Rotor and subrotor dynamics in the lee of three-dimensional terrain

被引:69
作者
Doyle, James D.
Durran, Dale R.
机构
[1] Naval Res Lab, Marine Meteorol Div, Monterey, CA 93943 USA
[2] Univ Washington, Seattle, WA 98195 USA
关键词
D O I
10.1175/2007JAS2352.1
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
The internal structure and dynamics of rotors that form in the lee of topographic ridges are explored using a series of high-resolution eddy-resolving numerical simulations. Surface friction generates a sheet of horizontal vorticity along the lee slope that is lifted aloft by the mountain lee wave at the boundary layer separation point. Parallel-shear instability breaks this vortex sheet into small intense vortices or subrotors. The strength and evolution of the subrotors and the internal structure of the main large-scale rotor are substantially different in 2D and 3D simulations. In 2D, the subrotors are less intense and are ultimately entrained into the larger-scale rotor circulation, where they dissipate and contribute their vorticity toward the maintenance of the main rotor. In 3D, even for flow over a uniform infinitely long barrier, the subrotors are more intense, and primarily are simply swept downstream past the main rotor along the interface between that rotor and the surrounding lee wave. The average vorticity within the interior of the main rotor is much weaker and the flow is more chaotic. When an isolated peak is added to a 3D ridge, systematic along-ridge velocity perturbations create regions of preferential vortex stretching at the leading edge of the rotor. Subrotors passing through such regions are intensified by stretching and may develop values of the ridge-parallel vorticity component well in excess of those in the parent, shear-generated vortex sheet. Because of their intensity, such subrotor circulations likely pose the greatest hazard to aviation.
引用
收藏
页码:4202 / 4221
页数:20
相关论文
共 79 条
[1]  
Afanasyev YD, 1998, J ATMOS SCI, V55, P19, DOI 10.1175/1520-0469(1998)055<0019:TTDOSF>2.0.CO
[2]  
2
[3]  
BANTA RM, 1990, 5 C MOUNT MET BOULD, P68
[4]  
BOUGEAULT P, 1983, MON WEATHER REV, V111, P420, DOI 10.1175/1520-0493(1983)111<0420:ANRUBC>2.0.CO
[5]  
2
[6]  
CARNEY TQ, 1996, AC0057 FED AV ADM AD
[7]  
Clark TL, 2000, J ATMOS SCI, V57, P1105, DOI 10.1175/1520-0469(2000)057<1105:OOADCA>2.0.CO
[8]  
2
[9]   The evolution of lee-wave-rotor activity in the lee of Pike's Peak under the influence of a cold frontal passage: Implications for aircraft safety [J].
Darby, Lisa S. ;
Poulos, Gregory S. .
MONTHLY WEATHER REVIEW, 2006, 134 (10) :2857-2876
[10]  
Dawson P. J., 1982, GEOLOGICAL SOC AM SP, V192, P55