Kinematics of the Wind Field. Assignment 9. Due April 11
Purpose: (1) to analyze the kinematics of the wind field as diagnosed manually and by an operational model.
(2) examine the
evolution of the jet stream over a 48 h period.
Review the information on kinematics in
the Djuric text.
Graphics at 300 mb will be analyzed for the 48 h period beginning at 00z 20 February.
1. Perform a manual isotach analysis at 5 m/s intervals of the 300 mb wind field at 00z 21 February. Label neatly any jet axes.
2. Perform a manual streamline analysis of the 300 mb wind field at 00z 21 February.
3. The following uses GARP to evaluate the kinematics of the wind field using the Eta model forecast used in the previous assignment.
- How did the jets move during this period?
- How did the structure of the low over the western U.S. change during this period as defined by the streamlines of the wind?
- How does the geostrophic wind compare to the actual wind over time? Use mag(geo)
How do you explain any differences?
- How did the relative vorticity field change during the period?
- Identify at the initial time areas of strong cyclonic speed shear and curvature.
- How does the relative vorticity computed from the geostrophic wind
compare to that from the total wind field? How do you explain any differences?
- How did the divergence field evolve with time?
- Identify at the initial time areas of stretching and diffluence.
- How do areas of maximum divergence or convergence relate to areas of maxima or minima in relative vorticity?
Keep your answers short and focussed. Email responses to me and turn in your manual analyses by the due date.