edge that rises from 100-m water depth to about 18m below the sea surface. The average frictional drag coefficient over the entire bank was estimated as 0.006 using roughness lengths that ranged from 0.001 cm for relatively smooth portions of the bank to 1–10 cm for very rough portions over the corals. The measured form drag over the bank showed multiple time-scale variability. Diurnal tides and low-frequency motions with periods ranging from 4 to 17 days generated form drags of about 2000 N m⁻¹ with average drag coefficients ranging between 0.03 and 0.22, which are a factor of 5–35 times larger than the average frictional drag coefficient. Both linear wave and quadratic drag laws have similarities with the observed form drag. The form drag is an important flow retardation mechanism even in the presence of the large frictional drag associated with coral reefs and requires parameterization. |
| Genre | Article |
| Topic | Tidal flow |
| Identifier | Wijesekera, H. W., Jarosz, E., Teague, W. J., Wang, D. W., Fribance, D. B., Moum, J. N., & Warner, S. J. (2014). Measurements of form and frictional drags over a rough topographic bank. Journal of Physical Oceanography, 44(9), 2409-2432. doi:10.1175/JPO-D-13-0230.1 |
