The Ohio Valley Wave-Merger Cyclogenesis Event of 25–26 January 1978. Part II: Diagnosis Using Quasigeostrophic Potential Vorticity Inversion

作者：Gregory J. Hakim, Daniel Keyser, Lance F. Bosart · 发表于：Monthly Weather Review · 年份：1996 · DOI：10.1175/1520-0493(1996)124<2176:tovwmc>2.0.co;2 · 被引用次数：113 · 研究领域：Oceanographic and Atmospheric Processes、Climate variability and models、Tropical and Extratropical Cyclones Research

The dynamical interactions between precursor disturbances during the wave-merger cyclogenesis event of 25–26 January 1978 over eastern North America are diagnosed using quasigeostrophic potential vorticity (QGPV) inversion. This case is characterized by two prominent preexisting upper-level disturbances that induce rapid surface cyclogenesis as they come into close proximity. Static QGPV inversion is used to attribute a particular geopotential height field to the QGPV associated with each precursor disturbance. The full flow is partitioned into the following components: the northern upper precursor, the southern upper precursor, and the background flow. Prognostic QGPV inversion is used to quantify the instantaneous geopotential height tendencies attributable to each of these flow components. The static-inversion results for the upper precursors exhibit the structure of baroclinic vortices with maximum amplitude near the tropopause. During the 48-h period spanning the period of study of this event, these vortices rotate cyclonically about a point between them with the rate of rotation increasing as the vortices draw closer together. The background flow appears as a synoptic-scale trough, with the meridional tilt of the trough axis positive (negative) prior to (during) rapid surface cyclogenesis. Prior to surface cyclogenesis, the background flow is also confluent in the vicinity of the vortices, acting to bring them closer together. Rapid surface cyclogenesis occurs as the vo...