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Andreas Dörnbrack, Sonja Gisinger, Michael C. Pitts, Lamont R. Poole, and Marion Maturilli

1. Introduction The “picture of the month” as presented in this short contribution is not a photo of the sky spontaneously shot from a digital camera. The picture as displayed in Fig. 1 is a combination of spaceborne measurements by the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on board the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations ( CALIPSO ) satellite during one of several Arctic overpasses on 30 December 2015 and a high-resolution short

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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

numerical simulation and NCEP GFS = National Centers for Environmental Prediction Global Forecast System. MOTIVATIONS. GWs, or buoyancy waves, for which the restoring force is due to negatively (positively) buoyant air for upward (downward) displacements, play major roles in atmospheric dynamics, spanning a wide range of spatial and temporal scales. Vertical and horizontal wavelengths, λ z and λ h , respectively, for vertically propagating GWs are dictated by their sources and propagation conditions

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

et al. 2003 ; Hoskins and James 2014 ; De Vries et al. 2010 ; Davies 2015 ). The present study is concerned with the inverse problem of using the balanced omega equation to estimate diabatic forcing for the processes involving inertia–gravity waves (IGWs) associated with unbalanced motion and their parameterization. As gravity waves modified by Earth’s rotation ( Holton and Hakim 2013 ), the IGWs play an important role in the atmosphere by transferring momentum and energy ( Fritts and

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Benedikt Ehard, Peggy Achtert, Andreas Dörnbrack, Sonja Gisinger, Jörg Gumbel, Mikhail Khaplanov, Markus Rapp, and Johannes Wagner

. 2006 ), radars (e.g., Stober et al. 2013 ), airglow imagers (e.g., Suzuki et al. 2010 ), noctilucent cloud images (e.g., Pautet et al. 2011 ), satellite measurements (e.g., Alexander et al. 2008 ), radiosonde soundings (e.g., Dörnbrack et al. 1999 ; Zhang and Yi 2005 ), and rocket soundings (e.g., Rapp et al. 2004 ). However, these instruments are limited to particular altitude ranges and are only sensitive to a distinct part of the gravity wave spectrum ( Gardner and Taylor 1998 ; Preusse

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

et al. 2015 ; Irvine et al. 2016 ; Kim et al. 2016 ; Williams 2016 ). Moreover, at these altitudes atmospheric turbulence is the major reason for injuries to passengers and crew ( Sharman et al. 2012b ; Tvaryanas 2003 ). In particular, unpredicted turbulence outside clouds can be hazardous as it is neither visible to pilots nor detectable by standard onboard radars ( Sharman et al. 2012b ). This kind of turbulence that is not connected to clouds and thunderstorms is referred to as clear

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

larger-scale flow (e.g., Palmer et al. 1986 ; Lott and Miller 1997 ; Scinocca and McFarlane 2000 ) and the GW impact on the generation of high cirrus clouds and polar stratospheric clouds (e.g., Joos et al. 2009 ). Even more conspicuous than in the lower atmosphere, however, are GW effects in the middle atmosphere. The general circulation in the mesosphere is basically controlled by GWs ( Lindzen 1981 ; Holton 1982 ; Garcia and Solomon 1985 ). This also seems to be of relevance to both medium

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

transition from westerly to easterly winds with important consequences for the propagation and drag of planetary and synoptic waves ( Scaife et al. 2002 ). They also contribute to the forcing of the Brewer–Dobson circulation and thus to the transport of trace gases like ozone and water vapor ( Alexander and Rosenlof 1996 ). Convectively generated GWs are important for generating the quasi-biennial oscillation (QBO) in the tropics ( Labitzke 2005 ; Marshall and Scaife 2009 ), which has a strong influence

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