HYPERBAROCLINIC ZONES: NUMERICAL ANALYSIS AND APPLICATION TO FRONTS.

摘要

An objective-numerical scheme for locating and specifying the intensity of hyperbaroclinic zones (HBZs) is presented and applied in both research and operational environments. The operational model,called DGT*,employs the isobaric gradient of virtual potential temperature (T*) to specify baroclinicity while a directional second derivative of T*is the parameter used to locate the HBZs and indirectly give a measure of their intensity. The DGT*model is diagnosed from an analysis of modeled temperature profiles and a number of real-atmosphere temperature fields at 1000, 850, 700,and 500mb,as taken from winter and summer situations in the years 1964-67. Consideration is given to location,intensity,frequency,slope,and vertical and horizontal distribution and consistency of the HBZs in relation to the numerical processing of data. A key synoptic time, 0000GMT 6March 1966,serves to exemplify analytical and diagnostic features of the HBZs. The numerically-analyzed 1000mb fronts,produced operationally by Fleet Numerical Weather Central,Monterey,California since 1965,are statistically and graphically compared to subjectively-analyzed versions for winter and summer periods up to 30days. The relation of the HBZ to vertical motion and cloud is illustrated by a case study from December 1966. (Author)