The Atmosphere:Part 7: The Extratropical Circulation

• Composition / Structure

• Radiative transfer

• Vertical and latitudinal heat transport• Atmospheric circulation• Climate modeling

Suggested further reading:

Holton, An Introduction to Dynamical Meteorology (Academic Press, 1979)

Roles of atmosphere and ocean

Trenberth & Caron (2001)

net

ocean

atmosphere

Circulation in our 2D model

Ω

f = 0

f > 0

f < 0

Hadley Cell

T = Te

Plenty of APE in middle and high latitudes

Experiment on rotating table with imposed temperature gradient

hot water bathcold water bath

working fluid

rotating turntable

Rapid rotation — baroclinic instability

tropics — direct overturning extratropics — eddy transport

Atmospheric heat transport

Atmospheric heat transport

Warm air upward and poleward

Cold air downward and equatorward} Efficient poleward heat transport

Roles of atmosphere and ocean

Trenberth & Caron (2001)

net

ocean

atmosphere

Angular momentum budget

Low level westerlies — loss of

AM to surface through friction

Low level easterlies — gain of

AM from surface through friction

Atmospheric angular momentum transport

Observed angular momentum transport total

transient eddies

stationary eddies

(mean circulation)

Eddy angular momentum transport