Cyclonic Activity and its Influences on Antarctica
The Antarctic Ice Sheet is the largest single ice mass on earth. Future change of Antarctic surface mass balance potentially impacts global sea level. Therefore, investigations of future surface mass balance is highly relevant and also discussed by the "Intergovernmental Panel on Climate Change...
| Main Author: | |
|---|---|
| Other Authors: | , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2015
|
| Subjects: | |
| Online Access: | https://refubium.fu-berlin.de/handle/fub188/3145 https://doi.org/10.17169/refubium-7345 https://nbn-resolving.org/urn:nbn:de:kobv:188-fudissthesis000000100185-7 |
| Summary: | The Antarctic Ice Sheet is the largest single ice mass on earth. Future change of Antarctic surface mass balance potentially impacts global sea level. Therefore, investigations of future surface mass balance is highly relevant and also discussed by the "Intergovernmental Panel on Climate Change". While the role of future increase of atmospheric moisture content is already analysed in several studies, the influence of changing atmospheric circulation on Antarctic mass balance is underexplored. This thesis contributes to fill this gap. Extra-tropical cyclones make the main contribution of atmospheric moisture flux in the mid- and high-latitudes. For that reason this work investigates the possibility of objective identification and tracking of extra-tropical cyclones in the Sub-Antarctic region and its influence of moisture transport towards Antarctica. At first this is done for ERA Interim reanalysis. An estimation of methodical dependency of cyclone tracking algorithms is done by means of analysis of 15 different objective methodologies. Strong cyclones were selected and their impact on moisture transport is examined. A strong methodical dependency is found for the absolute number of identified cyclones, whereas spatial patterns of cyclone densities mainly agree. Major disagreements are found in Weddell and Ross Seas, where quasi-stationary systems occur. A good agreement, i.e. small methodical dependency, can be found for the identification of strong cyclones. Poleward moisture transport which is attributed to these strong systems is well represented by the different algorithms. Investigation of climate change signals of Southern Hemisphere cyclones is done by means of a multi-model ensemble of six coupled atmosphere-ocean general circulation models with nine simulations in total. Strong cyclones are also separately analysed. While each model simulates a significant decrease of cyclone tracks between 20° S and 90° S in the 21st century, seven of nine integrations show increasing strong tracks, whereas three ... |
|---|