• Bramberger, M., A. Dörnbrack, H. Wilms, S. Gemsa, K. Raynor, and R. Sharman, 2018: Vertically Propagating Mountain Waves—A Hazard for High-Flying Aircraft?. J. Appl. Meteor. Climatol., 57, 1957–1975,
  • Dörnbrack, A., Eckermann, S. D., Williams, B. P., & Haggerty, J. (2022). Stratospheric Gravity Waves Excited by a Propagating Rossby Wave Train—A DEEPWAVE Case Study, Journal of the Atmospheric Sciences, 79(2), 567-591.
  • Dörnbrack, A., Gisinger, S., Kaifler, N., Portele, T. C., Bramberger, M., Rapp, M., Gerding, M., Söder, J., Žagar, N., and Jelić, D.: Gravity waves excited during a minor sudden stratospheric warming, 2018. Atmos. Chem. Phys., 18, 12915-12931,
  • Dörnbrack, A., S. Gisinger, and B. Kaifler (2017), On the interpretation of gravity wave measurements by groundbased lidars, Atmosphere, 8, 49 (1-22), . (GW-TP /PACOG)
  • Dörnbrack, A., S. Gisinger, M. C. Pitts, L. R. Poole, and M. Maturilli (2017), Multilevel cloud structures over Svalbard, Mon. Weather Rev., 145, 1149-1159,
  • Gisinger, S., I. Polichtchouk, A. Dörnbrack, R. Reichert, B. Kaifler, N. Kaifler, M. Rapp, and I. Sandu, 2022: Gravity-Wave-Driven Seasonal Variability of Temperature Differences between ECMWF IFS and Rayleigh Lidar Measurements in the Lee of the Southern Andes, Journal of Geophysical Research: Atmospheres, 127, e2021JD036270.
  • Gisinger, S., A. Dörnbrack, V. Matthias, J. D. Doyle, S. D. Eckermann, B. Ehard, L. Hoffmann, B. Kaifler, C. G. Kruse, and M. Rapp, 2017: Atmospheric Conditions during the Deep Propagating Gravity Wave Experiment (DEEPWAVE), Mon. Wea. Rev. 145, 4249-4275.
  • Kaifler, N., Kaifler, B.; Ehard, B.; Gisinger, S.; Dörnbrack, A.; Rapp, M.; Kivi, R.; Kozlovsky, A. (2017): Observational indications of downward-propagating gravity waves in middle atmosphere lidar data, J. Atmos. Solar-Terr. Phys.,
  • Portele, T.C., A. Dörnbrack, J.S. Wagner, S. Gisinger, B. Ehard, P. Pautet, and M. Rapp, 2018: Mountain-Wave Propagation under Transient Tropospheric Forcing: A DEEPWAVE Case Study. Mon. Wea. Rev., 146, 1861–1888,
  • Pütz, C., Schlutow, M. and Klein, R.: Initiation of ray tracing models: evolution of small-amplitude gravity wave packets in non-uniform background. Theor. Comput. Fluid Dyn. (2019) 33: 509-535;
  • Rapp, M., Dörnbrack, A., and Kaifler, B. 2018: An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS radio occultation measurements and ECMWF model data, Atmos. Meas. Tech., 11, 1031-1048,, 2018.
  • Wagner, J., Dörnbrack, A., Rapp, M., Gisinger, S., Ehard, B., Bramberger, M., Witschas, B., Chouza, F., Rahm, S., Mallaun, C., Baumgarten, G., and Hoor, P., 2017: Observed versus simulated mountain waves over Scandinavia – improvement of vertical winds, energy and momentum fluxes by enhanced model resolution?, Atmos. Chem. Phys., 17, 4031-4052, (PACOG/GW-TP)

The  Publications show most detailed the research going on within the project. The abstracts of the most recent:

Initiation of ray tracing models: evolution of small-amplitude gravity wave packets in non-uniform background. Pütz, C., Schlutow, M. and Klein, R., Theoretical and Computational Fluid Dynamics 5, 2019

