EAS 485 Assignment 2: Upper Air Analysis for 00Z-12Z 25 April 2008

Due: Friday, February 20

Use the attached Upper-Air Charts to find support for surface high pressure, low pressure, the fronts, and where lift is most likely according to the following:

1. Use the 250 mb, 300 mb, and the maximum wind level convergence plots to determine the following.

1. Is this jet stream level? Use Thermal Wind to confirm or deny
   1. If so, describe jet streak circulations to provide lift for precipitation and/or convergence-divergence above surface highs and lows, pressure fall and rise centers.
2. Use the ageostrophic wind plots to support the existence of any jet streak circulation (refer to ageostrophic wind plots from Moore and VanKnowe (1992)

2. Use the 500 mb analysis, the 500 mb vorticity chart, and the 300-500 mb differential vorticity advection to determine

1. Areas of lifting and sinking that support precipitation, convergence-divergence above surface highs and lows, pressure fall and rise centers.
2. Possible instability factors for convection.
3. Which depiction is the best for determining lift? Why?

3. Use the 700 mb analyses to answer the following:

1. Point out sufficient moisture for precipitation and/or convection if available.
2. Point out evidence of instability.
3. Point out evidence of frontogenesis.
   1. What do these areas imply?
4. Point out evidence of lifting or sinking that support precipitation, surface pressure system development, or support for surface rise and fall centers.
5. Do any of these figures raise uncertainty about the use of parcel theory, QG dynamics, etc.?
   1. If so, where are the areas of uncertainty? What analyses would be misleading?
6. What's the relationship between the precipitation and the theta-E analysis?
   1. How does the use of theta-E rather than temperature make interpretation of lift and sufficient moisture easier? How does it make it more difficult?

4. Use the 850 mb analyses to answer the following:

1. Point out sufficient moisture for precipitation and/or convection if available.
2. Point out evidence of instability.
3. Point out evidence of frontogenesis.
   1. What do these areas imply?
4. Point out evidence of lifting or sinking that support precipitation, surface pressure system development, or support for surface rise and fall centers.
5. Do any of these figures raise uncertainty about the use of parcel theory, QG dynamics, etc.?
   1. If so, where are the areas of uncertainty? What analyses would be misleading?
6. What's the relationship between the precipitation and the theta-E analysis?

5. Use the 850-300 mb charts to do the Sutcliffe interpretation of QG processes:

• Areas of advection of thermal vorticity by the mean wind imply lift
• Areas of negative advection of thermal vorticity by the mean wind imply sink.

References:

• College of DuPage 850 mb Theta-E Analyses
• Tom Galarneau's QG Calculations for recent and forecast data
• Ohio State Surface Theta-E Analyses
• SPC Mesoanalysis Page

Send questions to Bob Weisman

Last updated: February 18, 2009 9:27 AM