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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

and turbulence, and (iii) the uncertainties associated with the parameterization of radiation transfer and surface–atmosphere interactions. Thus apart from an idealized topography, the setup of the simulations is as close as possible to real-case simulations. The models are run with comprehensive model physics including a radiation transfer scheme, land surface scheme, and turbulence parameterization. A large computational domain and periodic lateral boundary conditions are used in order to

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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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Yanping Li, Ronald B. Smith, and Vanda Grubišić

1. Introduction Diurnal solar atmospheric tides are excited primarily by the absorption of solar radiation by water vapor in the troposphere and ozone in the stratosphere, as well as by the turbulent heat transfer near the ground ( Forbes and Garrett 1979 ). Tides can be easily detected in surface pressure observations. In a hydrostatic atmosphere, surface pressure variations result from the integral effect in the vertical direction of density and temperature perturbations above the ground. For

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

. Atmos. Oceanic Technol. , 12 , 985 – 995 . Moeng , C-H. , 1984 : A large-eddy simulation model for the study of planetary boundary-layer turbulence. J. Atmos. Sci. , 41 , 2052 – 2062 . Monin , A. S. , and A. M. Obukhov , 1954 : Basic laws of turbulent mixing in the ground layer of the atmosphere. Akad. Nauk SSSR Geofiz. Inst. Tr. , 151 , 163 – 187 . Morse , C. S. , R. K. Goodrick , and L. B. Cornman , 2002 : The NIMA method for improved moment estimation from Doppler

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

temporal and spatial scales. Second, flow over complex terrain can pose a hazard to aircraft. Third, complex terrain is also capable of inducing circulations that vent particulate matter and trace gasses into midtroposphere altitudes and the free atmosphere ( Henne et al. 2004 ). As a result, complex terrain flows may have a significant role in air quality and potentially in climate change studies. Great technological advancements have occurred in the past 40 years with laser remote sensing that have

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Qingfang Jiang and James D. Doyle

–4 km MSL) for IOP-6c and -8 ( Table 2 ). 3. Model description The atmospheric component of the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS, 1 Hodur 1997 ) is used for this study. COAMPS is a nonlinear, compressible, nonhydrostatic terrain-following mesoscale model with a suite of physical parameterizations. The turbulent mixing and diffusion are represented using a prognostic equation for the turbulence kinetic energy (TKE) budget ( Mellor and Yamada 1974 ). The surface heat and

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Bowen Zhou and Fotini Katopodes Chow

transient warming episode at the valley floor. The model also uncovers a new terrain-induced mechanism responsible for upside-down turbulent mixing. The elevated source of turbulence is an intruding cold-air drainage current into the stratified valley atmosphere. The numerical approach used in this study is large-eddy simulation (LES). To conduct LES of realistic SBL flow over complex terrain, a grid-nesting approach is adopted. Grid nesting takes information from the coarse grid and passes it to the

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

) with thermally driven upvalley and upslope flows ( Fig. 2a ). A transition from a quiescent valley atmosphere to a valley atmosphere affected by mountain-wave activity occurred during midafternoon between 2300 and 0000 UTC ( Fig. 2b ). While southeasterly flow prevailed in the valley center the flow on the western slope became more irregular with downslope winds replacing the upslope winds and colliding with the upvalley flow ( Fig. 2c ). Southeasterly winds up to 15 m s −1 in a layer between 400

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

observed and idealized flows in this study are performed using the atmospheric module of the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS; Hodur 1997 ). The COAMPS model is based on a finite-difference approximation to the fully compressible, nonhydrostatic equations and uses a terrain-following vertical coordinate transformation. In the real data forecasts, the finite-difference schemes are of second-order accuracy in time and space, while the idealized simulations use a fourth

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Qingfang Jiang and James D. Doyle

aspects of the flow of stratified fluids: I. A theoretical investigation. Tellus , 5 , 42 – 57 . 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

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