Urban cloud-to-ground (CG) lightning enhancement has been well documented for Atlanta, Georgia. This study builds on those investigations using modeling techniques. Numerous styles of analyses and regressions were conducted to establish patterns of CG lightning over the North Georgia region. CG lightning demonstrated clustering for all years of data: 1995-2008. However, the first strike of each day with lightning was randomly distributed according to a Poisson distribution, demonstrating the clustering is not due to permanent features. Attempts were unsuccessful to model CG lightning clusters as either a Matern or Thomas Poisson point process. Regressions of CG lightning with built environment covariates- FAA aviation obstacle locations and heights, population density, road length density, distance to the center of Atlanta, PM10 emissions data, distance to highways, and coal plant locations- as well as natural variables such as projected coordinate easting, northing, and NWS severe thunderstorm status were executed at resolutions of 1km, 2km, 4km, and 8km. Analyses demonstrated significantly higher flash frequency near FAA aviation obstacles. With an R2 value of 0.22, taller obstacles are struck more frequently than shorter obstacles. Regressions with road length density revealed little explanatory power (maximum R2=0.19), but demonstrated a positive correlation independent of scale. A multi-level visualization technique demonstrates the road length density correlation loses accuracy within dense urban corridors. Distance from Atlanta shows a negative correlation, but only at larger scales. Subsetting both regressions by direction reveals a significant difference on the Eastern and Western sides of Atlanta. Subsetting both regressions only to Gwinnett County, Georgia illustrates road length density has no correlation with flash frequency, and distance to Atlanta is still a scale dependent process. PM10 emissions analysis suggests that CG amplification is most likely to occur between 15 and 33µg/m3, but the data has significant flash frequency variability even within these PM10 levels. Immediate proximity to highways proves not to be a significant variable in modeling flash frequency at any resolution. Coal plant proximity has the potential to enhance CG flash frequency, but the inherent variability in frequency precludes a strong p-value compared to randomly generated areas. However, if the data is subset by flashes/day over 500, then the areas close to coal plants have significantly more lightning (p=2.19e-5). Using a subset of the twenty-five highest frequency flash days in three equal area study areas (Haralson and Polk Counties representing rural, Cobb County representing developed and upwind of Atlanta, and Gwinnett County representing downwind and developed) Mann-Whitney tests are completed to determine if NWS severe thunderstorm storms are significantly different in CG flash frequency. In each study area, the NWS severe thunderstorms are not significantly different in flash frequency than non-severe storms. This analysis also suggests spatial tendencies of high frequency storms in each area. This multi-scale analysis also suggests that when examining CG lightning, more than one scale of examination should be used. Some processes of lightning amplification appear to occur at very local scales (500m), whereas others are coarser (up to 8km). There appears to be no goldilocks scale of analysis for CG lightning. However, if only one resolution is to be used, 2km is recommended. / A Thesis submitted to the Department of Geography in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester, 2012. / June 20, 2012. / Atlanta, CG Lightning, ggplot, MAUP, NLDN, Urban Lightning / Includes bibliographical references. / James B. Elsner, Professor Directing Thesis; Victor Mesev, Committee Member; Tetsuo Kobayashi, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_183133 |
| Contributors | Strikas, Ona (authoraut), Elsner, James B. (professor directing thesis), Mesev, Victor (committee member), Kobayashi, Tetsuo (committee member), Department of Geography (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
Page generated in 0.0017 seconds