Introduction to Ocean Circulation - Geography

163 • Wind-driven circulation of major gyres

& surface currents• Buoyancy-driven circulation linking the

major gyres & the global conveyor belt• Coastal circulations & land-ocean

interactions• Build from physical principles (w/out

math)

Approach

• First principles do “work”

• Build descriptions from first principles

• Do not bludgeon students with calculus

• Work with available data sets

Why do we care?

• Climate– Global heat & water cycles– Weather & weather/climate prediction

• Global biogeography & biogeochemistry– Species ranges & adaptation to global change

– Fossil fuel CO2 sequestration

• Marine resources– Renewable (fisheries)– Non-renewable (oil, etc.)

Global Heat Transport

How can it be constant?

Global Heat Transport

Global Heat Transport

1015 W = 1 Petawatt

El Niño

El Niño

El Niño

Bigeography

Bigeographical Boundaries

Bigeography

CO2 Sequestration

It’s gotta go somewhere...

CO2 Sequestration

This is where.

Climate & Fish

Pacific Decadal Oscillation Warm phase - southern Cool phase - northern

We’re now in a cool phase…

Introduction to Ocean Circulation - Geography

163 • Wind-driven circulation of major gyres

& surface currents

• Buoyancy-driven circulation linking the major gyres & the global conveyor belt

• Coastal circulations & land-ocean interactions

Wind-Driven Gyres

Global Ocean Circulation

Global Wind Climate

Conveyor Belt

Net Air-Sea Heat Flux

Coastal Upwelling

Coastal Upwelling

Coastal Upwelling

July 1992AVHRR Ch 4

Scales

• Ocean basins are wide & shallow – Typical scales are 104 km across and 5 km deep

– “Spit on a basketball”

• Aspect ratio has important implications– Horizontal velocities are >> vertical velocities

– Horizontal property changes are << vertical ones

Hyposgraphic Curve

Atlantic Temperature

eWOCE gallery – www.ewoce.org

Atlantic Salinity

Atlantic Oxygen

Atlantic Phosphate

Summary

• Importance of large-scale ocean circulation– climate, biogeochemistry, marine resources

• Characteristic “Types” of Ocean Circulation – Patterns of circulation can be generalized for different

regions

– Suggests that dynamical processes are the same

– Wind-driven, Buoyancy-driven & Coastal

• Scales - “spit on a basketball”