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Bachelorarbeiten

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Themen für Bachelorarbeiten am Lehrstuhl Theoretische Meteorologie

Bei Interesse an Bachelorarbeiten im Lehrstuhl für Theoretische Meteorologie bitte bei Prof. G. Craig, Dr. C. Keil, Dr. K. Kober, Dr. M. Weissmann oder Dr. T. Janjic-Pfander nachfragen.

Nachfolgend eine Aufstellung konkreter Bachelorarbeitsthemen aus dem Lehrstuhl für Theoretische Meteorologie:

Linearity in convective-scale error growth

Hohenegger and Schär (2007a,b) estimated the linearity timescale of small-scale error growth in convective systems to a few hours. On the other hand they also showed that small amplitude errors grow much faster which contradicts the linearity assumption. Within the Bachelor thesis a series of different error growth experiments shall be performed using several initial error growth amplitudes and structures. The resulting growth rates and correlation timescales shall than be evaluated and compared.

References:

Hohenegger, C. and C. Schär, 2007a: Atmospheric predictability at synoptic versus cloud-resolving scales. Bulletin of the American Meteorological Society, 88 (11), 1783–1793.

Hohenegger, C. and C. Schär, 2007b: Predictability and error growth dynamics in cloud-resolving models. Journal of the Atmospheric Sciences, 64 (12), 4467–4478.

Kontakt und Betreuung: Tobias Selz

Berechnung der konvektiven Zeitskala auf der Basis von Beobachtungen

Konvektive Niederschläge können einerseits durch synoptisch-skalige Wettersysteme als auch durch lokale Prozesse ausgelöst werden. Die auf der Basis von Modelldaten berechnete konvektive Zeitskala ermöglicht die objektive Unterscheidung dieser unterschiedlichen Strömungsregime. Ziel dieser Arbeit ist die Berechnung der konvektiven Zeitskala basierend auf Beobachtungen.

Methoden und Vorgehen:

  1. Einarbeitung in das Thema
  2. Einarbeitung in den vorhandenen Programmcode (fortran) zur Berechnung von CAPE
  3. Bestimmung des beobachteten, stündlichen Niederschlags
  4. Berechnung der konvektiven Zeitskala
  5. Vergleich mit modellbasierten Werten

Kontakt und Betreuung: Christian Keil

Assimilation of surface wind measurements with KENDA-COSMO

Surface observations represent an important source of information for numerical weather forecasts but their use has proven to be difficult and their full potential is currently not exploited. A dense network of surface stations provide wind measurements over Germany. Using a kilometer-scale ensemble data assimilation (KENDA) system, these data can be assimilated into the COSMO-DE limited area model. However, due to a larger representativeness error in mountainous terrain wind observations are only used in Northern Germany where the terrain is sufficiently flat.

The aim of the project is to investigate the possibility of assimilating surface wind observations all over Germany using the KENDA-COSMO system. Error statistics of surface observations shall be investigated using already available COSMO-DE forecasts with a focus on the representativeness error of wind observations. These findings shall provide the basis for a series of data assimilation experiments computed with the local linux cluster.

The project requires a basic knowledge of programming and numerical weather prediction. The project will be performed in the framework of the HErZ Data Assimilation Branch at MIM.

Contact: Florian Harnisch, Martin Weissmann

Verification norms for evaluating observation impact

The knowledge of the impact of different observations on the accuracy of forecasts is crucial to optimize observing and data assimilation systems. Traditional methods as data denial experiments (i.e. rerunning the model for every possible configuration) can only be conducted occasionally due to their computational costs. For this reason, a new ensemble-based method to estimate the impact of observations has been implemented in the pre-operational DWD KENDA-COSMO ensemble data assimilation system in the framework of the HErZ Data Assimilation Branch at MIM.

The above picture shows exemplarily the spatial distribution of approximated impact of aircraft measurements (negative values green, positive values red). The size of the markers is proportional to the impact values. Similar figures shall also be plotted in the proposed thesis.

The task of the bachelor thesis is to compare different verification norms in order to accurately represent the impact of all the distinct observations. The work will rely on output of the operational COSMO-DE model and the experimental KENDA ensemble data assimilation system. Furthermore, the impact estimating tool, developed at LMU, will be extensively used.

The project requires basic knowledge of programming.

Contact: Matthias Sommer and Martin Weissmann

These projects would involve analyses of gridded analysis data and/or observational data and their interpretation.

Contact: Prof. Roger Smith (Room 230)
Email: roger.smith@lmu.de