Large-Scale Atmospheric Drivers of Extreme Temperature Anomalies During Springtime in the Arctic

• Main Author: Barreng, Linnea
• Format: Bachelor Thesis
• Language: English
• Published: Uppsala universitet, Luft-, vatten- och landskapslära 2022
• Subjects: Meteorology; Temperature extremes; Arctic; Jet stream; Rossby waves; Spring; Meteorologi; Arktis; Extremväder; Jetström; Rossbyvågor; Vår; Meteorology and Atmospheric Sciences; Meteorologi och atmosfärforskning; Canada; Greenland; Ner; Pacific; Arktis*; Grönland; Siberia
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-482014

In this project warm extreme temperature events in the Arctic region during the spring months March, April and May were identified and analysed. In the analysis daily average NCEP reanalysis data from NOAA/OAR/ESRL PSL format was used. The extreme events were retrieved as the highest positive temperature anomalies from the climatological mean, and the synoptic scale plots for the 50 most extreme events were created to identify what patterns caused the extreme warming over the Polar region. By contouring the areas of statistical significance, the regions with a reoccuring pattern were identified. The results conclude that cyclonic activity over the high Arctic extending down over Greenland and northern Canada combined with anomalously high geopotential height over the north Pacific ocean, over the Arctic, and towards Siberia cause the high temperatures over the pole. A weaker Polar Vortex causes perturbations in the jet stream, ridges in these Rossby waves can act as a pathway for warm and moist air from the oceanic regions which has a warming effect in the Arctic. Further analysis can be done to investigate what teleconnections these spring-time extreme events have on a global scale. Under detta projekt har extremt varma temperaturevent i Arktisområdet under vårmånaderna Mars, April och Maj identifierats samt analyserats, genom att använda daglig medelvärdes NCEP reanalys data från NOAA/OAR/ESRL PSL i NetCDF format. De extrema händelserna identifierades genom att ta de största positiva temperaturavvikelserna från ett klimatologiskt medelvärde, storskaliga avvikelseplottar skapades för de 50 mest extrema händelserna för att kunna identifiera meteorologiska mönster som ovanligt varma Arktisdagar. De områden med mest återkommande mönsterna var statistiskt signifikanta och markerades med svarta konturer. Resultaten visar att lågtrycksaktivitet i Arktis som sträcker sig ner över Grönland samt norra Kanada kombinerat med höga geopotentialhöjdavvikelser över Stilla havet och Sibirien som sträcker sig upp mot ...