Why not look only at model output
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Why Not Look Only at Model Output?. Good Web Site to Explore VV. http://www.twisterdata.com/. Comparison of Various Forms of the Q-G Omega Equation. Classic (Two terms: differential vorticity advection, Laplacian of the thermal wind)

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Good web site to explore vv
Good Web Site to Explore VV

  • http://www.twisterdata.com/

Comparison of various forms of the q g omega equation
Comparison of Various Forms of the Q-G Omega Equation

  • Classic (Two terms: differential vorticity advection, Laplacian of the thermal wind)

  • The result is the difference between two large terms resulting in large truncation error.

  • Cannot estimate reliably from vorticity advection at a single level or from warm advection alone.

  • Using at a single level, best done at 500 hPa for strong events. Really need a 3D solution for an accurate answer.

    Trenberth/Sutcliffe formulation (advection of absolute vorticity by the thermal wind) is more accurate since no cancellation problem.

  • Q-Vector approach is the best in many ways

  • No cancellation problems

  • Includes deformation term

  • Provides insights into the lower branch of the ageostrophic circulation forced by the geostrophic forcing

  • Provides insights into frontogenesis

  • Allows rapid and intuitive graphical interpretation

Qg diagnostics online
QG Diagnostics Online

  • Classic approach: http://www.mmm.ucar.edu/people/tomjr/files/realtime/qg_diag/Omeg700Tot-NorAmer/res.html

  • Sutcliffe-Trenberth:http://www.mmm.ucar.edu/people/tomjr/files/realtime/qg_diag/OmegSutTren700Tot-NorAmer/res.html

  • Q-vector http://www.mmm.ucar.edu/people/tomjr/files/realtime/qg_diag/OmegQvec700Tot-NorAmer/res.html

Vertical motion
Vertical Motion

  • Can be as the complex sum of:

    • QG motions (relatively large scale and smooth)

    • Orographic forcing

    • Convective forcing

    • Gravity waves and other small-scale stuff

  • QG diagnostics helpful for seeing the big picture

But usually there is much more going on, so be VERY careful in application of simple jet streak model

  • Garp example…