The role of an upstream cyclone and corresponding synoptic/planetary- scale interactions during the development of a blocking anticyclone. Ph.D. thesis

Results indicate that vorticity advection was the primary forcing mechanism during the block development. Much of the vorticity advection is attributed to the northward advection of negative relative vorticity east of a jet streak that formed between the cyclone and anticyclone. Further, height rises associated with this advection occurred as the ridge downstream from the exploding cyclone became stationary. In fact, the strong northward advection of relative vorticity is primarily due to the advection of synoptic-scale vorticity by the planetary-scale and synoptic-scale winds. This indicates the importance of the proper phasing of the synoptic-scale vorticity with the winds of both scales. Lack of proper phasing between vorticity and wind fields, weaker winds, and weaker flow across the vorticity contours caused the QG model to seriously underestimate the northward amplification of the ridge as the ridge became stationary. -from Author