Changes in Extratropical Cyclone Dynamics in the North Atlantic in a Warming Climate
Extratropical cyclones are a major control of weather and climate in the midlatitudes. Climate model simulations have been used to analyze the influence of global warming on extratropical cyclone dynamics. This study addresses the still open questions of whether cyclones will become more intense, wh...
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| Other Authors: | , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://refubium.fu-berlin.de/handle/fub188/36690 https://doi.org/10.17169/refubium-36403 https://nbn-resolving.org/urn:nbn:de:kobv:188-refubium-36690-7 |
| Summary: | Extratropical cyclones are a major control of weather and climate in the midlatitudes. Climate model simulations have been used to analyze the influence of global warming on extratropical cyclone dynamics. This study addresses the still open questions of whether cyclones will become more intense, what dynamic processes are responsible for these changes, and how this could impact the North Atlantic region. This study investigates extratropical cyclone dynamics over the two periods 1990-2000 and 2091-2100 using the Community Earth System Model Large Ensemble (CESM-LE) dataset. We analyze the storm response in the extended winter and summer seasons in the North Atlantic (NA) region. A Lagrangian cyclone detection is used to analyze the occurrence and spatial distribution of storm tracks. The evolution of cyclonic structures in a warming climate is studied with cyclone-centered composites. Likewise, a potential vorticity (PV) perspective is adopted to study the changes in the cyclone wind field near the surface. A trajectory analysis illuminates the contribution of diabatic processes to future changes of cyclone-associated PV anomalies. Firstly, through comparison with ERA-Interim reanalysis data, we find that the CESM-LE captures the current spatial distribution of intense cyclones adequately. Robust changes in cyclone occurrence and properties are found in the NA region for the end of the century. For instance, cyclone frequency decrease in a warming climate, whereas precipitation intensity increases. Projected intensity changes are generally small. Secondly, the structure of those cyclones whose intensities fall within the 90th percentile is studied via a composite analysis. Winter storm tracks of these most intense cyclones respond to climate warming with an eastward shift. This shift increases the risk of strong winds and extreme precipitation in western Europe. In winter, extratropical cyclones also exhibit structural changes that amplify precipitation intensity downstream and low-level wind flow to the ... |
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