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1 Rutgers University Ocean Science Meeting - San Antonio, TX January, 2000

Evolution and Impact of an Upwind Coastal Jet Bob Chant 1 and Scott Glenn 1. 1 Rutgers University Ocean Science Meeting - San Antonio, TX January, 2000. Today’s Talk. Along Shore Wind Stress July 1998. dyne/cm 2. Ocean Currents in the LEO-15 Area on July 23, 1998 at 08:20 GMT.

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1 Rutgers University Ocean Science Meeting - San Antonio, TX January, 2000

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

  3. July 21, 1998 - 11:30 GMT ADCP Sections July 23, 1998 - 08:20 GMT Ocean Currents in the LEO-15 area

  4. 22o 18o 14o July 23 - 3rd Transect 22o 18o 30 20 10 0 -10 -20 -30 N o r t h S o u t h 14o cm/sec July 24 - 3rd Transect Along-shore Currents (color) and Temperature (contours)

  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 195 196 197 198 199 200 201 202 203 204 205 1.0 .75 .5 .25 0 -.25 -.5 -.75 -1.0 Wind Stress 195 196 197 198 199 200 201 202 203 204 205

  7. Along-Shore Surface and Bottom Transport and Along-shore Wind Stress dyne/cm2 m2/s 195 196 197 198 199 200 201 202 203 204 205 195 196 197 198 199 200 201 202 203 204 205 Cross-Shore Surface and Bottom Transport and Along-shore Wind Stress dyne/cm2 m2/s 195 196 197 198 199 200 201 202 203 204 205 Offshore Mooring

  8. m3/s *103 195 196 197 198 199 200 201 202 203 204 205 195 196 197 198 199 200 201 202 203 204 205 Transport Upshelf/Downshelf

  9. Node B Along-ShoreSurfaceand BottomTrasport and Along-Shore Wind Stress Node B dyne/cm2 m2/s 195 196 197 198 199 200 201 202 203 204 205 Node B Cross-ShoreSurfaceand BottomTrasport and Along-Shore Wind Stress dyne/cm2 m2/s 195 196 197 198 199 200 201 202 203 204 205

  10. Alongshore Transport at Node B m3/s m2/s 195 196 197 198 199 200 201 202 203 204 205 Wind Stress Along Shore dyne/cm2 Cross Shore 195 196 197 198 199 200 201 202 203 204 205

  11. 195 196 197 198 199 200 201 202 203 204 205

  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 = 3D Upwelling

  13. Distance (km) 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.

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