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 Title: Cyclone climatology of the Great Lakes Author(s): Angel, James R. Doctoral Committee Chair(s): Isard, Scott A. Department / Program: Geography Discipline: Geography Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Physical Geography Physics, Atmospheric Science Abstract: Cyclones are an important feature of the Great Lakes region with significant impacts on ice cover, thermal structure, water quality, aquatic life, shipping, and shoreline property. For this research, a historical cyclone dataset was constructed for the period 1900 to 1990. This dataset was used to address the following five research topics: (a) the trends and fluctuations in the characteristics of cyclones, (b) the balance between cyclone frequency and intensity, (c) the sensitivity of cyclone characteristics to climate variables, particularly temperature and precipitation regimes, (d) the preferred tracks of cyclones passing over the region and changes over time, and (e) the influence of the Great Lakes on passing cyclones.The historical dataset was constructed from those cyclones with a central pressure $\leq$992 hPa when they were in the Great Lakes region. An extensive search of the climatological literature suggests that this is the first study to document a statistically significant increase in the frequency of strong cyclones over the Great Lakes during the 20th century in both November and December. This is a time of year when Great Lakes cyclones cause important economic damage (40% of the NOAA Storm Damage reports associated with cyclones occurred in those two months). Studies of the impacts of future climate change in the region generally assume that the cyclone frequency will not change over time. The results of this research suggest that this assumption is invalid. The increase in the frequency of strong cyclones in the Great Lakes region for November and December is believed to be the result of a general increase in intensity of all cyclones, which yielded more cyclones in the strong cyclone category.An analysis of changes in cyclone characteristics, temperature, and precipitation yields a positive relationship between cyclone frequency and precipitation. This relationship should be useful in climate change studies and for applications with the NWS long-range forecasts. This research also provides climatological evidence (as opposed to case studies or models) of the important influence of the Great Lakes on passing cyclones. During the unstable season, cyclones accelerate into the region, slow and deepen over the lakes, and then return to their prior speed and rate of deepening after they exit the region. The influence of the Great Lakes on passing cyclones is important not only during the unstable season (October-February), but also in late spring and early summer. Issue Date: 1996 Type: Text Language: English URI: http://hdl.handle.net/2142/20820 ISBN: 9780591087734 Rights Information: Copyright 1996 Angel, James Randal Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9702447 OCLC Identifier: (UMI)AAI9702447
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