Moving quasigeostrophic theory into the 21st century

Quasigeostrophic (QG) theory has been a central part of synoptic scale meteorology for well over half a century. It was used quantitatively in the early days of numerical weather prediction and has been applied qualitatively for decades, in one form or another, in operational weather forecasting and research in synoptic scale dynamics. Moreover, QG theory is a staple in nearly all, if not all, dynamic meteorology courses at both the undergraduate and graduate level.

Unfortunately, most applications of QG theory in operational forecasting, research studies and meteorological education has changed little during this time. One notable exception is the use of Q-vectors to diagnose vertical motions rather than evaluating the forcing associated with temperature and vorticity advection. However, the implementation of high resolution numerical analyses and forecasts has made both of these older application methods difficult, if not impossible, to implement.

The increase in computing power that has produced these high resolution data sets has also led to the capability of applying QG theory using more pure quantitative procedures. This has been manifest at the National Weather Service Forecast Office in Denver/Boulder through the use of a complete QG analysis package that goes well beyond the typical applications of the theory. The package is run on all of the numerical weather prediction data received at the office and provides full three dimensional numerical solutions to the QG omega, height tendency and Zwack-Okossi development equations. In addition, a variety of other QG related fields are computed including deformation, static stability tendency, frontogenesis, and others. The package allows forecasters to easily diagnose the synoptic scale dynamics both in the analyses and forecasts. Furthermore, although not yet implemented, the package could easily be used in the classroom to revolutionize the way meteorology students are introduced to QG theory by avoiding the relatively large number of assumptions, some of which are rather questionable, that are usually considered to make the presentation more tractable.

This paper will discuss the features of this package, share some of the insights that have been gained through its operational use, and suggest ways that the package could be used in the classroom.