Chapter 10

Atmosphere Ocean Interactions Global Winds and Surface Ocean Currents Ocean surface dragged by wind, basins react to high pressure circulation forming gyres Cold current, flowing north to south, on west side of continent Warm current, flowing south to north, on east side of continent Oceanic front

Stepped Art Fig , p. 273

Atmosphere Ocean Interactions Upwelling Ekman spiral, Ekman transport Water moving away from the coast causes upwelling

Fig , p. 273

Fig , p. 273

Fig , p. 274

Atmosphere Ocean Interactions El Nino and the Southern Oscillation El Nino: irregular warm episode off west coast of South America Southern Oscillation: rise in pressure over W Pacific, fall in the E Pacific, equatorial countercurrent ENSO La Nina (cold waters off the coast of South america indicating strong upwelling) teleconnections

Conditions Fall For latest update see link below. The Pacific Decadal Oscillation is also presently in its cool phase so colder than average and wetter than average winter is expected this coming winter.

Fall 2010 values are negative indicating a significant La Nina this Fall.

Atmosphere Ocean Interactions Pacific Decadal Oscillation Reversal in Pacific Ocean temperatures Warm = more Pacific storms Cool = cool, wet NW North America, wetter over the Great Lakes, salmon fisheries decline

Atmosphere Ocean Interactions North Atlantic Oscillation Reversal of pressure in North Atlantic Ocean affecting weather in Europe and eastern coast of North America Positive = strong Westerlies, storms in N Europe, wet and mild in eastern US Negative = wet southern Europe and Mediterranean, cold and dry in eastern US

Atmosphere Ocean Interaction Arctic Oscillation Closely related to NAO Pressure changes between Arctic and adjacent southern areas causes changes upper-level winds Positive = mild winter in US and W Europe Negative = cold US, cold dry Europe, wet Mediterranean