This study introduces a new computational scheme for the linear evolution of internal gravity wave packets passing over strongly non-uniform stratifications and background flows as found, e.g., near the tropopause. Focusing on linear dispersion, which is dominant at small wave amplitudes, the scheme describes general wave superpositions arising from wave reflections near strong variations of the background stratification. Thus, it complements WKB theory, which is restricted to nearly monochromatic waves but covers weakly nonlinear effects in turn. One envisaged application of the method is the formulation of bottom-of-the-stratosphere starting conditions for ray tracing parameterizations that follow nonlinear gravity wave packets into the upper atmosphere. A key feature in this context is the method’s separation of wave packets into up- and downward-propagating components. The paper first summarizes a multilayer method for the numerical solution of the Taylor–Goldstein equation. Borrowing ideas from Eliassen and Palm (Geophys Publ 22:1–23, 1961), the scheme is based on partitioning the atmosphere into several uniformly stratified layers. This allows for analytical plane wave solutions in each layer, which are matched carefully to obtain continuously differentiable global eigenmode solutions. This scheme enables rapid evaluations of reflection and transmission coefficients for internal waves impinging on the tropopause from below as functions of frequency and horizontal wavenumber. The study then deals with a spectral method for propagating wave packets passing over non-uniform backgrounds. Such non-stationary solutions are approximated by superposition of Taylor–Goldstein eigenmodes. Particular attention is paid to an algorithm that translates wave packet initial data in the form of modulated sinusoidal signals into amplitude distributions for the system’s eigenmodes. With this initialization in place, the state of the perturbations at any given subsequent time is obtained by a single superposition of suitably phase-shifted eigenmodes, i.e., without any time-stepping iterations. Comparisons of solutions for wave packet evolution with those obtained from a nonlinear atmospheric flow solver reveal that apparently nonlinear effects can be the result of subtle linear wave packet dispersion.

Gravity waves excited during a minor sudden stratospheric warming. Dörnbrack, A., Gisinger, S., Kaifler, N., Portele, T. C., Bramberger, M., Rapp, M., Gerding, M., Söder, J., Žagar, N., and Jelić, D., Atmos. Chem. Phys, 2018

An exceptionally deep upper-air sounding launched from Kiruna airport (67.82∘ N, 20.33∘ E) on 30 January 2016 stimulated the current investigation of internal gravity waves excited during a minor sudden stratospheric warming (SSW) in the Arctic winter 2015/16. The analysis of the radiosonde profile revealed large kinetic and potential energies in the upper stratosphere without any simultaneous enhancement of upper tropospheric and lower stratospheric values. Upward-propagating inertia-gravity waves in the upper stratosphere and downward-propagating modes in the lower stratosphere indicated a region of gravity wave generation in the stratosphere. Two-dimensional wavelet analysis was applied to vertical time series of temperature fluctuations in order to determine the vertical propagation direction of the stratospheric gravity waves in 1-hourly high-resolution meteorological analyses and short-term forecasts. The separation of upward- and downward-propagating waves provided further evidence for a stratospheric source of gravity waves. The scale-dependent decomposition of the flow into a balanced component and inertia-gravity waves showed that coherent wave packets preferentially occurred at the inner edge of the Arctic polar vortex where a sub-vortex formed during the minor SSW.

On the interpretation of gravity wave measurements by groundbased lidars, Dörnbrack, A., S. Gisinger, and B. Kaifler, Atmosphere (2017) .

This paper asks the simple question: How can we interpret vertical time series of middle atmosphere gravity wave measurements by ground-based temperature lidars? Linear wave theory is used to show that the association of identified phase lines with quasi-monochromatic waves should be considered with great care. The ambient mean wind has a substantial effect on the inclination of the detected phase lines. The lack of knowledge about the wind might lead to a misinterpretation of the vertical propagation direction of the observed gravity waves. In particular, numerical simulations of three archetypal atmospheric mountain wave regimes show a sensitivity of virtual lidar observations on the position relative to the mountain and on the scale of the mountain.

