EVAT 554 OCEAN-ATMOSPHERE DYNAMICS UPWELING AND DOWNWELLING; EKMAN TRANSPORT LECTURE 14 (Reference: Peixoto & Oort, Chapter 8,10)

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Presentation transcript:

EVAT 554 OCEAN-ATMOSPHERE DYNAMICS UPWELING AND DOWNWELLING; EKMAN TRANSPORT LECTURE 14 (Reference: Peixoto & Oort, Chapter 8,10)

Windstress and Circulation in the Upper Ocean Northern Hemisphere take H=2D E Mean transport is at right angles to surface wind (to the right in Northern Hemisphere) This transport occurs in a boundary layer of width Below this boundary layer we will generally have geostrophic flow...

Windstress and Circulation in the Upper Ocean Northern Hemisphere take H=2D E Coastal Downwelling

Windstress and Circulation in the Upper Ocean Northern Hemisphere take H=2D E Coastal Upwelling

Windstress and Circulation in the Upper Ocean Northern Hemisphere take H=2D E SUMMER COASTAL UPWELLING ALONG CALIFORNIA COAST

Windstress and Circulation in the Upper Ocean SUMMER COASTAL UPWELLING ALONG CALIFORNIA COAST SEA SURFACE TEMPERATURES

Windstress and Circulation in the Upper Ocean Northern Hemisphere take H=2D E Associated with a horizontal divergence of mass within the Ekman layer

Windstress and Circulation in the Upper Ocean Northern Hemisphere take H=2D E Associated with a horizontal divergence of mass within the Ekman layer But by continuity this horizontal divergence must be replaced at the base of the Ekman layer, Ekman Pumping

Windstress and Circulation in the Upper Ocean JJA Dynamic Topography Surface Windstress Ekman Transport piles up water in the subtropics!

Surface Windstress Windstress and Circulation in the Upper Ocean DJFJJA Note the relative amplitudes of variation with latitude!

Windstress and Circulation in the Upper Ocean

Equatorial Upwelling! f changes sign at the equator

Windstress and Circulation in the Upper Ocean Equatorial Upwelling! Within Ekman layer f changes sign at the equator

El Nino vs. La Nina equatorial upwelling

El Nino vs. La Nina coastal upwelling