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
Coastal Upwelling
Coastal Upwelling
Coastal Upwelling
Coastal Upwelling
Coastal Upwelling
April 2000 CalCoFI Cruise
April 2000 CalCoFI Cruise
April 2000 CalCoFI Cruise
At smaller scales...
• Strong west winds
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
PelagicEcosystems
NUTS
CO2
Fixed Carbon
O2
h
Coastal Upwelling
• California Current
• April 1978
• AVHRR - SST
• CZCS Chlorophyll
SSTChl
Respiration & Remineralizati
on
remineralizers
h
CO2 O2
PlantsNUTS
Biological processes consume plants & O2 to make CO2 & nutrients
Euphotic Zone
Euphotic Zone – PP happens
Aphotic Zone - Respiration & Remineralization
Depth of Euphotic Zone is f(water clarity)
100% Light
1% Light
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
CalCoFI Light Profiles
% surface light
Depth
(m)
Secchi = 7 m
Secchi = 18 m
The Upwelling Conveyor Belt
Highest NUTS & CO2
High NUTSLow NUTS
High Chl Low ChlLower Chl
Sinking Flux of Carbon
CO2
CO2(aq) (CO2 + H2O)
photosynthesisrespiration
H2CO3
HCO3- + H+
oceanfood web
K1
K2
CO3-2
+ 2H+
Carbonate Chemistry
calcifiers
Increasing CO2: •Increases acidity (lowers pH)•Lowers CO3
- availability•Lowers CaCO3(s) saturation state
Acidification
Calderia & Wickett, Nature [2003]
Increasing CO2: •Increases acidity (lowers pH)•Lowers CaCO3(s) saturation state “”Multiple forms of CaCO3: aragonite, calcite, Mg-calcite with different solubility
More Seawater Chemistry
= [Ca2+][CO32-] / Ksp
Δ[CO32-] = [CO3
2-]obs - [CO32-]sat
-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
Biological Impacts
warm-water corals
cold-water corals
lobsters, crabs some plankton
pteropodsplanktonic snails
scallops, clams, oysters
Published by AAAS
R. A. Feely et al., Science 320, 1490 -1492 (2008)
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
Published by AAAS R. A. Feely et al., Science 320, 1490 -1492 (2008)
Fig. 2. Vertical sections of (A) temperature, (B) aragonite saturation, (C) pH, (D) DIC, and (E) pCO2 on transect line 5 off Pt George
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
