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Qingfang Jiang and James D. Doyle

1. Introduction Moist processes have been largely ignored in the majority of mountain-wave studies, partially because of the complexity associated with moisture and microphysical processes. Studies of the interaction between moist airflow and mesoscale topography can be broadly classified into two categories. The first category includes quasi-analytical studies with highly simplified representations of moist processes. For example, a set of two-dimensional steady-state linear wave solutions

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Ivana Stiperski and Vanda Grubišić

instability of steady mountain waves . J. Fluid Mech. , 568 , 303 – 327 . Louis , J. F. , 1979 : A parametric model of vertical eddy fluxes in the atmosphere . Bound.-Layer Meteor. , 17 , 187 – 202 . Louis , J. F. , M. Tiedtke , and J. F. Geleyn , 1982 : A short history of the operational PBL parameterization at ECMWF . Proc. Workshop on Planetary Boundary Layer Parameterization, Reading, United Kingdom, European Centre for Medium-Range Weather Forecasts, 59–79 . Mayr , G. J. , and A

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

1. Introduction The Sierra Nevada is a north-northwest–south-southeast-oriented mountain range of approximately 650-km length, 100-km width, and features the tallest peak, Mt. Whitney (4417 m), and the steepest orographic gradient along the eastern slope in the contiguous United States ( Fig. 1 ). The Sierra Nevada is well known for generating large-amplitude mountain waves (i.e., the Sierra Wave). Although topographic ridges such as the Sierra Nevada are often considered a quasi

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Junhong Wang, Jianchun Bian, William O. Brown, Harold Cole, Vanda Grubišić, and Kate Young

1. Introduction The vertical motion of the atmosphere represents atmospheric dynamics ranging from small-scale turbulence in the planetary boundary layer (PBL) and inside clouds to various types of waves and the large-scale ascending and descending parts of meridional circulations. The measurement of vertical velocity (VV) in PBL is important for calculating air–surface transport of mass and energy. Vertical motion inside clouds affects cloud formation (e.g., Paluch and Lenschow 1991 ) and the

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James D. Doyle and Dale R. Durran

: Lower turbulent zones associated with mountain lee waves. J. Appl. Meteor. , 13 , 54 – 61 . Lilly , D. K. , 1962 : On the numerical simulation of buoyant convection. Tellus , 14 , 148 – 172 . Louis , J. F. , 1979 : A parametric model of vertical eddy fluxes in the atmosphere. Bound.-Layer Meteor. , 17 , 187 – 202 . Louis , J. F. , M. Tiedtke , and J. F. Geleyn , 1982 : A short history of the operational PBL-parameterization at ECMWF. Proc. Workshop on Planetary Boundary

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Qingfang Jiang and James D. Doyle

–79 . Mellor , G. L. , and T. Yamada , 1974 : A hierarchy of turbulence closure models for planetary boundary layers. J. Atmos. Sci. , 31 , 1791 – 1806 . Ólafsson , H. , and P. Bougeault , 1997 : The effect of rotation and surface friction on orographic drag. J. Atmos. Sci. , 54 , 193 – 210 . Peltier , W. R. , and T. L. Clark , 1979 : The evolution and stability of finite amplitude mountain waves. Part II: Surface wave drag and severe downslope winds. J. Atmos. Sci. , 36

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Stephan F. J. De Wekker and Shane D. Mayor

. , 64 , 401 – 420 . Lighthill , M. J. , 1967 : Waves in fluids. Commun. Pure Appl. Math. , 20 , 267 – 293 . Lin , C-L. , J. C. McWilliams , C-H. Moeng , and P. P. Sullivan , 1996 : Coherent structures in a neutrally stratified planetary boundary layer. Phys. Fluids , 8 , 2626 – 2639 . Mayor , S. D. , and E. W. Eloranta , 2001 : Two-dimensional vector wind fields from volume imaging lidar data. J. Appl. Meteor. , 40 , 1331 – 1346 . Mayor , S. D. , and S. M

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Qingfang Jiang, Ming Liu, and James D. Doyle

until the westerlies penetrate into the valley in the afternoon. This study is partially motivated by observations obtained from the Terrain-induced Rotor Experiment (T-REX; Grubišić et al. 2008 ), which took place over the Sierra Nevada and Owens Valley during March–April 2006. The primary focus of T-REX is on mountain waves and wave-induced rotor circulations associated with the cross-barrier flow impinging on the sierra ridge. As will be shown below, the observed PM-10 concentration around Owens

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James D. Doyle, Vanda Grubišić, William O. J. Brown, Stephan F. J. De Wekker, Andreas Dörnbrack, Qingfang Jiang, Shane D. Mayor, and Martin Weissmann

results from very high-resolution numerical simulations presented in Doyle and Durran (2007) reveal the presence of turbulent, small-scale vortices that they refer to as subrotors , which may pose a significant aviation hazard because of their intensity. However, the existence of subrotor vortices has never been observationally confirmed as sufficient quantitative measurements to document even the basic characteristics of subrotors have been lacking. The Sierra Wave Project and its follow-on, the

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Bowen Zhou and Fotini Katopodes Chow

, when warming associated with wave troughs (downward-curving potential temperature isentropes) vanishes immediately after the wave passes. The latter usually occur on a much shorter time scale ~ O (1 min). Intermittent turbulence has been observed during field experiments since the last decade, yet its origin is not well understood. A few known mechanisms include passing density currents ( Sun et al. 2002 ), breaking shear-instability waves ( Newsom and Banta 2003 ), solitary waves and downward

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