Balanced dynamics of mesoscale vortices produced in simulated convective systems

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1994)051<2005:BDOMVP>2.0.CO;2· OSTI ID:6710099

Davis, C A; Weisman, M L ^[1]

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1. National Center for Atmospheric Research, Boulder, CO (United States)

Long-lived, mesoscale convective systems are known to occasionally produce Mesoscale Convective Vortices (MCVs) in the lower to middle troposphere with horizontal scales averaging 100-200 km. The formation of MCVs is investigated using fully three-dimensional cloud model simulations of idealized, Mesoscale Convective Systems (MCSs), initialized with a finite length line of unstable perturbations. In agreement with observations, the authors find that environmental conditions favoring MCV formation exhibit weak vertical shear confined to roughly the lowest 3 km, provided the Coriolis parameter (f) is chosen appropriate for midlatitudes. With f = 0, counterrotating vortices form on the line ends, positive to the north and negative to the south with westerly environmental shear. The MCV and end vortices are synonymous with anomalies of potential vorticity (PV). Using PV inversion techniques, the authors show that the vortices are nearly balanced, even with f = 0. However, the formation of mesoscale vortices depends upon the unbalanced, sloping, front-to-rear and rear inflow circulations of the mature squall line. End vortices form partly from the tilting of ambient shear but more from the tilting of the perturbation horizontal vorticity inherent in the squall line circulation. With the addition of earth's rotation, an asymmetric structure results with the cyclonic vortex dominant on the northern end of the line.

• OSTI ID: 6710099
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 51:14; ISSN 0022-4928; ISSN JAHSAK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
540120 -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (1990-)
ATMOSPHERIC CIRCULATION
COMPUTERIZED SIMULATION
CONVECTION
DISASTERS
EARTH ATMOSPHERE
ENERGY TRANSFER
HEAT TRANSFER
HURRICANES
MASS TRANSFER
NATURAL CONVECTION
SIMULATION
STORMS
VORTICES