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Coastal Upwelling

Coastal Upwelling. Equatorward winds along a coastline lead to offshore Ekman transport Mass conservation requires these waters replaced by cold, denser waters Brings nutrients into surface waters creating blooms Creates dynamic height gradients - currents. Coastal Upwelling.

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Coastal Upwelling

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  1. Coastal Upwelling • Equatorward winds along a coastline lead to offshore Ekman transport • Mass conservation requires these waters replaced by cold, denser waters • Brings nutrients into surface waters creating blooms • Creates dynamic height gradients - currents

  2. Coastal Upwelling

  3. Coastal Upwelling

  4. Coastal Upwelling

  5. Coastal Upwelling

  6. Coastal Upwelling

  7. Coastal Upwelling

  8. April 2000 CalCoFI Cruise

  9. April 2000 CalCoFI Cruise

  10. April 2000 CalCoFI Cruise

  11. At smaller scales... • Strong west winds

  12. Pelagic Ecosystems Ocean Biogeochemistry in a Nutshell • Light energy drives the net fixation of carbon • Within the euphotic zone, nutrients & CO2 produce CO2 & fixed carbon • Below the euphotic zone, the rxn’s reverse hn NUTS Fixed Carbon CO2 O2

  13. Coastal Upwelling • California Current • April 1978 • AVHRR - SST • CZCS Chlorophyll Chl SST

  14. Respiration & Remineralization hn CO2 O2 remineralizers NUTS Plants Biological processes consume plants & O2 to make CO2 & nutrients

  15. Euphotic Zone 1% Light 100% Light Euphotic Zone – PP happens Aphotic Zone - Respiration & Remineralization Depth of Euphotic Zone is f(water clarity)

  16. Euphotic Zone • Defined as the depth where the light = 1% of the surface value • A function of plant biomass or chlorophyll concentration • Varies from 10 to 130 m • Typically, Zeu = 3 * Secchi depth

  17. CalCoFI Light Profiles Secchi = 7 m Depth (m) Secchi = 18 m % surface light

  18. The Upwelling Conveyor Belt Lower Chl High Chl Low Chl Low NUTS High NUTS Sinking Flux of Carbon Highest NUTS & CO2

  19. Carbonate Chemistry CO2 CO2(aq) (CO2 + H2O) H2CO3 K1 photosynthesis respiration HCO3-+ H+ K2 ocean food web CO3-2+ 2H+ calcifiers

  20. Acidification • Increasing CO2: • Increases acidity (lowers pH) • Lowers CO3- availability • Lowers CaCO3(s) saturation state Calderia & Wickett, Nature [2003]

  21. More Seawater Chemistry • Increasing CO2: • Increases acidity (lowers pH) • Lowers CaCO3(s) saturation state “” • Multiple forms of CaCO3: aragonite, calcite, Mg-calcite with different solubility = [Ca2+][CO32-] / Ksp Δ[CO32-] =[CO32-]obs - [CO32-]sat

  22. warm-water corals Biological Impacts • -Shell forming plants & animals • reduced shell formation (calcification) • lower reproduction & growth rates • -Habitat loss (reefs) • -Less food for predators • humans, fish, whales • -Possible negative effects on larvae lobsters, crabs some plankton cold-water corals pteropods planktonic snails scallops, clams, oysters

  23. Fig. 1. Distribution of the depths of the undersaturated water (aragonite saturation < 1.0; pH < 7.75) on the continental shelf of western North America from Queen Charlotte Sound, Canada, to San Gregorio Baja California Sur, Mexico R. A. Feely et al., Science 320, 1490 -1492 (2008) Published by AAAS

  24. Fig. 2. Vertical sections of (A) temperature, (B) aragonite saturation, (C) pH, (D) DIC, and (E) pCO2 on transect line 5 off Pt George Published by AAAS R. A. Feely et al., Science 320, 1490 -1492 (2008)

  25. Review • Wind stress along coasts leads to divergence of surface Ekman transport • This drives to coastal upwelling and forms a coastal jet • This drives the productivity of eastern boundary currents • Important for acidification of the coastal ocean

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