Decadal to centennial variability of daily wind over Northern Europe and its application to migrating dunes in the Baltic Sea region
The present work is focused on the analysis of the variability of extreme daily winds in Northern Europe, their relationship to mean winds and to large-scale climate patterns. In particular, this work has the aim of investigating the following four research questions: 1. Are mean wind statistics a u...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky
2015
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| Online Access: | http://nbn-resolving.de/urn:nbn:de:gbv:18-76995 https://ediss.sub.uni-hamburg.de/handle/ediss/6586 |
| Summary: | The present work is focused on the analysis of the variability of extreme daily winds in Northern Europe, their relationship to mean winds and to large-scale climate patterns. In particular, this work has the aim of investigating the following four research questions: 1. Are mean wind statistics a useful tool to draw conclusions on extreme wind statistics over the Baltic Sea? 2. What pressure patterns drive extreme westerly winds over the Baltic Sea? 3. What large-scale atmospheric parameters drive changes in the wind speed distribution over Northern Europe? 4. Can internal dune structures at the southern Baltic be applied to reconstruct the seasonal wind climate? The study uses different data sets ranging from the last decades, using observation-based reconstructions, to the last millennium, using model simulations: To answer the first research question the study compares the statistics of seasonal mean and daily extreme wind events over the Baltic Sea in three aspects: direction distribution, regional differences and seasonal variability. The results exhibited differences between mean and extreme wind events in all three facets. Therefore, the overall conclusion is that the hypothesis that the statistics of mean wind can serve as a proxy for statistics of extreme wind does not hold for the Baltic Sea region. The second part investigates daily wind extremes from west and south-west in the Baltic Sea region during winter and their relationship to circulation types. After identifying eight circulation types, four patterns showed relations to the frequencies of extreme west/southwest winds. The temporal evolution of three of these patterns showed clear imilarities to extreme west/south-west wind frequencies. The third part analyses the influence of potential large-scale atmospheric drivers to modulate the probability distribution of daily wind speed in winter over Northern Europe. The considered drivers are the mean temperature, the meridional temperature gradient and the North Atlantic Oscillation. The main ... |
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