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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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Juerg Schmidli, Gregory S. Poulos, Megan H. Daniels, and Fotini K. Chow

1. Introduction Understanding the winds within a valley and their interactions with the larger-scale forcings is of interest for a number of reasons. For example, the dispersion of pollutants in a valley depends strongly on local valley circulations (e.g., Whiteman 1989 ; Fast et al. 2006 ); nocturnal minimum surface temperatures depend strongly on the near-surface wind speed (e.g., Estournel and Guedalia 1985 ; Steeneveld et al. 2006 ) and hence on the strength of the valley wind; land

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Laurence Armi and Georg J. Mayr

conditions. The locations of measurements used here are shown in Fig. 1 . A radiosounding at LeMoore, California, (marked with a “U” in the top panel) measured vertical profiles of the upstream conditions, and a radiosounding at Independence (California) Airport (shown with a “D” in both panels) provided downstream data. In situ and cloud radar data from the University of Wyoming King Air aircraft ( Kelly et al. 1992 ; Damiani and Haimov 2006 ) fill the gap between the radiosoundings. The aircraft flew

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Thomas Raab and Georg Mayr

period (no-IOP): Weak dynamic and hydrostatic forcing This day showed the evolution of the thermally driven valley and slope wind system in Owens Valley despite a weak southwesterly flow across the region and a slightly colder air mass (Δ θ υ = −0.3 K) west of the sierra (cf. Fig. 4a ). No gravity wave structures were visible in the cirrus clouds, which appeared at midafternoon and covered most of the sky by the end of the day. 1) Observations The diurnal evolution of θ υ computed from Eq. (1

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Lukas Strauss, Stefano Serafin, and Vanda Grubišić

1. Introduction Atmospheric gravity waves excited in stably stratified flow over a mountain ridge are often accompanied by significant low-level turbulence downwind of the ridge. The great impact mountain waves can have on the lee-side flow was first evidenced by observations of stationary cloud formations, for instance, in the lee of the Dinaric Alps along the Adriatic coast of Croatia ( Mohorovičić 1889 ; Grubišić and Orlić 2007 ) or over the Sudetes in central Europe ( Koschmieder 1920

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Qingfang Jiang and James D. Doyle

includes numerical studies using mesoscale models with explicit cloud parameterizations. The impact of moisture on trapped waves has been examined by Durran and Klemp (1982a) using a nonlinear numerical model with simple cloud physics. They demonstrated that moist processes in general weaken, and sometimes even disrupt trapped waves. Durran and Klemp (1983) studied the sensitivity of two-dimensional hydrostatic mountain waves to moist effects and concluded that moist processes tend to weaken

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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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Michael Hill, Ron Calhoun, H. J. S. Fernando, Andreas Wieser, Andreas Dörnbrack, Martin Weissmann, Georg Mayr, and Robert Newsom

cloud mass near Bakar Bay, Croatia, that was likely a result of a large circulating wind ( Grubišić and Orlić 2007 ). Observational evidence of these flows has been plentiful, including, for example, the movement of dust plumes lofted by strong winds, encounters of severe turbulence from aircraft, ground-based atmospheric measurements, and rotor or mountain-wave clouds visible from both the ground and from space. Recently, numerical simulation has revealed detailed vortical motions embedded in

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Juerg Schmidli, Brian Billings, Fotini K. Chow, Stephan F. J. de Wekker, James Doyle, Vanda Grubišić, Teddy Holt, Qiangfang Jiang, Katherine A. Lundquist, Peter Sheridan, Simon Vosper, C. David Whiteman, Andrzej A. Wyszogrodzki, and Günther Zängl

between the minimum and maximum vertical grid spacing was given by where Δ z min = 20 m, Δ z m = 110 m, a = (1 + n )/2, α = 0.5, and n = 20. The lateral boundary conditions are periodic. A Rayleigh sponge layer, starting at 5 km, was specified as the top boundary condition. All simulations were run with the Coriolis force turned off. The models were integrated for 12 h from sunrise at 0600 local time (LT) to sunset at 1800 LT. The temporal evolution of surface sensible heat flux is determined

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Vanda Grubišić and Brian J. Billings

dynamics were made during this project. The strongest wave events were correlated with strong winds at the mountain crest level, a pronounced inversion layer between 3600 and 5800 m (approximately at or 2 km above mountain crest level), and large vertical shear in the lower troposphere. Atmospheric rotors and associated roll (rotor) clouds were classified into two types. A typical roll cloud, associated with a lee-wave rotor, was found to be located under the crest of a lee wave, paralleling the

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