SAN FRANCISCO STATE UNIVERSITY                                             Meteorology 430

DEPARTMENT OF GEOSCIENCES                                                     Fall 2010

Final Examination

250 Points

Name _______________________________________________

1.         For questions involving use of equations or calculations, lay out all equations                                                            carefully, show all units, show all steps, number equations sequentially.

2.         For questions involving analysis or mapping techniques, use proper color                                                                 conventions, use proper mapping techniques (NO grease pencil on final copies).

3.         This examination is open book, open notes.

4.         Answer on separate sheets or on back of exam.

Part A. Application of QG-omega Equation (Map Set A) (140 points)

This question refers to the NAM 36 hour forecasts for 0000 UTC 12 December 2010:  (a) 500 mb Heights/500 mb Absolute Vorticity; (b)  the surface isobars overlaid with 1000-500 mb thickness contours for the same date and  time; (c) the absolute vorticity advection at 600 mb, 500 mb and 400 mb; and (d) the temperature advection at 500 mb.

You may assume that real wind is geostrophic and the real absolute vorticity is the same as the absolute geostophic vorticity.

The simplified quasigeostrophic omega equation is

(i) Qualitatively discuss the quasi-geostrophic diagnosed omega that would occur at point A at 500 mb on the basis of charts (a) and (b).   Be sure to discuss the contribution of each term, any assumptions you used and the whether the net forcing indicates upward, downward or indeterminate vertical motion.  This is comparable to what we have been doing or have done in Metr 201/400/698.  (50 points)

(ii) Qualitatively discuss discuss  quasi-geostrophic diagnosed omega that would occur at point A at 500 mb on the basis of charts (c) and (d).   Be sure to discuss the contribution of each term in detail.  This is a more accurate assessment of the nature of the forcing functions learned in Metr 430.  (50 pts)

(iii) Discuss if your Metr 400/698-level analysis (i) would be backed by your Metr 430-level analysis in (ii).  (20 points)

(iv) Discuss how the forcing in the vorticity advection term would be modulated by INCREASING the stability. (20 pts)

Part B.  Dines Compensation (Map Set B) (70 pts)

Attached find the WXP analyses of the 36 hour forecast NAM 300 mb convergence  and 500 mb vertical velocity for 00Z 12 December 2010.   Examine the pattern at the same location you used in Part A.

1.  Compute the 500 mb vertical velocity (in cm/s) that would be expected on the basis of Dines Compensation as expressed in the simplified continuity equation.

In this case,  you can assume that divergence at 300 mb is a good estimate of the net divergence in the layer from 500 mb to the tropopause at 300 mb and that 500 mb is the Level of Nondivergence.  The forecast 300 mb height is 888 dm and the forecast 500 mb height is 540 dm.

2.  Comment on the degree to which the actual vertical velocity field is consistent with your result.  Careful, the vertical velocity plot shows omega, not w.  However, I am only asking you to compare the general nature of your result to the actual NAM forecast vertical velocity.

Part C.  Interpretation of Cross-sections (Map Set C) (40 points)

You are given cross-sections of potential temperature, equivalent potential temperature and temperature at the latitude of San Diego stretching along a line of latitude to Florida.  You are  also given (a) a surface chart showing cross section location and fronts (assume that they are correct) and (c) soundings for San Diego, Albuquerque and Tallahassee at 12 UTC.

1.  Sketch in the position of the tropopause on the cross-section of potential temperature, and encircle areas where you would expect the value of the static stability parameter would be the greatest. (20 pts)

2.    Comment on how the cross-section of potential temperature is verified by the tropopause locations on (c). (20 pts)

Charts For

00 UTC December 12, 2010

Part A Charts

Part B Charts

Part C Charts--Cross-sections