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

atmospheric applications is the second (hydrostatic) limit, for which the mesoscale-wave impact is the strongest. For instance, taking ( H m , L m ) = (1, 100) km and f / N * = 10 −2 , from (20) it is then found that ( H w , L w ) = (0.1, 1) km. Notably, this scale estimate is in good agreement with present-day local-area weather-forecast-code mesh distances (see section 1 ). For later reference, Table 1 provides an overview of the scales deduced in this section. It is worth noting that the

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Junhong Wei, Gergely Bölöni, and Ulrich Achatz

thus limit mesoscale predictability ( Zhang et al. 2007 ; Sun and Zhang 2016 ; Bierdel et al. 2018 ). The most important impact globally is because GWs can travel over large distances from their sources and transfer significant amounts of momentum and energy to high altitudes, which contributes to the forcing of the circulation and the variability of the middle atmosphere ( Holton and Lindzen 1972 ; Houghton 1978 ; Lindzen 1981 ; Dunkerton 1997 ; Richter et al. 2010 ; Limpasuvan et al. 2012

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

fine to capture a major fraction of the GW spectrum (e.g., Beres et al. 2004 ; Choi and Chun 2011 ). GWs in high-resolution (~4 km) simulations of regional mesoscale models, such as the Weather Research and Forecasting (WRF) Model, can have a high degree of realism ( Grimsdell et al. 2010 ; Orr et al. 2015 ; Stephan and Alexander 2015 ; Stephan et al. 2016 ). In the light of ever-increasing computational capabilities, the above challenges have served as a strong motivation to devise global

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

this fuzziness, there is no exact balance and no exact wave–vortex decomposition. Given the constraints set by this fundamental limitation, the waves and vortical flows can only be decomposed in an approximate sense, which can be sufficient for practical purposes. The current work aims to compare the measures of IGW activity coming from the HDA with those of the WVD methods in the idealized numerical simulations of the dry and moist baroclinic instability by the Weather Research and Forecasting

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

incorporating the gravity waves generated by convection. In this way, they carried out a dry idealized simulation using the Weather Research and Forecasting (WRF) Model forced by diabatic heating field obtained by converting radar precipitation rates, and succeeded to reproduce the observed gravity waves associated with squall lines and mesoscale convective systems. In the energy-based parameterization of IGWs generated by nonorographic sources, including convection, proposed by Mirzaei et al. (2014) , a

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Mark Schlutow

Mech. , 826 , 1034 – 1065 , https://doi.org/10.1017/jfm.2017.459 . 10.1017/jfm.2017.459 Schlutow , M. , E. Wahlén , and P. Birken , 2019 : Spectral stability of nonlinear gravity waves in the atmosphere . Math. Climate Wea. Forecasting , 5 , 12 – 33 , https://doi.org/10.1515/mcwf-2019-0002 . 10.1515/mcwf-2019-0002 Vadas , S. L. , and D. C. Fritts , 2002 : The importance of spatial variability in the generation of secondary gravity waves from local body forces . Geophys. Res

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Nonlinear Simulations of Gravity Wave Tunneling and Breaking over Auckland Island

Tyler Mixa, Andreas Dörnbrack, and Markus Rapp

winter MLT. The continued absence of this MLT GWD source in global and mesoscale climate modeling suggests that addressing gravity wave tunneling dynamics is a viable approach to improve the accuracy of climate modeling in the Southern Hemisphere. Acknowledgments This research was conducted within the scope of the German research initiative Role of the Middle Atmosphere in Climate (ROMIC) under Grant 01LG1206A by the German Ministry for Education and Research. Funding was also provided by the German

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