Browsing Earth and Environmental Systems by Subject "Atmospheric Analogues"
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Using Analogues to Simulate Intensity, Trajectory, and Dynamical Changes in Alberta Clippers with Global Climate ChangeAlberta Clippers are extratropical cyclones that form in the lee of the Canadian Rocky Mountains and traverse through the Great Plains and Midwest regions of the United States. With the imminent threat of global climate change and its effects on regional teleconnection patterns like El Niño-Southern Oscillation (ENSO), properties of Alberta Clipper could be altered as a result of changing atmospheric circulation patterns. Since the Great Plains and Midwest regions both support a large portion of the national population and agricultural activity, the effects of global climate change on Alberta Clippers could affect these areas in a variety of ways. Despite this reasoning, relatively few studies have addressed Alberta Clippers, especially in comparison to the other North American storm tracks. In this study, the effects of global climate change on Alberta Clippers are examined by using atmospheric analogues chosen from 1950-2012 based on temperature and ENSO characteristics. Composite maps of regional MSLP at 12-hr intervals, 300mb vector wind and geopotential height at the time of cyclogenesis, and 850mb temperature and geopotential height patterns 36 hours after Clipper formation are constructed. Difference maps of 300mb geopotential height patterns between each of the analogues are also constructed. One-way ANOVA tests are also used to analyze Alberta Clipper latitude and longitude values at t=0, Clipper trajectory azimuths from t=0 to t=60, central MSLP values for these storms twelve hours after formation, and MSLP pressure gradients at t=24. The results from these tests indicate that, of the four analogues, the Cold and El Niño years are the most dissimilar, maintaining statistically significant differences in upper-level wind magnitude and starting longitude values. MSLP at t=12 is lower in the Cold storms than the El Niño storms, but statistical significance between these values is not quite achieved. Furthermore, geopotential height differences and their associated rate of change with respect to map distance indicate that the 300mb geopotential height patterns of the El Niño and Cold analogues are quite different from one another. The La Niña and Warm analogue years are different from one another with respect to latitude and longitude values of Alberta Clippers at cyclogenesis. Based on these results, the effects of temperature increase alone will not influence the properties of Alberta Clippers as much as changes in ENSO that could be caused by global climate change.