1. Evolution and Impact of an Upwind Coastal Jet
Bob Chant1 and Scott Glenn1
1Rutgers University
Ocean Science Meeting - San Antonio, TX
January, 2000

2. Along Shore Wind Stress July 1998 Ocean Currents in the LEO-15 Area
Today’s Talk
dyne/cm2
Ocean Currents in
the LEO-15 Area
on July 23, 1998
at 08:20 GMT

3. Ocean Currents in the LEO-15 area
ADCP Sections
July 21, :30 GMT
Ocean Currents in
the LEO-15 area
July 23, :20 GMT

4. Temperature (contours)
July rd Transect
Along-shore
Currents (color) and
Temperature (contours)
14o
22o
18o
July rd Transect 30 20 10
-10
-20
-30 N o r t h S u
cm/sec

5. July 23, 1998 - Detided Along Shelf Velocity
Downshelf Transport 31.7 km3/s
Downshelf Transport 29.4 km3/s
Downshelf Transport 22.6 km3/s

6. Transport upshelf/downshelf
Wind Stress
1.0
.75 .5
.25
-.25
-.5
-.75
-1.0

7. Along-Shore Surface and Bottom Transport and Along-shore Wind Stress
m2/s
dyne/cm2
Offshore
Mooring
Cross-Shore Surface and Bottom Transport and Along-shore Wind Stress
m2/s
dyne/cm2

8. Transport Upshelf/Downshelf
m3/s *103
Transport
Upshelf/Downshelf

9. Along-Shore Surface and Bottom Trasport and Along-Shore Wind Stress
Node B
Along-Shore Surface and
Bottom Trasport and
Along-Shore Wind Stress
Node B
dyne/cm2
m2/s
Node B
Cross-Shore Surface and
Bottom Trasport and
Along-Shore Wind Stress
dyne/cm2
m2/s

10. Alongshore
Transport
at Node B
m2/s
m3/s
Wind Stress
Along Shore
dyne/cm2
Cross Shore

12. Two Numbers
equal to the volume of a semicircle of fluid 20m deep and a diameter of 15 nm
If jet converges over a 50 km length
scale it would provide the additional
offshore transport observed at the
offshore mooring.
2D Upwelling Along-Shore Convergence = D Upwelling

13. What is the fate of the coastal jet as it impinges on shoaling
Distance (km)
What is the fate of
the coastal jet as it
impinges on shoaling
and rougher
topography?

14. Conclusions
1) AVHRR imagery reveals an upwelling center which translates down the coast and extends offshore.
2) Towed ADCP data revels an upwind-near-shore-jet during upwelling favorable conditions. The jet tends to have a mid depth maximum and resides in the center of spreading isopyncals.
3) The jet’s appearance was coincident with a maximum in the along shore wind stress and spins up within an inertial period.
4) Moored data indicate that off shore transport at the surface is consistent with Ekman transport prior to the jets appearance. However, as the near shore jet develops off shore transport exceeds the Ekman transport. We suggest that the increased offshore transport due to offshore transport of fluid in the Jet.
5) The volume of fluid transported by the jet is consistent with the volume of the upwelling center. We speculate that the evolution of the upwelling center and its offshore extent is related to the jet impinging on shoaling and rougher topography.