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