Comparison of Diagnostic and Kinematic Vertical Motion Fields Associated withCurved and Straight Jet Streak Adjustment Processes

摘要

Investigative research was performed on real and simulated jet streaks todetermine the relationship of the diagnostic Rossby number with kinematic, balanced and non-balanced omega fields as a function of magnitude, wind shear and curvature. Hydrodynamic instability was also examined as influencing omega values. A two-layer primitive equation model was used to produce forty five jet streak cases. Seven cases were quasi-barotropic with upper winds equal to the lower level winds. Twenty four were equivalent barotropic with the upper level winds set to equal three times the magnitude of the lower level winds. Four cases were run with a beta plane versus a constant f plane. The remaining ten cases were simulated baroclinic conditions. One cyclonic jet streak using operational data also examined. Model results indicated a consistent weakening for both the 800 mb and 400 mb wind maximums for all jet streak cases when the upper and lower-level waves were in phase and of the same speed. When the upper level was set to equal 3 times the magnitude of the lower jet while maintaining the upper and lower level waves in phase resulted in a larger wind decrease while the 800 mb level showed an increase over the 24 hours of the run in each jet streak case. For the beta and easterly jet streak cases the upper level decrease was somewhat less. The baroclinic cases showed a very slight decrease of increase over the 24 hours of the run. Keywords: Thesis. (jhd)