1 / 20

Circulation, structure and dynamics of a buoyant coastal current.

Circulation, structure and dynamics of a buoyant coastal current. Bob Chant, Scott Glenn, Phillip Bogden American Meteorological Society Albuquerque New Mexico January 13-19, 2001. Warm. Fresh. Warm. Cold and Salty. Cold. Motivation

fierros
Download Presentation

Circulation, structure and dynamics of a buoyant coastal current.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Circulation, structure and dynamics of a buoyant coastal current. Bob Chant, Scott Glenn, Phillip Bogden American Meteorological Society Albuquerque New Mexico January 13-19, 2001 Warm Fresh Warm Cold and Salty Cold

  2. Motivation • Characterize Circulation and Dynamics of Coastal Current • Provides target for numerical modeling • Results can be used to assess accuracy of other techniques. • -Airborne altimetery • -Turbulence Sensors • -Modeling

  3. Pressure Gradient Coriolis Buoyant Coastal Current Warm Fresh Warm Cold and Salty Cold

  4. Towed ADCP/CTD data-July 28, 2000 Along-Shelf (color) and Cross-Shelf (vectors) Currents. Salinity (color) and Temperature (contour)

  5. . ADCP’s at 2,3,4,5 p-sensor & T-chain at 2 & 4 REMUS 2 REMUS 3 REMUS 4 REMUS 5

  6. Depth AverageFlow Sectionally Averaged Flow

  7. Along-shore flow fluctuations are in geostrophic balance

  8. Sectionally averaged Along-shore Analyze Flow during Southward Flows V < -10 cm/s

  9. Mean Flow when u < -10 cm/s f*v tb/rH ts/rH Residual 10 cm/s

  10. ~3 cm/20 km Cross Shore Flow Mean Flow (red) and Stratification (blue) (v < -10) 10 Along Shore Flow -10 10 10 -10 -10 10 4 4 -4 4 4 -4

  11. Barotropic pressure Gradient Baroclinic pressure Gradient Coriolis Warm Fresh Cold Cold

  12. Shear Equation Cross-Shore Momentum Equations Depth Averaged Depth Dependent

  13. Shear Stress Eddy Viscosity

  14. Conclusions • Surface and bottom Ekman layers are evident in “event-averaged” moored ADCP data. However, transport in the bottom layer is approximately one third of tb/rf. • Sectionally averaged fluctuating along-shore currents are geostrophically balanced. • In the near shore, weak stratification prevents bottom-stress from penetrating the entire water column. Mixing coefficients are strongest in the bottom mixed layer (10-2 m2/s), weakest in the interior (5*10-4 m2/s) and of intermediate values towards the surface (10-3 m2/s) • Fluctuating depth averaged and near bottom currents are highly • constrained by bathymetry. Surface currents are constrained by the coastline only within an internal Rossby radius from the coast.

  15. 20 cm/s 0.5 dyne/cm2

  16. Principle Components of fluctuating currents Surface-red Bottom-Blue Depth Average-Black

  17. Record Mean Flow f*u tb/rH Residual ts/rH 10 cm/s

  18. Surface Stress is Red Bottom Stress is Blue Along-Shelf Stress tb>ts (despite tb underestimate) Cross-Shelf Stress

More Related