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dc.contributor.authorSolbrekke, Ida Marieeng
dc.date.accessioned2014-08-27T12:31:46Z
dc.date.available2014-08-27T12:31:46Z
dc.date.issued2014-06-02eng
dc.date.submitted2014-06-02eng
dc.identifier.urihttps://hdl.handle.net/1956/8374
dc.description.abstractDuring the 25th of December 2011 a strong low pressure system struck Soutwestern Norway. This rapidly evolving system got the name "Dagmar". The aim of this thesis was to find out how the complex topography in Southern Norway affected the strong winds caused by Dagmar. An observational analysis was carried out, together with high resolution numerical simulations performed by the the Weather Research and Forcasting model (WRF). A linear wave model \citep{Barstad2005} was used to address the result form the WRF model and the observational analysis. In addition, the linear wave model was used to investigate how changes in key parameters like wind speed, wind direction, mountain height, and atmospheric stability could have influenced the WRF model results. The highest observed 10-m wind speed was measured at Kråkenes lighthouse, \SI{43.8}{\meter \per \second}, while the strongest wind gust was measured at Juvvasshø, \SI{64.7}{\meter \per \second}. The WRF model was set to simulate Dagmar with a realistic topography in Southern Norway. In addition, two other simulations were carried out: One where the topography of Southern Norway was smoothed out, and one run where the topography was completely removed. This was done to see the effect of Norway's complex topography on the strong winds caused by Dagmar. The flat topography simulation showed that the sting jet (strong winds to the south of Dagmar's core), which did not reach the coast in the topography-runs, reached inland when the mountain was removed. The reason for this retardation of the flow upstream of the mountain in the topography-runs was due to the presence of the mountain, and the corresponding high pressure region created on the windward side. The strength of this upstream wind shadow varied when the upstream wind direction changed. Another feature, present only in the mountain- runs, was a "left side jet", e.g., an region of accelerated air along the northwest coast. The linear wave model showed that the wind pattern was sensitive to changes in the key parameters, and varying the upstream wind direction from westerly to southwesterly was crucial for the exsistence of the left side jet.en_US
dc.format.extent11391932 byteseng
dc.format.mimetypeapplication/pdfeng
dc.language.isoengeng
dc.publisherThe University of Bergenen_US
dc.subjectDagmareng
dc.subjectTopographic effectseng
dc.titleTopographic Effects on Strong Winds in Southern Norway; A Case Study of the Storm Dagmaren_US
dc.typeMaster thesis
dc.rights.holderCopyright the author. All rights reserveden_US
dc.description.degreeMaster i Meteorologi og oseanografien_US
dc.description.localcodeMAMN-GEOF
dc.description.localcodeGEOF399
dc.subject.nus756213eng
fs.subjectcodeGEOF399


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