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Andreas Dörnbrack

. East of 30°E, the low-level winds became more southerly. The polar-front jet at 300 hPa had developed above a region of enhanced middle- and lower-tropospheric baroclinicity, the polar front as seen in Fig. 1b . This upper-level jet streak had a large along-stream extent and was nearly zonally oriented at 45°N and V H > 70 m s −1 in its core ( Fig. 2b ). During the considered period, the polar-front jet bent and advanced southward in conjunction with the deepening upper-level trough. Similar to

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Mozhgan Amiramjadi, Ali R. Mohebalhojeh, Mohammad Mirzaei, Christoph Zülicke, and Riwal Plougonven

are orography, convection, and coupled jet and front systems (e.g., Plougonven and Zhang 2014 ), which are mainly located in the troposphere. Based on their sources, the IGWs are thus classified into “orographic” and “nonorographic” (e.g., Kim et al. 2003 ) and dealt with separately in IGW parameterization schemes as they have distinct characteristics and impacts ( McLandress et al. 2013 ). Through their sources, the nonorographic IGWs are connected to the large-scale flow which is dominantly

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Fabienne Schmid, Elena Gagarina, Rupert Klein, and Ulrich Achatz

Abstract

Idealized integral studies of the dynamics of atmospheric inertia-gravity waves (IGWs) from their sources in the troposphere (e.g., by spontaneous emission from jets and fronts) to dissipation and mean-flow effects at higher altitudes could contribute to a better treatment of these processes in IGW parameterizations in numerical weather prediction and climate simulation. It seems important that numerical codes applied for this purpose are efficient and focus on the essentials. Therefore a previously published staggered-grid solver for f-plane soundproof pseudo-incompressible dynamics is extended here by two main components. These are 1) a semi-implicit time stepping scheme for the integration of buoyancy and Coriolis effects, and 2) the incorporation of Newtonian heating consistent with pseudo-incompressible dynamics. This heating function is used to enforce a temperature profile that is baroclinically unstable in the troposphere and it allows the background state to vary in time. Numerical experiments for several benchmarks are compared against a buoyancy/Coriolis-explicit third-order Runge-Kutta scheme, verifying the accuracy and efficiency of the scheme. Preliminary mesoscale simulations with baroclinic-wave activity in the troposphere show intensive small-scale wave activity at high altitudes, and they also indicate there the expected reversal of the zonal-mean-zonal winds.

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Tyler Mixa, Andreas Dörnbrack, and Markus Rapp

times. Gravity waves with short horizontal wavelengths are generally not included in global circulation models due to their high resolution requirements and their limited influence according to linear gravity wave theory. Linear theory for stationary mountain waves predicts a cutoff wavelength of λ x cutoff = 2 πu / N ≳ 30–50 km inside the polar night jet (PNJ) ( Schoeberl 1985 ). This cutoff suggests a widespread existence of turning levels for mountain waves with λ x ≲ 30 km in the winter

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Sonja Gisinger, Andreas Dörnbrack, Vivien Matthias, James D. Doyle, Stephen D. Eckermann, Benedikt Ehard, Lars Hoffmann, Bernd Kaifler, Christopher G. Kruse, and Markus Rapp

tropospheric jet streams generate vertically propagating gravity waves in the troposphere and lower stratosphere ( Smith 1979 ; Gill 1982 ; Baines 1995 ; Fritts and Alexander 2003 ; Nappo 2012 ; Sutherland 2010 ; Plougonven and Zhang 2014 ). Through their far-field interactions, gravity waves constitute an important coupling mechanism in Earth’s atmosphere. The associated redistribution of momentum and energy controls the global middle-atmospheric circulation ( Dunkerton 1978 ; Lindzen 1981 ). To

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David C. Fritts, Ronald B. Smith, Michael J. Taylor, James D. Doyle, Stephen D. Eckermann, Andreas Dörnbrack, Markus Rapp, Bifford P. Williams, P.-Dominique Pautet, Katrina Bossert, Neal R. Criddle, Carolyn A. Reynolds, P. Alex Reinecke, Michael Uddstrom, Michael J. Revell, Richard Turner, Bernd Kaifler, Johannes S. Wagner, Tyler Mixa, Christopher G. Kruse, Alison D. Nugent, Campbell D. Watson, Sonja Gisinger, Steven M. Smith, Ruth S. Lieberman, Brian Laughman, James J. Moore, William O. Brown, Julie A. Haggerty, Alison Rockwell, Gregory J. Stossmeister, Steven F. Williams, Gonzalo Hernandez, Damian J. Murphy, Andrew R. Klekociuk, Iain M. Reid, and Jun Ma

= flight level, SI = South Island, CW = convective waves, FWs = frontal waves, SO = Southern Ocean. IOPs are shown in the context of the large-scale ECMWF horizontal winds from 0 to 80 km in Fig. 4 (top). The dominant feature is the polar night jet with a maximum wind often exceeding 100 m s −1 at ∼50–60 km that is presumably modulated in strength by PWs on time scales of ∼5–10 days. The poleward jet associated with frontal systems exhibits episodic maxima of ∼30–50 m s −1 at ∼8–12 km on similar

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Mahnoosh Haghighatnasab, Mohammad Mirzaei, Ali R. Mohebalhojeh, Christoph Zülicke, and Riwal Plougonven

Alexander 2003 ) over long distances and interacting with other phenomena through, for example, triggering convection. Previous observational and numerical studies have shown several sources for IGWs as orography, convection, shear instability, jet streams, and fronts (e.g., Uccellini and Koch 1987 ; Eckermann and Vincent 1993 ; O’Sullivan and Dunkerton 1995 ; Guest et al. 2000 ; Plougonven and Snyder 2007 ). The IGWs affect the atmospheric general circulation through breaking and dissipation by

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Mohammad Mirzaei, Ali R. Mohebalhojeh, Christoph Zülicke, and Riwal Plougonven

wave polarization relations. Previously, the HDA has been applied by Zülicke and Peters (2008) and Mirzaei et al. (2014) for the validation of a bulk parameterization of IGWs generated by jets, fronts, and convection. As its name suggests, the HDA’s working rests on certain assumptions on the wave field like the presence of a locally dominant wavenumber and sufficient separation with the large-scale balanced flow. By construction, the HDA performs well in regions of space filled by the coherent

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Martina Bramberger, Andreas Dörnbrack, Henrike Wilms, Steffen Gemsa, Kevin Raynor, and Robert Sharman

-air turbulence (CAT). Well-known generation processes of turbulence affecting aircraft at cruising altitudes comprise thunderstorms, strong wind shears related to upper-level fronts and jet streams, unbalanced flow, and breaking mountain waves (e.g., Vinnichenko et al. 1980 ; Lester 1993 ; Wolff and Sharman 2008 ; Lane et al. 2012 ; Sharman et al. 2012b ). Considering the generation process, turbulence directly related to breaking mountain waves is referred to as mountain wave turbulence (MWT) ( Sharman

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Gergely Bölöni, Bruno Ribstein, Jewgenija Muraschko, Christine Sgoff, Junhong Wei, and Ulrich Achatz

resulting in a constant buoyancy frequency . This implies a reference density profile where is the density scale height. Some of the test cases involve a prescribed background jet as an initial mean flow with a half-cosine wave shape: where is the maximal magnitude of the jet initialized at height , and is the width (i.e., vertical extent) of the half-cosine shape. In these cases, the wave-induced mean flow is diagnosed as : that is, the initial mean wind is subtracted from the total mean wind

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