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MI
Meteorological Institute

Photo: NARVAL Mission 2013/14, UHH and MPI-M

Bachelor/Master Topics

The Atmospheric Dynamics group offers a broad range of Bachelor and Master topics in the fields of atmospheric dynamics, its numerical analyses, and prediction at many scales. The topics are derived from the current research interests of the group, which encompass the following interrelated themes central to modern meteorology:

  • Waves in the atmosphere and their role in the weather and climate formation
  • Climate modelling and climate change
  • Extreme weather events
  • Earth’s energy cycle and energy pathways in the atmosphere
  • Analysis of the weather patterns
  • Predictability, model errors, and biases
  • Mathematical aspects of atmospheric dynamics

In our work, we combine statistical methods and novel diagnostics approaches. Typically, MS/Ba research is based on observation and analysis data and a hierarchy of numerical models, with complexity ranging from toy models to full-scale climate models. For mathematically-minded students, a number of problems coalescing meteorology with geometry, analysis, and statistics is available. Get in touch with us to discuss various open topics as well as possibilities to work as a student assistant (Hiwi).

Open topics for BSc/MSc theses:

1. Tropical circulation in forecasts by ML models: Recent rise of machine learning (ML) - based forecasts and their success provides opportunity to understand model errors in classical, physical equations - based forecasts. This work will compare the physics-based and ML-based forecasts of the ECMWF system, IFS and AIFS, respectively, focusing on large-scale equatorial waves and their forecast-error growth. The MSc thesis will also include the comparison of vertical velocities.

2. Global climatology of barotropic instability: Barotropic instability, which is related to the reversal of the meridional gradient of the absolute vorticity of the mean flow, can act as wave source and shape atmospheric variability at synoptic and larger scales. Examples include the African easterly jet and the quasi biennial oscillation. This thesis work includes statistical analysis of barotropic instability in ERA5 data in different atmospheric layers. The MSc thesis work also includes the computation of the wave growth rates using the available software.

3. Tropical kinetic energy spectra: Baroclinic instability is a well understood process leading to generation of kinetic energy in midlattude Rossby waves with synoptic scales most prone to the growth. The associated kinetic energy (KE) spectrum follows the power low k^(-3), where k is the horizontal wavenumber. In contrast, the slope of kinetic energy spectra in the tropics, where baroclinic instability is insignificant, is poorly understood. This MSc work will analyse tropical KE spectra in reanalysis data and possibly also models’ simulations and aim at coupling them to dynamical processes and physical forcing.

4. Making use of gravity wave observations in models: Global weather prediction models regularly show gravity wave (GW) signals in their analyses and forecasts. It is not clear how much GW signals in their analyses (if any) comes from assimilated observations, or it is all produced by the models. The recent Aeolus wind satellite measured wind profiles including large amplitude orographic gravity waves over Andes, the so-called hot spot of GWs in the global atmosphere. This work will compare GWs in ECMWF analyses with and without Aeolus winds to investigate the effect of observations on GW signals. The GW data are provided from MODES decomposition of the ECMWF analyses within the ongoing ESA project.

5. Effects of mean flow and vertical shear on the global atmospheric modes: Stable and unstable modes of the atmosphere are determined by the mean flow. Unstable modes play a pivotal role in the Earth's energy cycle as they are excited e.g. in the process of barotropic and baroclinic instability development. Stable modes have been linked to the most important quasi-periodic phenomena, such as North Atlantic Oscillation. Using the existing software, we will analyze the effects of the mean zonal flow in general and vertical shear in particular on the frequencies, growth exponents and spacial structures of the stable and unstable modes of the hydrostatic primitive equations. Further, we will apply the knowlegde and the software to the ERA5 data and link the stable and unstable modes to the observed dynamics, in particular, in the tropical region.

6. Forecasting and explaining tropical dynamics with help of machine learning: Machine learning (ML) methods have enjoyed remarkable success in atmospheric forecasting recently, with AI models' forecast skills reaching or even surpassing those of traditional physics based models. The critic often levelled at the ML algorithms is that they represent "black box" approach, which does not improve our understanding of the underlying physical processes and thus offers little to none scientific value. A new class of ML algorithms, so called entropy-optimal Sparse Probabilistic Approximation (sSPA) is free of this defect as it has explainability built-in. Recent article Groom et al (2024) applies sSPA to the ENSO forecast and demonstrates its superiority in comparison with "traditional" deep learing methods. We will apply sSPA to forecasting and understanding of the dynamical processes in the tropics using ERA5 data.

7. Modelling the climate of Amasia: On very long time scales, continental drift effects the Earth and its climate system together with changes in the orbital parameters, etc. It has been speculated that a supercontinent (Amasia) will form over the North Pole in about 50 to 200 million years (Nature 482, 208-211, 2012). This project will use a climate model of intermediate complexity (PlaSim) to analyse the climate system of this future planet Earth. The work will focus on particular aspects depending on the interest of the student.

8. The effect of the rotation rate on the atmospheric circulation: Beside other parameters, the atmospheric global circulation is controlled by rotation rate of the planet. For example, higher rotation rates result in an increasing number of atmospheric circulation cells.  Utilizing a global atmospheric circulation model (PUMA) the student analyses specific properties of the atmospheric circulation, like the energetics or the wave spectrum, in dependence of the planet's rotation rate.