. Assignment 11. Due April 9

Review the information on relative vorticity, planetary vorticity and absolute vorticity in the Djuric text.

Graphics at 300 mb will be analyzed for the 48 h period beginning at 12z March 21. The following uses GARP to evaluate the kinematics of the wind field using the AVN model forecast.

• 1. Overlay 300 mb streamlines and 300 mb isotachs (kts) at 10 m/s intervals. It may be helpful to shade the isotachs at 20 m/s intervals. Use the North America domain.
  • a. Add absolute vorticity at the 300 mb level. Where are the centers of large absolute vorticity at the initial time in relation to the ridges and troughs?
  • b. How did those vorticity centers evolve with time relative to the movement of the ridges and troughs and the intensity of the ridges and troughs? Which ones intensified? Which ones weakened?
• 2. Use the CONUS domain. Overlay isotachs and streamlines at 300 mb.
  • a. Identify at the initial time only, at least 1 area of each of the following: (1) large positive advection of planetary vorticity; (2) large negative advection of planetary advection; (3) large positive advection of relative vorticty; (4) large negative advection of relative vorticity; (5) large positive advection of absolute vorticity; 6) large negative advection of absolute vorticity.
• 3. Where do you expect the vorticity centers that you identified in 1) to move and how do you expect those vorticity maxima to change in magnitude (increase? decrease?)
• 4. Look at model forecast for the next 6 and 12 hours. How well did the vorticity tendencies at the initial time relate to the change in absolute vorticity over the 6-12 hour period? How do you explain the differences or similarities?
• Keep your answers short and focussed. Email responses to me by the due date.