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

Northern Hemisphere for which the biases were mainly reduced by implementation of mountain drag schemes, the parameterizations for the convectively generated IGWs proved specifically important in the Southern Hemisphere ( Chun et al. 2001 ) which is mainly covered by oceans. In this regard, Bossuet et al. (1998) implemented a simple scheme which relates the gravity wave momentum fluxes to the precipitation flux as an index of convective activity in the model. Following Lindzen (1981) , they applied

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Junhong Wei, Gergely Bölöni, and Ulrich Achatz

in a Lagrangian-mean reference frame the effect of GWs on the large-scale flow only appears in the momentum equation ( Andrews and McIntyre 1978 ). Application of this theory to an Eulerian-mean reference frame leads to a pseudomomentum-flux convergence by which the large-scale momentum is to be forced ( Andrews and McIntyre 1976 , 1978 ). As will be shown below this is at least justified if the large-scale flow is in geostrophic and hydrostatic balance. The direct scheme does not rely on any

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Tanja C. Portele, Andreas Dörnbrack, Johannes S. Wagner, Sonja Gisinger, Benedikt Ehard, Pierre-Dominique Pautet, and Markus Rapp

, wave momentum flux was accumulated during accelerating forcing due to conservation of wave action. In contrast, the flow over higher mountains generated gravity wave breaking at lower levels. Here, the accumulated maximum of the zonal momentum flux during the high-drag state occurred shortly after the time of maximum wind. So far, no real-world case studies exist investigating a mountain-wave field excited by transient low-level forcing and propagating into the middle atmosphere. In this case study

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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

reflected in the many seminal papers, reviews, and books describing these various processes. Examples of those addressing atmospheric GW topics of most relevance to DEEPWAVE science include the following: GW linear dynamics, propagation, conservation properties, and fluxes ( Hines 1960 ; Eliassen and Palm 1961 ; Bretherton 1969a , b ; Booker and Bretherton 1967 ; Gossard and Hooke 1975 ; Smith 1980 ; Nappo 2013 ); GW sources, characteristics, and responses ( Fritts 1984 ; Fritts and Alexander

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

solver (EULAG), as well as the GTG are employed to analyze HALO’s incident. a. Flux calculations HALO is equipped with the Basic HALO Measurement and Sensor System (BAHAMAS), which provides measurements of pressure, temperature, and the three wind components ( Giez et al. 2016 ). For this case study, data sampled at 10 Hz with a horizontal resolution of about 50 m are available. The measurement uncertainties are given in Table 1 and were calculated with the procedure described in Mallaun et al

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Jannik Wilhelm, T. R. Akylas, Gergely Bölöni, Junhong Wei, Bruno Ribstein, Rupert Klein, and Ulrich Achatz

is described by a quasigeostrophic potential vorticity that is affected by the GWs via pseudomomentum-flux convergence. For efficiency reasons, parameterizations use these theoretical results with drastic simplifications: (i) lateral GW propagation and the impact of horizontal mean flow gradients are ignored, and (ii) the time-dependent transient wave–mean flow interaction is replaced by an equilibrium picture where, because of the nonacceleration paradigm, GWs can only modify the resolved flow

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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

-Interim and MLS to obtain the quasi-stationary PW1 amplitude. Note that this analysis is done by using a 10-day window shifted by 1 day to eliminate the influence of migrating waves such as tides. Vertical energy fluxes ( ) over the SI at 4- and 12-km altitude were computed from mesoscale simulations of the Weather Research and Forecasting (WRF) Model with a horizontal resolution of 6 km. The model was initialized and continuously guided by MERRA2 reanalyses. To compute the perturbations of pressure and

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Claudia Christine Stephan, Cornelia Strube, Daniel Klocke, Manfred Ern, Lars Hoffmann, Peter Preusse, and Hauke Schmidt

2004 , Plougonven and Zhang 2014 ) and flow over orography (e.g., Lilly and Kennedy 1973 ; Dörnbrack et al. 1999 ; Eckermann and Preusse 1999 ; Jiang et al. 2004 ; Fritts et al. 2016 ). We here present the first intercomparison of GW pseudomomentum fluxes (GWMFs) in global convection-permitting simulations of three different state-of-the-art GCMs and those derived from satellite observations. Two simulations are performed with each model. The horizontal resolutions between each pair of

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Markus Rapp, Bernd Kaifler, Andreas Dörnbrack, Sonja Gisinger, Tyler Mixa, Robert Reichert, Natalie Kaifler, Stefanie Knobloch, Ramona Eckert, Norman Wildmann, Andreas Giez, Lukas Krasauskas, Peter Preusse, Markus Geldenhuys, Martin Riese, Wolfgang Woiwode, Felix Friedl-Vallon, Björn-Martin Sinnhuber, Alejandro de la Torre, Peter Alexander, Jose Luis Hormaechea, Diego Janches, Markus Garhammer, Jorge L. Chau, J. Federico Conte, Peter Hoor, and Andreas Engel

band of almost zonally symmetric GW activity and related momentum fluxes will be referred to as the “gravity wave belt.” F ig . 1. Illustration of the GW belt based on ERA5 temperature perturbations for (left) August and (right) September 2019 at a pressure levels of 10 hPa. Shown is | T′ | = ⁡ ( T 639 − T 106 ) 2 – (K; see “Models” section for details). The red oval marks the target area where airborne measurements were conducted during SOUTHTRAC-GW. While observational evidence for the GW belt

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

again statically stable. Following Lindzen (1981) and Becker (2004) , the turbulent fluxes are modeled by eddy viscosity and diffusivity so that small scales are damped more strongly than larger scales. The buoyancy equation, for example, is supplemented by a diffusion term with the turbulent eddy diffusivity coefficient . By Fourier transformation in space and integration over a short time interval , one obtains the following as change of the buoyancy amplitude: Employing identical eddy

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