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Ronald B. Smith, Bryan K. Woods, Jorgen Jensen, William A. Cooper, James D. Doyle, Qingfang Jiang, and Vanda Grubišić

, Ya D. , and W. R. Peltier , 2001 : Numerical simulations of internal gravity wave breaking in the middle atmosphere: The influence of dispersion and three-dimensionalization. J. Atmos. Sci. , 58 , 132 – 153 . Aris , R. , 1962 : Vectors, Tensors, and the Basic Equations of Fluid Dynamics . Prentice Hall, 286 pp . Bacmeister , J. T. , and M. R. Schoeberl , 1989 : Breakdown of vertically propagating two-dimensional gravity waves forced by orography. J. Atmos. Sci. , 46 , 2109

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Yanping Li, Ronald B. Smith, and Vanda Grubišić

account for the strong valley signal. First, the valley atmosphere is isolated from the free atmosphere by mountain massifs that are acting as walls ( Vergeiner and Dreiseitl 1987 ). Sensible heat warms the valley atmosphere without pressure adjustment resulting from gravity wave generation ( Banta 1984 ; Mohr 2004 ; Canavero and Einaudi 1987 ). Second, the heating of the upper slopes causes large temperature increases in the middle of the valley. Because the pressure variation at the valley floor

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Qingfang Jiang and James D. Doyle

, the ratio of Ŵ ( z = 7.5 km) values from DRY5 and CTRL5 is 1.6 (i.e., given the same perturbation source, the wave amplitude in the dry atmosphere could be more than 50% larger than in the corresponding moist atmosphere). Presumably, the relatively deep moist layer in the lower to middle atmosphere during IOP-5 significantly weakens the waves, likely through reduction of the buoyancy force. For IOP-6c, Ŵ ( z ) derived from DRY6c is larger than that from the corresponding control simulation as

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Bryan K. Woods and Ronald B. Smith

: Propagation from the tropopause to the mesopause and effects on the middle atmosphere. J. Geophys. Res. , 101 , 1571 – 1588 . Alexander , M. J. , and C. Barnet , 2007 : Using satellite observations to constrain parameterizations of gravity wave effects for global models. J. Atmos. Sci. , 64 , 1652 – 1665 . Alexander , M. J. , S. D. Eckermann , D. Broutman , and J. Ma , 2009 : Momentum flux estimates for South Georgia Island mountain waves in the stratosphere observed via

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Thomas Raab and Georg Mayr

of the atmosphere both upstream and downstream of the Sierra Nevada. Analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) global model are used instead of directly comparing observations from, for example, radiosoundings. This method is more consistent, because suitable measurements were not available for all days, or not at representative locations. One drawback of this approach is that the model topography is much smoother and Owens Valley is not resolved (cf. Fig. 3

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Lukas Strauss, Stefano Serafin, and Vanda Grubišić

characteristics of the upstream profiles (colored in blue) include low wind speed and wind direction considerably deviating from the cross-mountain direction (~255°) below ridge height (indicative of upstream blocking), increased stability at and above crest level, and weaker stability and rapid increase in wind speed in the free atmosphere. Such a vertically layered atmosphere corresponds to a Scorer parameter [defined as , where N and U are the upstream stability and cross-mountain wind speed

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C. David Whiteman, Sebastian W. Hoch, and Gregory S. Poulos

secondary selection criterion was used to ensure that the measured temperatures at the elevations chosen were representative of the bulk valley atmosphere rather than local microclimates on the slope. Where possible, HOBOs were placed on convex terrain (i.e., on ridges rather than gullies or other declivities) away from bushes and rock outcrops. The upper segments of the Manzanar and west lines were on ridges, while the lower segments were on a broad and rather uniform alluvial slope. The lower segment

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Qingfang Jiang, James D. Doyle, Vanda Grubišić, and Ronald B. Smith

1. Introduction Turbulence is ubiquitous in high Reynolds fluids such as the earth’s atmosphere. Atmospheric turbulence has been the subject of numerous studies, mostly based on field observations or wind tunnel experiments. However, compared to boundary layer turbulence, detailed documentation of atmospheric turbulence in mountainous areas is still relatively rare. Complexity over mountains is enhanced in part because turbulence can be generated by mountain waves at levels well above the

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Peter Sheridan and Simon Vosper

than that in the valley (typically because of daytime solar warming within the valley) and, flowing over the Sierra Nevada, induces downslope winds by undercutting the valley atmosphere. Jiang and Doyle (2008) , in a study of diurnal variation of downslope winds in Owens Valley, demonstrated this effect for the case of only moderate mountaintop winds by using observations and high-resolution modeling, terming the flow “in-valley westerly.” Mayr and Armi (2010) show further evidence from T

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James D. Doyle, Saša Gaberšek, Qingfang Jiang, Ligia Bernardet, John M. Brown, Andreas Dörnbrack, Elmar Filaus, Vanda Grubišić, Daniel J. Kirshbaum, Oswald Knoth, Steven Koch, Juerg Schmidli, Ivana Stiperski, Simon Vosper, and Shiyuan Zhong

Schoeberl 1989 ). Mountain waves can have an important impact on the atmosphere because of their role in downslope windstorms ( Klemp and Lilly 1975 ); clear-air turbulence ( Clark et al. 2000 ); vertical mixing of water vapor, aerosols, and chemical constituents in the stratosphere ( Dörnbrack and Dürbeck 1998 ); potential vorticity generation ( Schär and Durran 1997 ); and orographic drag influence on the general circulation ( Bretherton 1969 ; Ólafsson and Bougeault 1996 ). Although numerical models

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