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Dynamical Diagnosis: A Comparison of Quasigeostrophy and Ertel Potential Vorticity

  • John W. Nielsen-Gammon
  • David A. Gold
Chapter
Part of the Meteorological Monographs book series (METEOR, volume 33, No. 55)

Abstract

Advances in computer power, new forecasting challenges, and new diagnostic techniques have brought about changes in the way atmospheric development and vertical motion are diagnosed in an operational setting. Many of these changes, such as improved model skill, model resolution, and ensemble forecasting, have arguably been detrimental to the ability of forecasters to understand and respond to the evolving atmosphere. The use of nondivergent wind in place of geostrophic wind would be a step in the right direction, but the advantages of potential vorticity suggest that its widespread adoption as a diagnostic tool on the west side of the Atlantic is overdue. Ertel potential vorticity (PV), when scaled to be compatible with pseudopotential vorticity, is generally similar to pseudopotential vorticity, so forecasters accustomed to quasigeostrophic reasoning through the height tendency equation can transfer some of their intuition into the Ertel-PV framework. Indeed, many of the differences between pseudopotential vorticity and Ertel potential vorticity are consequences of the choice of definition of quasigeostrophic PV and are not fundamental to the quasigeostrophic system. Thus, at its core, PV thinking is consistent with commonly used quasigeostrophic diagnostic techniques.

