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Percentage of six-hourly precipitation extremes (in 1989-2009) occurring simultaneously with a cyclone

Percentage of six-hourly precipitation extremes (in 1989-2009) occurring simultaneously with a cyclone
Bildquelle: Pfahl and Wernli, 2012

Cyclones and precipitation extremes

Stephan Pfahl, Edgar Dolores-Testillos
Master of Science (M.Sc.)
Bachelor of Science (B.Sc.)


Precipitation extremes in many regions of the world are associated with the occurrence of extratropical cyclones (Pfahl and Wernli, 2012; see figure below). Future changes in cyclone occurrence may thus potentially lead to changes also in extreme precipitation, which can have important consequences for society.

In this thesis, a simple statistical method that quantifies the co-occurrence of cyclones and extreme precipitation (see again Pfahl and Wernli, 2012) will be applied to model simulations of present-day and future climate (Kay et al., 2015; Yetella and Kay, 2017) in order to asses if (i) the model is able to reproduce the observed relationship between cyclones and precipitation extremes and (ii) this relationship is projected to change in a warmer future climate.

Prerequisites for this project are an interest in climate change and extreme precipitation as well as the willingness to communicate in English, as one of the supervisors does not speak German. The thesis may still be written in German. First experience with a scripting language (R, python) that will be used for data analysis can be helpful, but may also be obtained during the project.

Supervisors: Stephan Pfahl, Edgar Dolores Tesillos


  • Kay. J. E. et al., 2015: The Community Earth System Model (CESM) Large Ensemble Project: A community resource for studying climate change in the presence of internal climate variability. Bull. Amer. Meteor. Soc.96, 1333-1349, doi:10.1175/BAMS-D-13-00255.1.
  • Pfahl, S and H. Wernli, 2012: Quantifying the relevance of cyclones for precipitation extremes. J. Climate 25, 6770-6780, doi:10.1175/JCLI-D-11-00705.1.
  • Pfahl, S., P. A. O’Gorman, and E. M. Fischer, 2017: Understanding the regional pattern of projected future changes in extreme precipitation. Nature Clim. Change 7, 423-427, doi:10.1038/nclimate3287.
  • Yettella, V. and J. E. Kay, 2017: How will precipitation change in extratropical cyclones as the planet warms? Insights from a large initial condition climate model ensemble. Clim. Dyn. 49, 1765-1781, doi:10.1007/s00382-016-3410-2.

Note: Also eligible for Master thesis.