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EVAT 554 OCEAN-ATMOSPHERE DYNAMICS

Learn about thermally-driven pole-equator circulation, Hadley cells, and extratropical circulation patterns in the lecture series on atmospheric dynamics. Explore the dynamics of surface pressure systems, meridional circulation, and the role of geostrophic and thermal winds.

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EVAT 554 OCEAN-ATMOSPHERE DYNAMICS

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  1. EVAT 554OCEAN-ATMOSPHERE DYNAMICS LARGE-SCALE ATMOSPHERIC CIRCULATION (CONT) LECTURE 9 (Reference: Peixoto & Oort, Chapter 3,7)

  2. Pole Equator THERMALLY-DRIVEN CIRCULATION Approximate circulation as steady, linear, two-dimensional (meridional-vertical plane) HADLEY CELL CIRCULATION THERMALLY-DIRECT CIRCULATION FOR AN IDEALIZED NON-ROTATING EARTH

  3. Pole Equator THERMALLY-DRIVEN CIRCULATION Approximate circulation as steady, linear, two-dimensional (meridional-vertical plane) WHAT ABOUT EXTRATROPICS? THERMALLY-DIRECT CIRCULATION FOR AN IDEALIZED NON-ROTATING EARTH

  4. Ascending Air Ascending Air Descending Air Descending Air High Pressure High Pressure Low Pressure Low Pressure THERMALLY INDIRECT CIRCULATION WARM COLD THERMALLY-DIRECT CIRCULATION COLD WARM

  5. HADLEY CELLS ARE THERMALLY DIRECT CIRCULATIONS… As are the (weak) polar cells Latitude Low High Low High Low S N Surface Pressure Systems 0 30 30 60 60 ‘FERREL CELLS’ ARE THERMALLY-INDIRECT CIRCULATIONS MERIDIONAL CIRCULATION PATTERNS

  6. HORIZONTAL ATMOSPHERIC CIRCULATION Cloud and Precipitation Occur in Areas of Surface Convergence and Rising Motion

  7. GLOBAL ATMOSPHERIC CIRCULATION January July There are important seasonal changes in the semi-permanent features of the surface atmospheric circulation ITCZ migrates with Sun, but lags it...

  8. GLOBAL ATMOSPHERIC CIRCULATION January July There are corresponding seasonal changes in the upper air (e.g. 500 mb) circulation

  9. S N 0 30 30 60 60 GLOBAL ATMOSPHERIC CIRCULATION Vertical Atmospheric Circulation Latitude Low High Low High Low Surface Pressure Systems Zonally-averaged ps

  10. S N 0 30 30 60 60 GLOBAL ATMOSPHERIC CIRCULATION Westerly Surface Wind Systems Easterly Surface Pressure Systems Zonally-averaged ps

  11. GLOBAL ATMOSPHERIC CIRCULATION east-west component of wind at surface consistent with Geostrophic Balance  (westerlies)  (easterlies) L’Hopital’s rule Why should there be any easterlies here??

  12. GLOBAL ATMOSPHERIC CIRCULATION Geostrophic Balance Hydrostatic Balance Combine these THERMAL WIND

  13. THERMAL WIND THERMAL WIND

  14. MERIDIONAL-VERTICAL CIRCULATION Continuity Steady state Streamfunction

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