Atmospheric Conditions during the Deep Propagating Gravity Wave Experiment (DEEPWAVE), 2017; Gisinger, S., A. Dörnbrack, et al., Mon. Wea. Rev.,

This paper describes the results of a comprehensive analysis of the atmospheric conditions during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) campaign in austral winter 2014. Different datasets and diagnostics are combined to characterize the background atmosphere from the troposphere to the upper mesosphere. How weather regimes and the atmospheric state compare to climatological conditions is reported upon and how they relate to the airborne and ground-based gravity wave observations is also explored. Key results of this study are the dominance of tropospheric blocking situations and low-level southwesterly flows over New Zealand during June–August 2014. A varying tropopause inversion layer was found to be connected to varying vertical energy fluxes and is, therefore, an important feature with respect to wave reflection. The subtropical jet was frequently diverted south from its climatological position at 30°S and was most often involved in strong forcing events of mountain waves at the Southern Alps. The polar front jet was typically responsible for moderate and weak tropospheric forcing of mountain waves. The stratospheric planetary wave activity amplified in July leading to a displacement of the Antarctic polar vortex. This reduced the stratospheric wind minimum by about 10 m s−1 above New Zealand making breaking of large-amplitude gravity waves more likely. Satellite observations in the upper stratosphere revealed that orographic gravity wave variances for 2014 were largest in May–July (i.e., the period of the DEEPWAVE field phase).

Mountain-Wave Propagation under Transient Tropospheric Forcing: A DEEPWAVE Case Study, 2018, Portele, T.C., A. Dörnbrack, et al. Mon. Wea. Rev.,

The impact of transient tropospheric forcing on the deep vertical mountain-wave propagation is investigated by a unique combination of in situ and remote sensing observations and numerical modeling. The temporal evolution of the upstream low-level wind follows approximately a shape and was controlled by a migrating trough and connected fronts. Our case study reveals the importance of the time-varying propagation conditions in the upper troposphere and lower stratosphere (UTLS). Upper-tropospheric stability, the wind profile, and the tropopause strength affected the observed and simulated wave response in the UTLS. Leg-integrated along-track momentum fluxes () and amplitudes of vertical displacements of air parcels in the UTLS reached up to 130 kN m−1 and 1500 m, respectively. Their maxima were phase shifted to the maximum low-level forcing by ≈8 h. Small-scale waves ( km) were continuously forced, and their flux values depended on wave attenuation by breaking and reflection in the UTLS region. Only maximum flow over the envelope of the mountain range favored the excitation of longer waves that propagated deeply into the mesosphere. Their long propagation time caused a retarded enhancement of observed mesospheric gravity wave activity about 12–15 h after their observation in the UTLS. For the UTLS, we further compared observed and simulated with fluxes of 2D quasi-steady runs. UTLS momentum fluxes seem to be reproducible by individual quasi-steady 2D runs, except for the flux enhancement during the early decelerating forcing phase.

Observed versus simulated mountain waves over Scandinavia – improvement of vertical winds, energy and momentum fluxes by enhanced model resolution?, 2017; Wagner, J., Dörnbrack, A., Rapp, M., Gisinger, S., Ehard, B., Bramberger, M., et al., Atmos. Chem. Phys.,

Two mountain wave events, which occurred over northern Scandinavia in December 2013 are analysed by means of airborne observations and global and mesoscale numerical simulations with horizontal mesh sizes of 16, 7.2, 2.4 and 0.8km. During both events westerly cross-mountain flow induced upward-propagating mountain waves with different wave characteristics due to differing atmospheric background conditions. While wave breaking occurred at altitudes between 25 and 30km during the first event due to weak stratospheric winds, waves propagated to altitudes above 30km and interfacial waves formed in the troposphere at a stratospheric intrusion layer during the second event. Global and mesoscale simulations with 16 and 7.2km grid sizes were not able to simulate the amplitudes and wavelengths of the mountain waves correctly due to unresolved mountain peaks. In simulations with 2.4 and 0.8km horizontal resolution, mountain waves with horizontal wavelengths larger than 15km were resolved, but exhibited too small amplitudes and too high energy and momentum fluxes. Simulated fluxes could be reduced by either increasing the vertical model grid resolution or by enhancing turbulent diffusion in the model, which is comparable to an improved representation of small-scale nonlinear wave effects.