Project B06:
Impact of small-scale dynamics on UTLS transport and mixing

Brief Summary

Zonal-mean tracer transport through the UTLS is characterized by the mean residual Brewer-Dobson circulation (BDC) and it is modified by mixing due to turbulence and partly gravity waves (GWs). Both GWs and turbulence occur on scales which require to be parameterized in weather and climate models. However, available parameterizations fail to reliably describe the effects on tracers. With the overall goal of mending this situation we want to pursue the following core objectives:

1. We will further improve the newly developed GW model MS-GWaM in ICON to address the effects on tracers of the BDC, via corresponding diagnostics, and mixing, through passive-tracer simulations. In particular, we will focus on the description of the spontaneous-imbalance source, which is of major importance in the extratropical UTLS.
2. The direct coupling of MS-GWaM to tracers will be addressed systematically through idealized investigations. This will allow us to further improve the description of this coupling in ICON/MS-GWaM and to study the consequences with regard to UTLS tracer transport.
3. Current turbulence parameterizations do not take into account the complex nature of turbulence (non-homogeneous, anisotropic, non-Kolmogorov, patchy, and three-dimensional) in the strongly stratified UTLS. We therefore improve the corresponding approach in ICON using large-eddy simulations (LES) to quantify the transport and mixing in the UTLS and investigate the contribution of turbulent mixing in the UTLS.
4. We will validate Objectives 1. – 3. by using suitable observations and wave-resolving simulations. For this purpose we will analyze high-resolution airborne measurements for GW properties and GW occurrence frequency. This will be supplemented by GW resolving ICON simulations of baroclinic life cycles, the ensuing spontaneous GW emission and related tracer effects.

Members

Publications

Kim, Y.-H., G. S. Voelker, G. Bölöni, G. Zängl, and U. Achatz (2024): Crucial role of obliquely propagating gravity waves in the quasi-biennial oscillation dynamics. Atmospheric Chemistry and Physics 24 (5), 3297–3308. doi: 10.5194/acp-24-3297-2024.

Voelker, G. S., G. Bölöni, Y.-H. Kim, G. Zängl, and U. Achatz (2024): MS-GWaM: A 3-dimensional transient gravity wave parametrization for atmospheric models. Journal of the Atmospheric Sciences, doi: 10.1175/JAS-D-23-0153.1.

Listowski, C., C. C. Stephan, A. Le Pichon, A. Hauchecorne, Y.-H. Kim, U. Achatz, and G. Bölöni (2024): Stratospheric gravity waves impact on infrasound transmission losses across the International Monitoring System. Pure and Applied Geophysics, doi: 10.1007/s00024-024-03467-3.

Achatz, U., M. J. Alexander, E. Becker, H.-Y. Chun, A. Dörnbrack, L. Holt, R. Plougonven, I. Polichtchouk, K. Sato, A. Sheshadri, C. C. Stephan, A. van Niekerk, and C. J. Wright (2024): Atmospheric Gravity Waves: Processes and Parameterization. Journal of the Atmospheric Sciences 81 (2), 237–262. https://doi.org/10.1175/JAS-D-23-0210.1

Achatz, U., Y.-H. Kim, and G. S. Voelker (Nov. 2023): Multi-scale dynamics of the interaction between waves and mean flows: From nonlinear WKB theory to gravity-wave parameterizations in weather and climate models. Journal of Mathematical Physics 64 (11), 111101. doi: 10.1063/5.016518

Chouksey, M., C. Eden, G. T. Masur, and M. Oliver (2023): A comparison of methods to balance geophysical flows. Journal of Fluid Mechanics 971, A2. doi: https://doi.org/10.1017/jfm.2023.602.

Lachnitt, H.-C., P. Hoor, D. Kunkel, M. Bramberger, A. Dörnbrack, S. Müller, P. Reutter, A. Giez, T. Kaluza, and M. Rapp (2023): Gravity-wave-induced cross-isentropic mixing: a DEEPWAVE case study. Atmospheric Chemistry and Physics 23 (1), 355–373. doi: https://doi.org/10.5194/acp-23-355-2023.

Millán, L. F., G. L. Manney, H. Boenisch, M. I. Hegglin, P. Hoor, D. Kunkel, T. Leblanc, I. Petropavlovskikh, K. Walker, K. Wargan, and A. Zahn (2023): Multi-parameter dynamical diagnostics for upper tropospheric and lower stratospheric studies. Atmospheric Measurement Techniques 16 (11), 2957–2988. doi: https://doi.org/10.5194/amt-16-2957-2023.

Masur, G. T., H. Mohamad, and M. Oliver (2022): Quasi-convergence of an implementation of optimal balance by backward-forward nudging. Multiscale Modeling & Simulation 21 (2), 624–640. doi: https://doi.org/10.1137/22M1506018.

Bašták Ďurán, I., M. Sakradzija, and J. Schmidli (2022): The Two-Energies Turbulence Scheme Coupled to the Assumed PDF Method. Journal of Advances in Modeling Earth Systems 14 (5), e2021MS002922. doi: https://doi.org/10.1029/2021MS002922.

Kaluza, T., D. Kunkel, and P. Hoor (2022): Analysis of Turbulence Reports and ERA5 Turbulence Diagnostics in a Tropopause-Based Vertical Framework. Geophysical Research Letters 49 (20), e2022GL100036 2022GL100036, e2022GL100036. doi: https://doi.org/10.1029/2022GL100036.

Reilly, S., I. Bašták Ďurán, A. Theethai Jacob, and J. Schmidli (2022): An Evaluation of Algebraic Turbulence Length Scale Formulations. Atmosphere 13 (4), doi: https://doi.org/10.3390/atmos13040605.