The Connection between Drought and Blocking High Pressure Areas
Bachelor of Science (B.Sc.)
Blocking high-pressure areas are stationary weather systems that lead to elevated temperatures in summer and often cause extreme heat waves (Pfahl and Wernli, 2012). In addition, such high-pressure areas are typically accompanied by sinking air masses, cloudless skies and thus drought (see figure below). While the link between high pressure weather situations and temperature extremes is relatively well understood and quantified, there have been few studies to date on linking blocking high pressure areas with dry periods. However, a better understanding of the dynamic processes that favour drought is particularly needed in the context of anthropogenic climate change, which could lead to more pronounced droughts in many regions (Dai, 2013).
In this thesis a simple statistical method (by Pfahl and Wernli, 2012) is used to quantify the spatial relationship between blocking high pressure layers and drought. Based on reanalysis data, an objective index for blocking high pressure areas is linked to one or more drought indices (e.g. according to Byun and Wilhite, 1999).
Prerequisites for this work are interest in the atmospheric water cycle and climatological evaluations. Basic knowledge of a script language (R, Python) that can be used for data evaluation is advantageous, but can also be acquired during the work.
Supervisor: Stephan Pfahl
- Byun, H.-R. and D. A. Wilhite, 1999: Objective quantification of drought severity and duration. J. Climate 12, 2747-2756.
- Dai, A., 2013: Increasing drought under global warming in observations and models. Nature Clim. Change 3, 52-58, doi:10.1038/NCLIMATE1633.
- Pfahl, S. and H. Wernli, 2012: Quantifying the relevance of atmospheric blocking for co-located temperature extremes in the Northern Hemisphere on (sub-)daily time scales. Geophys. Res. Lett.39, L12807, doi:10.1029/2012GL052261.
Hinweis: Das Thema kann auch im Rahmen einer Masterarbeit bearbeitet werden.