On the importance of mesoscale potential vorticity anomalies and topographic forcing during cyclone redevelopment across the Appalachians: A GALE case study
The evolution of the structure of cyclones and cold fronts over the eastern United States is investigated observationally. Two primary goals of the research are to understand the mechanisms controlling cyclone and frontal evolution across the Appalachian mountains, and to document the presence and importance of mesoscale disturbances during cyclogenesis. First, a climatological survey of seven winter seasons of cyclones and fronts was performed. This study revealed cold fronts are slowed and deformed by the Appalachians, with the cross-frontal pressure and thermal contrasts enhanced considerably across the mountains. In addition, cyclones generally curve northward and dissipate over the mountains while secondary development occurs further south over the lee region. Both upper-level [open quote]forcing[close quote] and low-level thermal structure are important in determining the exact location of redevelopment. Second, a detailed case study was conducted of a cyclone observed during the Genesis of Atlantic Lows Experiment (GALE). The primary cyclone dissipitated over the Northern Appalachians while a secondary lower tropospheric (800-900 mb) cyclone formed over eastern North Carolina. However, strong low-level static stability prevented this disturbance from penetrating to the surface. Instead, cyclogenesis occurred offshore when two mesoscale mid-tropospheric (500 mb) PV maxima, one of which represented an upper level frontal zone, moved over a series of quasi-stationary shallow cloud clusters over the Gulf Stream. Meanwhile, the primary surface cold front was blocked west of the Appalachians, but the mid-level (700-850 mb) front progressed unimpeded across the mountains. Later, a new surface front formed east of the mountains through diabetic processes. These results indicate that future mesoscale models will need to incorporate topography and diabatic processes with increased accuracy.
- Research Organization:
- State Univ. of New York, Albany, NY (United States)
- OSTI ID:
- 7164177
- Country of Publication:
- United States
- Language:
- English
Similar Records
A three-dimensional numerical investigation of a Carolina coastal low-level jet during GALE IOP 2
Interaction between low-level jet and sea surface temperature gradient in the Carolina Capes