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

higher altitudes (e.g., Siskind 2014 ). Thereby, the wind field and the thermal structure of the middle atmosphere are modified (e.g., Lindzen 1981 ; Holton and Alexander 2000 ). Internal gravity waves have been measured and analyzed with a large variety of active and passive remote sensing techniques as well as with in situ observations. These observational tools include airborne and ground-based lidars (e.g., Alexander et al. 2011 ; Dörnbrack et al 2002 ; Rauthe et al. 2008 ; Williams et al

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Stephen D. Eckermann, Jun Ma, Karl W. Hoppel, David D. Kuhl, Douglas R. Allen, James A. Doyle, Kevin C. Viner, Benjamin C. Ruston, Nancy L. Baker, Steven D. Swadley, Timothy R. Whitcomb, Carolyn A. Reynolds, Liang Xu, N. Kaifler, B. Kaifler, Iain M. Reid, Damian J. Murphy, and Peter T. Love

based on standard deviations of reanalyzed temperature differences with respect to independent MLT measurements (SOFIE and DLR lidar). By contrast, HYBRID runs weighted MLT observations and backgrounds more realistically via more representative errors in MLT temperature backgrounds from ensemble forecasts (see Fig. 10c ). These findings, while specific to the greater New Zealand region during the 2014 austral winter, nevertheless suggest a need to reinvestigate and recalibrate static error

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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

system north of the North Island, with a strong pressure gradient toward the south leading to a strong westerly flow (W regime; Fig. 2c ). The latter flow regime is prone to excite mountain waves and was found for 9.8% of the reanalyses. It prevailed for some consecutive days only at the end of July and beginning of August, after the aircraft deployment concluded [ground-based lidar and radiosonde observations continued through this period at Lauder; see Kaifler et al. (2015) and Ehard et al

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

-based lidar observations in the lee of New Zealand’s Alps during DEEPWAVE revealed enhanced gravity wave activity in the stratosphere and mesosphere, which lasted about 1–3 days and alternated with quiescent periods ( Kaifler et al. 2015 ). The gravity wave forcing due to passing weather systems, the appearance of tropopause jets, and the middle atmosphere wave response were all observed with a similar frequency and duration of 2–4 days ( Fritts et al. 2016 ; Gisinger et al. 2017 ). The episodic nature

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