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

(1999) showed that for stratified flow impinging on a topographic ridge, low-level jets occur along the northern and southern portions of the ridge flanks, which they refer to as tip jets. In the Northern Hemisphere, westerly flow is deflected primarily leftward around the obstacle, which results in strong jets and downslope flows along the northern flank. Doyle and Shapiro found that jets along the southern ridge flanks can be prominent as well, and consistent with the principal of conservation of

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Vanda Grubišić and Brian J. Billings

for the lofting and transport of aerosols and chemical and biological contaminants ( Raloff 2001 ). This is particularly true over the dry Owens Lake bed located in the lee of the southern Sierra Nevada ( Reid et al. 1993 ). Despite their considerable impact on human activity, and in contrast to the attendant mountain waves, rotors remain relatively poorly understood atmospheric phenomenon. One reason that so little is known about the dynamics of rotors and their internal structure is that they

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Vanda Grubišić and Brian J. Billings

topography upwind, leeside disturbances are almost exclusively generated by the main massif of the Sierra Nevada range. Additionally, the proximity of the Pacific Ocean provides a source of upper-level moisture that commonly gives rise to clouds atop the mountain-wave crests. Conducting a climatology of mountain-wave events in the Sierra Nevada is difficult because of the lack of routine measurements that can be directly and unambiguously related to mountain-wave activity. While mountain waves do have a

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Susanne Drechsel, Georg J. Mayr, Michel Chong, Martin Weissmann, Andreas Dörnbrack, and Ronald Calhoun

km long and embedded between the southern part of the Sierra Nevada to the west and the White–Inyo Mountains to the east ( Fig. 1 ). From the ridgeline with a number of peaks above 4 km MSL, the steep slopes of the Sierra Nevada drop roughly 3000 m to the valley floor, which has a width of 15–30 km. Instruments used for the present study were installed in the vicinity of the town of Independence, California, at the western side of the valley bottom, which was one of the target areas of the T

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

magnitude of the estimated wavelength is comparable to that determined from the aircraft data ( Smith et al. 2008 ). This exercise demonstrates the value of radiosonde-estimated VV in deriving the properties of waves in the stratosphere. The last highlight is the 2D wind structure over Sierra Nevada and Owens Valley observed by the dropsondes along the southern leg during IOP 13 (see Fig. 4 ). A total of 30 dropsondes were deployed along the NCAR GV flight track over the Sierra Nevada and Owens Valley

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James D. Doyle and Dale R. Durran

in section 6 . 2. Numerical model description The atmospheric portion of the Naval Research Laboratory’s Coupled Ocean–Atmospheric Mesoscale Prediction System (COAMPS; Hodur 1997 ) is used to conduct these simulations. A brief overview of the COAMPS model is presented here. The prognostic variables include the Cartesian wind components ( u i , where i = 1, 2, 3), perturbation Exner function ( π ′), and potential temperature ( θ ); the effects of moisture are neglected. The prognostic

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Lukas Strauss, Stefano Serafin, and Vanda Grubišić

programs devoted to the study of mountain waves and rotors were organized in the United States and Europe: the Sierra Wave Project in the southern Sierra Nevada and Owens Valley, California ( Holmboe and Klieforth 1957 ; Grubišić and Lewis 2004 ), a study of lee waves in the French Alps ( Gerbier and Berenger 1961 ), and the Colorado Lee Wave Program in the Rocky Mountains ( Lilly and Toutenhoofd 1969 ). From these field programs and related theoretical studies ( Queney et al. 1960 ), conceptual

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Željko Večenaj, Stephan F. J. De Wekker, and Vanda Grubišić

study. 2. Data This study uses data collected during T-REX, which took place in Owens Valley, California, in March and April of 2006 in an effort to explore the structure and evolution of atmospheric rotors ( Grubišić et al. 2008 ). Owens Valley lies east of the southern Sierra Nevada, which is the tallest, steepest, quasi-two-dimensional topographic barrier in the contiguous United States. Mountain waves and rotors are known to reach particularly striking amplitude and strength there

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Qingfang Jiang, Ming Liu, and James D. Doyle

and causes the sudden thickening of the dust plume by vertically stretching the BL (or causing BL separation from the ground) as suggested by Fig. 6 . 3. Numerical model description a. COAMPS and model setup The atmospheric component of the Coupled Ocean–Atmospheric Mesoscale Prediction System (COAMPS; Hodur 1997 ) is used for this study. COAMPS is a fully compressible, nonhydrostatic, and terrain-following mesoscale model featuring a suite of physical parameterizations. The turbulence kinetic

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Patrick A. Reinecke and Dale Durran

posteriori simulations indicate that simulated waves in high-resolution models were substantially stronger than observed ( Doyle and Jiang 2006 ). Mountain-wave overprediction is not limited to the European Alps. Garvert et al. (2007) used horizontal winds derived from a dual-Doppler radar mounted on the National Oceanic and Atmospheric Administration (NOAA) P-3 aircraft to compare observations of a mountain-wave event over the Oregon Cascades to high-resolution model simulations. They found that the

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