Real-Time QG Diagnostics

The intended purpose of the real-time analyses and forecasts of the quasi-geostrophic (QG) diagnostic equations web page is to provide an interactive tool that can be used to enhance classroom education and/or weather discussions in both the academic and operational environment by providing visualizations of core QG dynamical equations.

The calculations and visualizations created here (using NCAR Command Language version 6.1.0) are produced by the Department of Hydrology and Atmospheric Sciences at The University of Arizona. All fields are computed using 12-hourly pressure-level data from the Canadian Meteorological Centre (CMC) Global Deterministic Forecast System forecasts available in GRIB2 format at 0.6x0.6 degree latitude-longitude grid spacing. The raw CMC global forecasts are smoothed using a 9-point local smoother run 80 times to produce cleaner results for the QG diagnostics. A detailed description of the fields displayed on each set of images is provided in the Users' Guides and as captions on the animations themselves. While every attempt is made to keep the images up-to-date, it is possible that there will be interruptions to the image generation services as system updates occur.

Each animation provided at the links below includes a 20-day analysis archive and the most recent forecast out to 144 hours. Images older than 20 days are not retained. The old version of the real-time QG diagnostics website is available here through the end of 2018.

1. Sutcliffe Development Theory: (click here for Users' Guide)

1000 hPa height, geostrophic relative vorticity, and 1000-500 hPa thickness
1000 hPa height, 1000-500 hPa thickness, and thermal vorticity
1000 hPa height, 1000-500 hPa thickness, and total RHS
1000 hPa height, 1000-500 hPa thickness, and steering term (A)
1000 hPa height, 1000-500 hPa thickness, and amplification term (B)
1000 hPa height, 1000-500 hPa thickness, and Beta term (C)

 

2. Petterssen Development Equation: (click here for Users' Guide)

500 hPa height and geostrophic absolute vorticity
700 hPa height, temperature, and vertical motion
1000 hPa height, 1000-500 hPa thickness, and total RHS
1000 hPa height, 500 hPa height, and absolute vorticity advection term (A)
1000 hPa height, 1000-500 hPa thickness, and Laplacian of thickness advection term (B)
1000 hPa height, 850-500 hPa mean ascent, and Laplacian of vertical motion term (C)

 

3. Height Tendency Equation: (click here for Users' Guide)

500 hPa height, geostrophic wind, and geostrophic absolute vorticity
300 hPa height, temperature, geostrophic wind, and temperature advection
700 hPa height, temperature, geostrophic wind, and temperature advection
500 hPa height and total RHS (traditional form)
500 hPa height and propagation term (A) (traditional form)
500 hPa height and amplification term (B) (traditional form)
500 hPa height and QGPV
500 hPa height and total RHS (QGPV form)

 

4. Omega Equation: (click here for Users' Guide)

700 hPa height and total RHS (traditional form)
700 hPa height and differential vorticity advection term (A) (traditional form)
700 hPa height, temperature, and Laplacian of temperature advection term (B) (traditional form)
700 hPa height, geostrophic relative vorticity, and 900-500 hPa thickness
700 hPa height, 900-500 hPa thickness, and total RHS (Trenberth form)
700 hPa height, 900-500 hPa thickness, and vorticity advection by thermal wind term (A) (Trenberth form)
700 hPa height, 900-500 hPa thickness, and planetary vorticity advection by thermal wind term (B) (Trenberth form)
700 hPa height, 900-500 hPa thickness, and deformation term (C) (Trenberth form)
700 hPa height, temperature, Q-vectors, and total RHS (Q-vector form)
700 hPa height, temperature, and Q/Qn/Qs intercomparison

 

5. QG energetics: [Lackmann (2011) pp. 57-65]

500 hPa height and height perturbation from zonal mean
500 hPa height and geostrophic wind perturbation from zonal mean
500 hPa height perturbation from zonal mean and ageostrophic geopotential flux vectors and divergence

 

6. References:

Bluestein, H. B., 1992: Principles of Kinematics and Dynamics. Vol. I. Synoptic-Dynamic Meteorology in Midlatitudes. Oxford University Press, 431 pp.
Carlson, T. N., 1998: Mid-Latitude Weather Systems. Amer. Meteor. Soc., 507 pp.
Hakim, G. J., L. F. Bosart, and D. Keyser, 1995: The Ohio Valley wave-merger cyclogenesis event of 25-26 January 1978. Part I: Multiscale case study. Mon. Wea. Rev., 123, 2663-2692.
Hoskins, B. J., I. Draghici, and H. C. Davies, 1978: A new look at the omega equation. Quart. J. Roy. Meteor. Soc., 104, 31-38.
Keyser, D., M. J. Reeder, and R. J. Reed, 1988: A generalization of Petterssen’s frontogenesis function and its relation to the forcing for vertical motion. Mon. Wea. Rev., 116, 762-780.
Keyser, D., 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.
Martin, J. E., 1999a: Quasigeostrophic forcing of ascent in the occluded sector of cyclones and the Trowal airstream. Mon. Wea. Rev., 127, 70-88.
Martin, J. E., 1999b: The separate roles of geostrophic vorticity and deformation in the midlatitude occlusion process. Mon. Wea. Rev., 127, 2404-2418.
Martin, J. E., 2006: Mid-Latitude Atmospheric Dynamics: A First Course. John Wiley & Sons Ltd., 324 pp.
Lackmann, G., 2011: Midlatitude Synoptic Meteorology: Dynamics, Analysis, and Forecasting. Amer. Meteor. Soc., 345 pp.
Petterssen, S., 1956: Motion and Motion Systems. Vol. I. Weather Analysis and Forecasting. McGraw-Hill, 428 pp.
Sutcliffe, R. C., 1947: A contribution to the problem of development. Quart. J. Roy. Meteor. Soc., 73, 370-383.
Sutcliffe, R. C., and A. G. Forsdyke, 1950: The theory and use of upper air thickness patterns in forecasting. Quart. J. Roy. Meteor. Soc., 76, 189-217.
Trenberth, K. E., 1978: On the interpretation of the diagnostic quasi-geostrophic omega equation. Mon. Wea. Rev., 106, 131-137.