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Bryan K. Woods and Ronald B. Smith

temperature and pressure instruments, and 3) aircraft with a gust probe and inertial platform. The mathematical analysis of aircraft data has advanced also, from using potential temperature to chart streamline deflection to using longitudinal and vertical velocity to compute momentum flux and Fourier cross-spectra to determine dominant wave scales and phase relationships. This history probably begins with Kuettner’s study of stationary updrafts and downdrafts in mountain waves using a sailplane variometer

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Ronald B. Smith, Bryan K. Woods, Jorgen Jensen, William A. Cooper, James D. Doyle, Qingfang Jiang, and Vanda Grubišić

properties of the tropopause may influence mountain waves propagating into the stratosphere. The sharp lapse rate and wind shear change at the tropopause may cause partial reflection and discontinuous aspects of wave structure. According to linear theory, the only wave properties that are likely to be continuous across the tropopause are the momentum flux (MF) and possibly the energy flux (EF; Eliassen and Palm 1961 , hereafter EP61 ). Once the waves have entered the stratosphere, the greater static

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

storage of TKE, which is equal to the increase or decrease of TKE in time at a given location due to all of the TKE production and destruction terms. These terms include advection of TKE from the layers above or below by the mean vertical wind (term II); the buoyant production/consumption (term III), which depends on the sign of the heat flux ; the mechanical (shear) production (term IV), which is typically positive in the boundary layer because of opposite signs of the horizontal momentum fluxes and

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James D. Doyle, Saša Gaberšek, Qingfang Jiang, Ligia Bernardet, John M. Brown, Andreas Dörnbrack, Elmar Filaus, Vanda Grubišić, Daniel J. Kirshbaum, Oswald Knoth, Steven Koch, Juerg Schmidli, Ivana Stiperski, Simon Vosper, and Shiyuan Zhong

the perturbation velocity rather than the mean fields in the no-slip simulations, hence the basic-state flow is assumed to be in geostrophic balance. The surface heat flux is zero in all models, implying that the ground temperature is in balance with the surface air temperature. No moist processes are included in any of the simulations. Vertical mixing in the free atmosphere is the only physical parameterization included within the models for the free-slip simulations. For the no-slip simulations

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C. David Whiteman, Sebastian W. Hoch, and Gregory S. Poulos

of the Manzanar line was placed alongside a gravel road in a broad and shallow declivity. b. The embedded tall towers Three (central, west, and south) heavily instrumented integrated surface flux facility (ISFF) towers, installed and operated by the National Center for Atmospheric Research (NCAR), provided supplementary meteorological data. These 34-m towers ( Fig. 1 ) were located inside the network of temperature dataloggers. The central and south sites were on the valley floor on slopes of

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Qingfang Jiang and James D. Doyle

+ υ ′ 2 + w ′ 2 )/2 is the turbulence kinetic energy per unit mass; ( U , V ) and ( u ′, υ ′, w ′) denote grid-scale horizontal wind vectors and ensemble turbulent wind fluctuations, respectively; β is the thermal expansion coefficient; S e = 0.5 and Γ = 0.17 are constants; l m is the mixing length formulated based on Mellor and Yamada (1974) and Thompson and Burk (1991) ; and D e represents the subgrid-scale TKE mixing. The subgrid-scale mixing of momentum and heat fluxes is

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

surface–atmosphere exchanges over mountainous regions are closely linked to slope and valley flows; and the effects of these flows on mesoscale fluxes need to be parameterized in numerical weather prediction and climate models (e.g., Noppel and Fiedler 2002 ; Weigel et al. 2007 ; Rotach and Zardi 2007 ). Three major mechanisms that can produce within-valley winds are thermal forcing, pressure-driven channeling, and downward momentum transport ( Whiteman and Doran 1993 ). Thermal forcing refers to

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

the transect means, (i.e., U , V , and θ ) to obtain the vertical derivatives of those variables ( Fig. 4 ). In addition, the flux Richardson number Ri f = b / s , where b = ( g / θ ) θ ″ w ″ is the buoyancy production rate of turbulent kinetic energy (TKE) and s = u ″ w ″ (∂ U /∂ z ) + υ ″ w ″ (∂ V /∂ z ) is the shear production rate, estimated from all flight legs is included in Fig. 4 as well. The double-primed variables denote perturbations associated with large eddies and

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Qingfang Jiang, Ming Liu, and James D. Doyle

and in-valley circulations below the mountaintop level ( Fig. 5b ). Upstream of the sierras, the lower to midtroposphere is relatively stable during IOP 6. Inside the valley, the early morning sounding reveals a shallow stable layer above the valley floor, and in the afternoon, a deep well-mixed layer develops in association with strong surface heat fluxes within Owens Valley (not shown). During the afternoon of 25 March, associated with strong winds in Owens Valley, dust swirls were seen near

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