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Stefano Serafin, Lukas Strauss, and Vanda Grubišić

intrusion of relatively dry air from the midtroposphere into Owens Valley during wave activity periods. The aspect of drying suggests a degree of similarity between WWEs in Owens Valley and foehn or chinook intrusions at other locations near major mountain ridges, for example, the European Alps. However, establishing analogies between WWEs and foehn or chinook episodes is not straightforward, as detailed in the following discussion. Fig . 14. Relationship between the cross-valley wind component u r

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Georg J. Mayr and Laurence Armi

of radio soundings downstream at Independence (I; two different locations) and upstream at LeMoore (L) and Visalia (V) and the Notch AWS on the sierra slope (square, 2557 m MSL) and the ISS2 AWS valley location (cross, 1498 m MSL) together with Kearsarge Pass (K, 3600 m MSL) are marked. The southern line is a typical flight path of the King Air during the morning flight, the northern one during the afternoon flight. The inset shows the larger region with the European Centre for Medium

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Thomas Raab and Georg Mayr

of the atmosphere both upstream and downstream of the Sierra Nevada. Analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) global model are used instead of directly comparing observations from, for example, radiosoundings. This method is more consistent, because suitable measurements were not available for all days, or not at representative locations. One drawback of this approach is that the model topography is much smoother and Owens Valley is not resolved (cf. Fig. 3

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Qingfang Jiang and James D. Doyle

its impact on orographic precipitation have been discussed in a number of model-based idealized and case studies ( Buzzi et al. 1998 ; Colle 2004 ; Cox et al. 2005 ; Colle et al. 2008 ). Low-level flow blocking occurs frequently over the upwind slopes of major barriers such as the Sierra Mountains and European Alps, which has significant implications for mountain waves. For uniformly stratified hydrostatic flow past a two-dimensional ridge or an isolated hill, it has been demonstrated that the

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Patrick A. Reinecke and Dale Durran

authors have compared in situ aircraft observations with model simulations of mountain waves over the European Alps during the Mesoscale Alpine Program (MAP; e.g., Doyle and Smith 2003 ; Volkert et al. 2003 ; Doyle and Jiang 2006 ). In these comparisons the models have been able to capture the general qualitative character of the mountain wave; however, their detailed evolution has not been adequately simulated. One persistent problem in both real-time and a posteriori forecasts is the tendency to

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Laurence Armi and Georg J. Mayr

temperature step of only 8 K. This weak cap is bounded above by a stagnant isolating layer. Such isolating layers are well known. They are an essential component of the idealized downslope solution of Smith (1985) and the solution of Winters and Armi (2014) , which also accounts for upstream blocking. They have also been observed at other locations such as the European and Dinaric Alps (e.g., Armi and Mayr 2007 ; Smith 1987 ). The formation of the isolating layer in a dynamically similar

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

Dynamics ‘94: Proceedings of the Second European Computational Fluid Dynamics Conference, 5–8 September 1994, Stuttgart, Germany, Vol. I, S. Wagner, J. Périaux, and E.-H. Hirschel, Eds., John Wiley & Sons, 1–23 . Frisch , U. , 1995 : Turbulence: The Legacy of A. N. Kolmogorov . Cambridge University Press, 296 pp . Fritts , D. C. , T. L. Palmer , Ø Andreassen , and I. Lie , 1996 : Evolution and breakdown of Kelvin–Helmholtz billows in stratified compressible flows. Part I: Comparison

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Laurence Armi and Georg J. Mayr

combination of changes on the large scale and the local scale made it possible for foehn to penetrate nearly 3 km down the Sierra Nevada slopes to the floor of Owens Valley. Figure 4 tracks the large-scale evolution at approximate crest height of the model Sierra Nevada in the European Centre for Medium-Range Weather Forecasts (ECMWF) global analyses in 6-hourly intervals from 1800 UTC through 1200 UTC (1000–0400 LST). Throughout this 18-h period, the large-scale flow upstream and across the sierras

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Yanping Li, Ronald B. Smith, and Vanda Grubišić

United States ( Whiteman 1982 ; Whiteman et al. 1989a , b ), the Aizu Basin and Ina Valley in Japan ( Kuwagata and Kimura 1995 ), and the Inn Valley in the European Alps ( Vergeiner and Dreiseitl 1987 ). In the Inn Valley, a diurnal surface pressure variation exceeding 160 Pa in September was detected. The pressure maximum in this valley occurs around 0600 LT at the innermost station, about an hour earlier than at the station at the valley exit. The daily vertically averaged temperature range is

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