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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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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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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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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

underlying terrain. For example, mesoscale predictions of landfalling fronts were found to be very sensitive to small changes in incident flow, as deduced through simulations made with small modifications to the topography orientation by Nuss and Miller (2001) . Two-dimensional idealized adjoint ( Doyle et al. 2007 ) and ensemble ( Doyle and Reynolds 2008 ) model results indicate large sensitivity to the initial state as the mountain height increases, forcing wave breaking, where perturbation growth

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Qingfang Jiang and James D. Doyle

the United States. The valley is notorious for downslope windstorms, wave clouds, and rotors, which are typically associated with strong westerly winds impinging on the nearly north–south-oriented Sierra Nevada ridge. One of the first modern U.S. multiagency meteorological field programs, the Sierra Wave Project (SWP; Holmboe and Klieforth 1957 ; Grubišić and Lewis 2004 ) took place in the vicinity of Owens Valley in the early 1950s, during which a B-29 documented vertical velocities up to ±20 m

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

1997 ). The Louis (1979) surface layer parameterization, which makes use of a surface energy budget based on the force-restore method, is used to represent the surface fluxes. Subgrid-scale moist convection is represented using the Kain and Fritsch (1993) parameterization. The grid-scale evolution of the moist processes is predicted explicitly from budget equations for cloud water, cloud ice, raindrops, snowflakes, and water vapor ( Rutledge and Hobbs 1983 ). The short- and longwave radiation

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