Nonzonal Gravity Wave Breaking in the Winter Mesosphere

1984 ◽  
pp. 45-64 ◽  
Author(s):  
Mark R. Schoeberl ◽  
Darrell F. Strobel
Keyword(s):  
Gravity Wave ◽  
Wave Breaking

The Interaction of Katabatic Flow and Mountain Waves. Part II: Case Study Analysis and Conceptual Model

2007 ◽  
Vol 64 (6) ◽  
pp. 1857-1879 ◽  
Author(s):  
Gregory S. Poulos ◽  
James E. Bossert ◽  
Thomas B. McKee ◽  
Roger A. Pielke
Keyword(s):  
Conceptual Model ◽  
Gravity Wave ◽  
Wave Breaking ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Wave System ◽  
Katabatic Flow ◽  
Mountain Wave ◽  
Mountain Waves ◽  
Wave Evolution

Via numerical analysis of detailed simulations of an early September 1993 case night, the authors develop a conceptual model of the interaction of katabatic flow in the nocturnal boundary layer with mountain waves (MKI). A companion paper (Part I) describes the synoptic and mesoscale observations of the case night from the Atmospheric Studies in Complex Terrain (ASCOT) experiment and idealized numerical simulations that manifest components of the conceptual model of MKI presented herein. The reader is also referred to Part I for detailed scientific background and motivation. The interaction of these phenomena is complicated and nonlinear since the amplitude, wavelength, and vertical structure of the mountain-wave system developed by flow over the barrier owes some portion of its morphology to the evolving atmospheric stability in which the drainage flows develop. Simultaneously, katabatic flows are impacted by the topographically induced gravity wave evolution, which may include significantly changing wavelength, amplitude, flow magnitude, and wave breaking behavior. In addition to effects caused by turbulence (including scouring), perturbations to the leeside gravity wave structure at altitudes physically distant from the surface-based katabatic flow layer can be reflected in the katabatic flow by transmission through the atmospheric column. The simulations show that the evolution of atmospheric structure aloft can create local variability in the surface pressure gradient force governing katabatic flow. Variability is found to occur on two scales, on the meso-β due to evolution of the mountain-wave system on the order of one hour, and on the microscale due to rapid wave evolution (short wavelength) and wave breaking–induced fluctuations. It is proposed that the MKI mechanism explains a portion of the variability in observational records of katabatic flow.

scholarly journals Evidence of gravity wave breaking in lidar data from the mesopause region

2003 ◽  
Vol 30 (4) ◽  
Author(s):  
Patricia Minthorn Franke ◽  
Richard L. Collins
Keyword(s):  
Gravity Wave ◽  
Wave Breaking ◽  
Lidar Data ◽  
Mesopause Region

scholarly journals Numerical simulation of gravity wave breaking in the lower thermosphere

2012 ◽  
Vol 117 (D21) ◽  
pp. n/a-n/a ◽  
Author(s):  
Thomas S. Lund ◽  
David C. Fritts
Keyword(s):  
Numerical Simulation ◽  
Gravity Wave ◽  
Wave Breaking ◽  
Lower Thermosphere

scholarly journals Local mean state changes due to gravity wave breaking modulated by the diurnal tide

2000 ◽  
Vol 105 (D10) ◽  
pp. 12381-12396 ◽  
Author(s):  
Han-Li Liu ◽  
Maura E. Hagan ◽  
Raymond G. Roble
Keyword(s):  
Gravity Wave ◽  
Wave Breaking ◽  
Diurnal Tide ◽  
Local Mean ◽  
State Changes ◽  
Mean State

Some Influences of Background Flow Conditions on the Generation of Turbulence due to Gravity Wave Breaking above Deep Convection

2008 ◽  
Vol 47 (11) ◽  
pp. 2777-2796 ◽  
Author(s):  
Todd P. Lane ◽  
Robert D. Sharman
Keyword(s):  
Gravity Wave ◽  
Wave Breaking ◽  
Wind Shear ◽  
Critical Level ◽  
Safety Issue ◽  
Deep Convection ◽  
Aviation Industry ◽  
Moist Convection ◽  
Flow Conditions ◽  
Background Flow

Abstract Deep moist convection generates turbulence in the clear air above and around developing clouds, penetrating convective updrafts and mature thunderstorms. This turbulence can be due to shearing instabilities caused by strong flow deformations near the cloud top, and also to breaking gravity waves generated by cloud–environment interactions. Turbulence above and around deep convection is an important safety issue for aviation, and improved understanding of the conditions that lead to out-of-cloud turbulence formation may result in better turbulence avoidance guidelines or forecasting capabilities. In this study, a series of high-resolution two- and three-dimensional model simulations of a severe thunderstorm are conducted to examine the sensitivity of above-cloud turbulence to a variety of background flow conditions—in particular, the above-cloud wind shear and static stability. Shortly after the initial convective overshoot, the above-cloud turbulence and mixing are caused by local instabilities in the vicinity of the cloud interfacial boundary. At later times, when the convection is more mature, gravity wave breaking farther aloft dominates the turbulence generation. This wave breaking is caused by critical-level interactions, where the height of the critical level is controlled by the above-cloud wind shear. The strength of the above-cloud wind shear has a strong influence on the occurrence and intensity of above-cloud turbulence, with intermediate shears generating more extensive regions of turbulence, and strong shear conditions producing the most intense turbulence. Also, more stable above-cloud environments are less prone to turbulence than less stable situations. Among other things, these results highlight deficiencies in current turbulence avoidance guidelines in use by the aviation industry.

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