Extratropical Cyclones and Associated Climate Impacts in the Northeastern United States
There is growing concern that some aspects of severe weather could become more frequent and extreme across the northeastern United States (USNE) as a consequence of climate change. Extratropical cyclones and frontal systems are a common factor in a variety of severe weather hazards in the region. Th...
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DigitalCommons@UMaine
2020
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/3224 https://digitalcommons.library.umaine.edu/context/etd/article/4275/viewcontent/Simonson__Julia_Final_Aug._20_Grad_8.14.2020.pdf |
| Summary: | There is growing concern that some aspects of severe weather could become more frequent and extreme across the northeastern United States (USNE) as a consequence of climate change. Extratropical cyclones and frontal systems are a common factor in a variety of severe weather hazards in the region. This dissertation examines three types of meteorological events impacting the USNE – ice storms, heavy rainfall, and high-wind events. The first research topic utilizes the Weather Research and Forecasting (WRF) model in a case study of the December 2013 New England ice storm. In this analysis, a series of tests are conducted to examine how choice of planetary boundary layer physics and other factors affect the model skill in comparison to observations. The results show that near-surface variables are highly sensitive to model setup, highlighting the need for careful testing prior to use. The second research topic explores large-scale teleconnections associated with the documented increase in summer precipitation across the USNE over the past two decades. It is shown that the precipitation surplus occurs in likely teleconnection with increased frequency of high pressure blocking over Greenland. As the current generation of climate models do not correctly depict seasonal patterns or trends in precipitation for the USNE, identifying the association between Greenland blocking and recent precipitation changes across the USNE is crucial for understanding the shortcomings for climate projections for the region. The third research topic is an analysis of the frequency and intensity of mid-autumn wind storms in New England. Fall season storms can have dominant cold-season characteristics, while also being fueled by warm-season moisture sources or the result of an extratropical transition. While the results show an increase in storm total precipitation, there are no significant trends in overall wind storm frequency or intensity with respect to central pressure or surface wind speeds. Nevertheless, storm severity is only one ... |
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