Sensitivitätsstudien und Analyse von Atmosphäre-Meereis-Wechselwirkungen mit dem regionalen Atmosphärenmodell HIRHAM4 auf Basis eines neu entwickelten beobachtungsgestützten unteren Modellantriebs während ausgewählter Sommer über der Arktis/Laptewsee

• Main Author: Görgen, Klaus
• Format: Doctoral or Postdoctoral Thesis
• Language: German
• Published: 2004
• Subjects: Geowissenschaften; ddc:550; Arctic; Laptev Sea; Arktis; Arktis*; laptev; Sea ice
• Online Access: https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/78; https://nbn-resolving.org/urn:nbn:de:hbz:385-1960; https://doi.org/10.25353/ubtr-xxxx-719d-d2da; https://ubt.opus.hbz-nrw.de/files/78/container.tgz; https://ubt.opus.hbz-nrw.de/files/78/20040517.pdf; https://ubt.opus.hbz-nrw.de/files/78/abstract.pdf; https://ubt.opus.hbz-nrw.de/files/78/abstrakt.pdf

By means of complex interaction-processes sea ice not only modifies the regional climate in the ocean-atmosphere-sea-ice system but also the general circulation of the atmosphere and the ocean's circulation. Besides a strong interannual variability sea-ice extent shows an arcticwide significant negative trend during the last two decades with maximum rates in spring and summer. These are often linked to (small-scale) processes in the Siberian Arctic and the Laptev Sea, respectively. The objective of this thesis is the expansion of the understanding of the processes concerning atmosphere-sea-ice interactions on the regional scale during the summer from 1979 to 2002 in the Arctic with a special emphasis on the Laptev Sea. To achieve this, numerical simulations of the regional climate model HIRHAM4 are used in conjunction with ground- and satellite-based observational data. A precondition for the numerical experiments and the realistic reproduction of atmospheric processes is an improved lower boundary forcing dataset for HIRHAM4 based on observational datasets, which is developed, validated and described. To investigate the effects of the sea-ice distribution, its properties and small-scale features on the atmosphere, HIRHAM4 is used in sensitivity studies systematically with different model settings, each of which incorporates the lower boundary forcing data in a different manner. Even little changes in the lower boundary forcing fields, while retaining the lateral boundary forcing, are sufficient to cause the model to produce significantly different atmospheric circulation patterns relative to the control simulations which use standard forcings and settings. Cyclone activity, which is a special focus of this study, is also altered. The mean atmospheric circulation patterns and the near-surface air temperature distribution can be reproduced more realistically with the new forcing dataset, which is shown by validation experiments with observational data. The biggest relative impact, besides an altered sea-ice ...