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studium:themen_fuer_masterarbeiten_theo [2019/12/19 09:43]
keil 		studium:themen_fuer_masterarbeiten_theo [2023/10/05 09:04] (aktuell)
julien.savre
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 ===== Topics for master theses in the theory group ===== ===== Topics for master theses in the theory group =====
  
-Bei Interesse an **Masterarbeiten** im Lehrstuhl für Theoretische Meteorologie bitte bei Prof. G. Craig, Prof. T. Birner, Priv.Doz. T. Janjic ​oder Dr. C. Keil nachfragen. Nachfolgend eine Auswahl derzeit offener Themen:+Bei Interesse an **Masterarbeiten** im Lehrstuhl für Theoretische Meteorologie bitte bei Prof. G. Craig, Prof. T. Birner, Priv.Doz. T. Janjic, Dr. C. Keil or Dr. J. Savre nachfragen. Nachfolgend eine Auswahl derzeit offener Themen:
 \\ \\
 +
 +==== Does the stochastic perturbation scheme PSP2 improve precipitation forecasts in summer 2021?====
 +One of the key sources of uncertainty in state-of-the-art kilometric-scale NWP models comprises the model error. One approach to account for this uncertainty are stochastic schemes. The physically-based stochastic perturbation scheme, which has been developed at MIM in recent years, will be run in a parallel suite in the convection-permitting ICON-D2 ensemble at DWD for the summer 2021. 
 +
 +The aim of this project is to assess the performance of the PSP2 scheme in ICON-D2, both systematically over a season and in detail for high impact weather events.
 +
 +For more detailed information please contact Christian Keil or George Craig.
 +
 +====Dynamics-transport coupling in the stratosphere====
 +The stratospheric circulation is projected to change in response to a warming climate. A changing circulation can impact the transport of trace gases (ozone, water vapor and ozone destroying substances) in the middle and upper atmosphere. The project will focus on developing a better understanding of the dynamics-transport coupling in the stratosphere.
 +
 +Changes in the large-scale stratospheric dynamics and transport of trace gases will be investigated using a combination of theory, observations and numerical modeling. Key topics of investigation will be the subseasonal to climatological impact of stratospheric dynamical processes on the global distribution of tracers in the stratosphere. A hierarchy of climate models will be used.
 +
 +For more detailed information please contact Aman Gupta or Thomas Birner.
 +
 +====Large-scale impacts of convective clouds====
 +
 +Although convective clouds are much smaller than large-scale weather systems, they can be a major source of error in
 +weather forecasts because errors grow rapidly. Studying this error growth requires large ensembles of forecasts to
 +accurately represent the many ways that the weather situation can develop.
 +The aim of this project is to develop a simple numerical model that can represent the error growth processes, but is
 +inexpensive to run in large ensembles. Different model formulations will be designed, programmed in Python and evaluated
 +using advanced verification measures.
 +
 +For more detailed information please contact George Craig.
  
 ====Stratosphere-troposphere and climate dynamics==== ====Stratosphere-troposphere and climate dynamics====
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 Contact: Leonhard Scheck Contact: Leonhard Scheck
 +
 +/**
 ====Tropospheric moisture variability and the development of tropical convection==== ====Tropospheric moisture variability and the development of tropical convection====
  
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     ​     ​
 Contact: Julien Savre Contact: Julien Savre
 +**/
  
 ==== Applicability of lossy compression methods to meteorological applications==== ==== Applicability of lossy compression methods to meteorological applications====
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 Contact: Robert Redl Contact: Robert Redl
-\\ 
  
