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Bowen Zhou and Fotini Katopodes Chow

) . Data are sampled at every 3 min between 1730 and 1900 LST. 2) Valley region Lidar scans in Fig. 4 reveal the cross-valley flow induced by the cold-air intrusion on the eastern sidewall. This elevated cross-valley current has a significant impact on turbulent mixing in the valley boundary layer during the evening transition. Figure 11 shows an X – Z slice of θ contours on the 50-m LES grid. The presence of a large-scale wave with a peak at X ~ 0.58 km and trough at X ~ −1.7 km is

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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

1. Introduction Over mountain areas the evolution of the boundary layer is particularly complex as a result of the interaction between boundary layer turbulence and thermally induced mesoscale wind systems, such as the slope and valley winds (e.g., Rotach et al. 2008 ). As the horizontal resolution of operational forecasts progresses to finer resolution, a larger spectrum of thermally induced wind systems can be explicitly resolved. It is therefore useful to document the current state

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

flows were documented by tracking dust plumes at the base of the Sierra Nevada. It was demonstrated that quantitative information about the flows can be extracted using a sequence of scans and Hovmöller-type diagrams. The variety of flows and boundary layer structures visualized by the lidar was not fully explained in the current paper. In future studies, we intend to perform an in-depth investigation of several of the cases presented here using additional analyses and observations from other

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Qingfang Jiang and James D. Doyle

paper presents a case study of an afternoon downslope westerly wind event documented during the intensive observational period (IOP) 12 of SRP, which took place in Owens Valley from 13 to 17 April 2004. The objective of this study is to examine the diurnal variation of flows in Owens Valley, which involves multiscale interactions among the large-scale westerlies, mountain waves, and differential heating within the boundary layer (BL). Over the past few decades, downslope windstorms and large

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

, California. The principal goal of the experiment was to further current understanding and predictability of the dynamics in the mountain-wave rotor–boundary layer (MWRBL) system ( Grubišić et al. 2004 ). Specific goals for the experiment were to understand (i) the role of the upstream flow properties in determining the dynamics and structure of rotors, (ii) wave–rotor dynamic interactions, (iii) internal rotor structure, (iv) rotor–boundary layer interactions, and (v) upper-level gravity breaking and

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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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Qingfang Jiang, Ming Liu, and James D. Doyle

for the first few kilometers and then thicken quickly with the downstream distance, likely due to either hydraulic jump-induced boundary layer (BL) expansion or wave-induced BL separation. A large PM-10 concentration was observed around Owens (dry) Lake at all stations on 25 March ( Fig. 7 ). The observed PM-10 concentration exhibits strong temporal and spatial variations. In general, the PM-10 concentration shows a primary maximum in the afternoon and a secondary maximum before local noon

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Lukas Strauss, Stefano Serafin, and Vanda Grubišić

the lidar in the range of 4–6 km ( Figs. 10f,h ). The middle layer flow(interposed between the low-level current and strong crest-level westerlies and displaying significant shear-driven turbulence at its boundaries) is a typical characteristic of the transition from the initially up-valley ( Figs. 10b,d ) to the fully in-valley westerly regime ( Figs. 11b,d ) in this and other cases. For the case under consideration, that transition concurs with the amplification and expansion of waves above the

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

Gandaki Valley in Nepal ( Egger et al. 2000 ), Zhong and Fast (2003) presented a model intercomparison for flows in the Salt Lake Valley and compared the simulations with measurements from the Vertical Transport and Mixing Experiment (VTMX) campaign ( Doran et al. 2002 ), and De Wekker et al. (2005) used high-resolution simulations to investigate the convective boundary layer structure in the Riviera Valley in Switzerland. Complex nighttime valley flow structures of thermally driven valley flows

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

1. Introduction The structure of turbulence over flat, homogeneous terrain and under various atmospheric boundary layer (ABL) conditions has been investigated extensively (e.g., Wyngaard and Cote 1971 ; Kaimal et al. 1972 , 1976 ; Oncley et al. 1996 ; Albertson et al. 1997 ; Piper and Lundquist 2004 ). These measurements and analyses have led to similarity theories that describe the flow over flat, homogeneous terrain very well. Although the need for the adaptation of the existing theory

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