Keywords

Geopotential Height Potential Vorticity Geostrophic Wind Vertical Vorticity Isentropic Surface 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Charney, J. G., and M. E. Stern, 1962: On the stability of internal baroclinic jets in a rotating atmosphere. J. Atmos. Sci., 19, 159–172.CrossRefGoogle Scholar
  2. Davis, C. A., 1992: Piecewise potential vorticity inversion. J. Atmos. Sci., 49, 1397–1411.CrossRefGoogle Scholar
  3. Dixon, M. A. G., A. J. Thorpe, and K. A. Browning, 2003: Layerwise attribution of vertical motion and the influence of potentialvorticity anomalies on synoptic development. Quart. J. Roy. Meteor. Soc., 129, 1761–1778.CrossRefGoogle Scholar
  4. Durran, D. R., and L. W. Snellman, 1987: The diagnosis of synopticscale vertical motion in an operational environment. Wea. Forecasting, 2, 17–31.CrossRefGoogle Scholar
  5. Errico, R. M., 1997: What is an adjoint model? Bull. Amer. Meteor. Soc., 78, 2577–2591.CrossRefGoogle Scholar
  6. Fehlmann, R., and H. C. Davies, 1997: Misforecasts of synoptic systems: Diagnosis by PV retrodiction. Mon. Wea. Rev., 125, 2247–2264.CrossRefGoogle Scholar
  7. Holton, J. R., 1992: An Introduction to Dynamic Meteorology. 3d ed. Academic Press, 511 pp.Google Scholar
  8. Hoskins, B. J., and M. A. Pedder, 1980: The diagnosis of middle latitude synoptic development. Quart. J. Roy. Meteor. Soc., 106, 707–719.CrossRefGoogle Scholar
  9. -, M. E. McIntyre, and A. Robertson, 1985: On the use and significance of isentropic potential vorticity maps. Quart. J. Roy. Meteor. Soc., 111, 887–946.CrossRefGoogle Scholar
  10. Juckes, M., 1999: The structure of idealized upper-tropospheric shear lines. J. Atmos. Sci., 56, 2830–2845.CrossRefGoogle Scholar
  11. Jusem, J. C., and R. Atlas, 1998: Diagnostic evaluation of vertical motion forcing mechanisms by using Q-vector partitioning. Mon. Wea. Rev., 126, 2166–2184.CrossRefGoogle Scholar
  12. Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437–471.CrossRefGoogle Scholar
  13. Keyser, D., M. J. Reeder, and R. J. Reed, 1988: A generalization of Petterssen’s frontogenesis function and its relation to the forcing of vertical motion. Mon. Wea. Rev., 116, 762–780.CrossRefGoogle Scholar
  14. -, B. D. Schmidt, and D. G. Duffy, 1992: Quasigeostrophic vertical motions diagnosed from along-and cross-isentrope components of the Q vector. Mon. Wea. Rev., 120, 731–741.CrossRefGoogle Scholar
  15. Massacand, A. C., H. Wernli, and H. C. Davies, 2001: Influence of upstream diabatic heating upon an Alpine event of heavy precipitation. Mon. Wea. Rev., 129, 2822–2828.CrossRefGoogle Scholar
  16. Mohebalhojeh, A. R., 2002: On shallow-water potential-vorticity inversion by Rossby-number expansions. Quart. J. Roy. Meteor. Soc., 128, 679–694.CrossRefGoogle Scholar
  17. Morgan, M. C., and J. W. Nielsen-Gammon, 1998: Using tropopause maps to diagnose midlatitude weather systems. Mon. Wea. Rev., 126, 2555–2579.CrossRefGoogle Scholar
  18. Muraki, D. J., C. Snyder, and R. Rotunno, 1999: The next-order corrections to quasigeostrophic theory. J. Atmos. Sci., 56, 1547–1560.CrossRefGoogle Scholar
  19. Nielsen-Gammon, J. W., 1995: Dynamical conceptual models of upper-level mobile trough formation: Comparison and application. Tellus, 47A, 705–721.Google Scholar
  20. -, 2001: A visualization of the global dynamic tropopause. Bull. Amer. Meteor. Soc., 82, 1151–1167.CrossRefGoogle Scholar
  21. -, and R. J. Lefevre, 1996: Piecewise tendency diagnosis of dynamical processes governing the development of an upper-tropospheric mobile trough. J. Atmos. Sci., 53, 3120–3142.CrossRefGoogle Scholar
  22. -, and D. A. Gold, 2008: Potential vorticity diagnosis in the quasigeostrophic and nonlinear balance systems. J. Atmos. Sci., 65, 172–188.CrossRefGoogle Scholar
  23. Orlanski, I., and J. Sheldon, 1993: A case of downstream baroclinic development over western North America. Mon. Wea. Rev., 121, 2929–2950.CrossRefGoogle Scholar
  24. Pedlosky, J., 1987: Geophysical Fluid Dynamics. 2d ed. Springer-Verlag, 710 pp.Google Scholar
  25. Sanders, F., 1971: Analytic solutions of the nonlinear omega and vorticity equations for a structurally simple model of disturbances in the baroclinic westerlies. Mon. Wea. Rev., 99, 393–407.CrossRefGoogle Scholar
  26. -, and B. J. Hoskins, 1990: An easy method for estimation of Q-vectors from weather maps. Wea. Forecasting, 5, 346–353.CrossRefGoogle Scholar
  27. Sutcliffe, R. C., 1947: A contribution to the problem of development. Quart. J. Roy. Meteor. Soc., 73, 370–383.CrossRefGoogle Scholar
  28. Tan, Z.-M., F. Zhang, R. Rotunno, and C. Snyder, 2004: Mesoscale predictability of moist baroclinic waves: Experiments with parameterized convection. J. Atmos. Sci., 61, 1794–1804.CrossRefGoogle Scholar
  29. Thorpe, A. J., 1986: Synoptic-scale disturbances with circular symmetry. Mon. Wea. Rev., 114, 1384–1389.CrossRefGoogle Scholar
  30. -, and C. H. Bishop, 1995: Potential vorticity and the electrostatics analogy: Ertel—Rossby formulation. Quart. J. Roy. Meteor. Soc., 121, 1477–1495.Google Scholar
  31. Trenberth, K. E., 1978: On the interpretation of the diagnostic quasigeostrophic omega equation. Mon. Wea. Rev., 106, 131–137.CrossRefGoogle Scholar
  32. Vallis, G. K., 1996: Potential vorticity inversion and balanced equations of motion for rotating and stratified flows. Quart. J. Roy. Meteor. Soc., 122, 291–322.CrossRefGoogle Scholar
  33. Warn, T., O. Bokhove, T. G. Shepherd, and G. K. Vallis, 1995: Rossby number expansions, slaving principles, and balanced dynamics. Quart. J. Roy. Meteor. Soc., 121, 723–739.CrossRefGoogle Scholar

Copyright information

© American Meteorological Society 2008

Authors and Affiliations

  1. 1.Department of Atmospheric SciencesTexas A&M UniversityCollege StationUSA

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