-Further themes are possible, please talk to Prof. G. Craig, Prof. T. Birner, Priv.Doz T. Janjic ​or Dr. C. Keil.+ 
 +==== Understanding and modelling the initiation of convection by propagating cold pool fronts ==== 
 +**WS 2023-2024** 
 + 
 +When convective clouds precipitate and rainfall evaporates before reaching the surface, the boundary layer may be sufficiently cooled to form a bubble of dense air spreading horizontally along the surface. The thermodynamic conditions at the centre of these so-called cold pools are generally not favorable to the further development of convective clouds, but the initiation of new clouds is facilitated along the propagating edges of these cold pools where warmer and moister air is lifted. Cold pools thus playing a considerable role in determining where convection occurs and how it organizes at the mesoscales, it is crucial to make sure that cold pools and, perhaps more importantly,​ their capacity to form new convective clouds are appropriately represented in Numerical Weather Prediction models. 
 + 
 +The objective of this project is to use a series of very high-resolution (< 1 km) numerical simulations of an idealized convective day in the tropics to gain a better understanding of the processes and parameters controlling the initiation of convection along cold pool fronts. In this project, we will particularly focus on two aspects of the problem: \\ 
 +1) how is convective initiation affected by the model'​s horizontal resolution? \\ 
 +2) how do surface conditions impact convective initiation?​\\ 
 +Answering these questions will contribute to the development of new methods/​parameterizations aiming at improving the representation of convective initiation in operational weather models. 
 + 
 +To successfully complete this project, you will be expected to carry out numerical simulations using the high-resolution model mentioned previously, and analyse the model outputs to relate convective initiation to various key atmospheric parameters. Identifying the true processes influencing convective initiation will require the use of advanced association metrics and statistical tests. 
 + 
 +Contact: //​[[julien.savre@lmu.de|Julien Savre]]//  
 + 
 + 
 +==== The organization of tropical convection with and without parameterized shallow clouds ==== 
 +**WS 2023-2024** 
 + 
 +Convective clouds over the tropical Oceans do not occur randomly in space but generally tend to self-organise thus forming mesoscale clusters of clouds. This process, known as convective self-aggregation,​ is driven by feedbacks between atmospheric moisture and the clouds themselves: convection tends to dry (by subsidence) the atmosphere in regions where the convective activity is weak or absent, while the atmosphere is moistened where convection takes place. The result is that the moist convective region becomes even more favorable to the development of convective clouds, whereas convection becomes effectively suppressed in the dry environment,​ thereby reinforcing the situation. 
 + 
 +Self-aggregation is known to occur in models when the domain size is sufficiently large to accommodate mesoscale cloud clusters and their dry environment,​ and when the horizontal grid spacing is coarse enough (> 1 km). One way to explain the dependency of convective aggregation on horizontal resolution is through the misrepresentation of shallow clouds in coarse models: these clouds are indeed too small to be explicitly represented at kilometer-scale resolutions but they are ubiquitous over the tropical Oceans and have a significant influence on moisture transport and the overall cloud scale circulation inside and just above the boundary layer.  
 + 
 +In this project, the exact role of shallow clouds on the development and maintenance of a self-aggregated state of convection will be explored. To that end, idealized numerical simulations of the tropical atmosphere in equilibrium will be performed under conditions favouring self-aggregation (large enough domain, coarse enough resolution). A simple parameterization representing the impact of shallow convection on the atmosphere will then be implemented and the simulations repeated to understand how the dynamics associated with these shallow clouds affects the emergence of convective self-aggregation. 
 + 
 +Contact: //​[[julien.savre@lmu.de|Julien Savre]]//  
 + 
 +============================================== 
 + 
 +Further themes are possible, please talk to Prof. G. Craig, Prof. T. Birner, Priv.Doz T. Janjic, Dr. C. Keil or Dr. J. Savre.
 \\ \\
    
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 Tel: 08153/​282553 ​ Tel: 08153/​282553 ​
 simon.unterstrasser@dlr.de simon.unterstrasser@dlr.de
 +
 +==== Investigation of tropical predictability in simulations using a stochastic convection scheme====
 +
 +In a series of model experiments (ICON) a stochastic convection scheme has been used to investigate the limits of atmospheric predictability that originate from the fast error growth that happens in moist convection and the spreading of this error upscale. However, although global simulations were performed this analysis has been restricted to the midlatitudes.
 +
 +The main idea behind this master thesis is to first re-apply the diagnostics that were used before to the tropics in addition with a basic evaluation of model performance and biases. In a second step diagnostics and phenomena that are specific to the tropics (eg. Kelvin waves, MJO) should be considered and their role in the error growth process could be investigated.
 +
 +This project requires interest in dynamical meteorology and modeling as well as a substantial amount of data analysis using python.
 +
 +Further reading:\\
 +Selz, 2019: Estimating the intrinsic limit of predictability using a stochastic convection scheme. (dataset description,​ midlatitude analysis)\\
 +Judth, 2020: Atmospheric Predictability of the Tropics, Middle Latitudes, and Polar Regions Explored through Global Storm-Resolving Simulations (Investigation of tropical predictability with a high-res model)
 +
 +Contact: Tobias Selz or George Craig
  
 **/ **/