The Atmosphere: Part 5: Large-scale motions

1. The Atmosphere:Part 5: Large-scale motions • Composition / Structure • Radiative transfer • Vertical and latitudinalheat transport • Atmospheric circulation • Climate modeling Suggested further reading: Holton, An Introduction to Dynamical Meteorology (Academic Press, 1979)

2. Calculated rad-con equilibrium T vs. observed T pole-to-equator temperature contrast too big in equilibrium state (especially in winter)

3. Zonally averaged net radiation Diurnally-averaged radiation Observed radiative budget Implied energy transport: requires fluid motions to effect the implied heat transport

4. Roles of atmosphere and ocean net ocean atmosphere Trenberth & Caron (2001)

5. Basic dynamical relationships Ω Equation of motion Ω Ωsinφ u φ Shallow atmosphere: } z - coordinates } p - coordinates

6. Basic dynamical relationships Ω Equation of motion Ω Ωsinφ u φ Shallow atmosphere: } z - coordinates

7. Basic dynamical relationships Ω Equation of motion Ω Ωsinφ u φ Shallow atmosphere: } z - coordinates } p - coordinates

8. Geostrophic balance

9. Geostrophic balance thermal wind shear balance

10. Rotating vs. nonrotating fluids

11. Rotating vs. nonrotating fluids

12. Rotating vs. nonrotating fluids Ω Ω f > 0 Ωsinφ u φ f = 0 f < 0

13. Atmospheric energetics:where does the energy of atmospheric motions come from? Flattening density/temperature surfaces always reduces potential energy

14. Atmospheric energetics:where does the energy of atmospheric motions come from? Flattening density/temperature surfaces always reduces potential energy Available potential energy inherent in density/temperature gradients

15. Atmospheric energetics:where does the energy of atmospheric motions come from? Flattening density/temperature surfaces always reduces potential energy Available potential energy inherent in density/temperature gradients In order to generate available potential energy, on average must heat where hot and cool where cold: < JT > > 0

16. Atmospheric energetics:where does the energy of atmospheric motions come from? Flattening density/temperature surfaces always reduces potential energy Available potential energy inherent in density/temperature gradients In order to generate available potential energy, on average must heat where hot and cool where cold: < JT > > 0 In order to release available potential energy (and generate motion), on average, warm air must rise, cold air sink: < wT > > 0