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JetStreak

JetStreak

The influence of diabatic processes on jet streak evolution

Academic Advisor
Mona Burkenberger
Degree
Master of Science (M.Sc.)

Contents

In this master thesis, we will work on understanding the influence of diabatic processes on jet streak dynamics throughout their evolution. Mona Bukenberger and Stephan Pfahl will supervise the thesis.

Background

Locally, the mid-latitude jet stream is characterized by regions of enhancedwind speed, known as jet streaks (Palmén and Newton 1969). Intense precipitation and cyclogenesis often occur in the equatorward entrance and poleward exit quadrant of jet streaks. They also foster the developmentof extreme surface weather (Velden and Mills 1990; Winters et al.2020, and many others). In addition, jet streaks are relevant for air travel safety, since strong vertical wind shear, particularly on the poleward side of jetstreaks, promotes the development of clear-air turbulence (Lane et al. 2012; Williams2017). Because jet streaks are such relevant dynamical features, understanding their dynamics is an important research area.

Topic

The influence of moist processes, in particular cloud diabatic heating, on jet streaks, has received increasing attention in recent years. Multiple studies have shown that the tropopause-level divergent outflow of large-scale cloud formation can accelerate the jet, and most recently, Bukenberger et al (2026) have shown that clouds, radiation, and turbulencesystematically influence jet streak intensity when jet streaks are strongest.

The objectives of this thesis are to (a) establish a framework to extend upon this work in order to
(b) investigate how the impact of diabatic processes affects different phases of jet streak evolution, intensification, maintenance, and decay in a case study.

So far, no development-stage-conscious analysis has been on this topic.

Methods and data

The student working on this thesis will use Lagrangian analysis and ERA5 data, including the ERA5 short forecast data.
There will be some methodological development necessary to conduct the analysis for which we aim in this thesis: Building on the Lagrangian PV gradient method (Bukenberger et al, 2023), and combining it with object-centred methods will be part of this work.

What the thesis offers:

  • Close supervision

  • The possibility to develop your own analysis technique

  • A research question relevant to modern atmospheric dynamics

The thesis is a good fit for people who:

  • Have an interest in dynamics, in particular potential vorticity (PV) and quasi-geostrophic frameworks

  • Like to work on creative solutions for hard problems

  • Are interested in developing code (in python), though experience in tool development is not necessary. We’ll work on that collaboratively.

References:

Bukenberger, M., S. Rüdisühli, and S. Schemm, 2023: Jet stream dynamics from a potentialvorticity gradient perspective: The method and its application to akilometre-scale simulation. Quart. J. Roy. Meteor. Soc., 149, 2409–2432,https://doi.org/10.1002/qj.4513.

Bukenberger, M., N. Zilibotti, and S. Schemm, 2026: Diabatic processes in the four-quadrant jet streak model, Bull. Amer. Meteor. Soc., DOI: 10.1175/BAMS-D-25-0083.1

Lane, T. P., R. D. Sharman, S. B. Trier, R. G. Fovell, and J. K. Williams, 2012: Recentadvances in the understanding of near-cloud turbulence. Bull. Amer. Meteor.Soc., 93, 499–515, https://doi.org/10.1175/BAMS-D-11-00062.1.

Palmén, E. H., and C. W. Newton, 1969: Atmospheric Circulation Systems: TheirStructure and Physical Interpretation. Academic Press, 602 pp.

Velden, C. S., and G. A. Mills, 1990: Diagnosis of upper-level processes influencingan unusually intense extratropical cyclone over Southeast Australia.Wea. Forecasting, 5, 449–482, https://doi.org10.1175/1520-0434(1990)005<0449:DOULPI>2.0.CO;2.

Williams, P. D., 2017: Increased light, moderate, and severe clear-air turbulencein response to climate change. Adv. Atmos. Sci., 34, 576–586, https://doi.org/10.1007/s00376-017-6268-2.

Winters, A. C., D. Keyser, L. F. Bosart, and J. E. Martin, 2020: Composite synoptic-scaleenvironments conducive to NorthAmerican polar–subtropical jet superpositionevents. Mon. Wea. Rev., 148, 1987–2008, https://doi.org/10.1175/MWR-D-19-0353.1.