Cloud-to-ground lightning data from the National Lightning Detection Network during the 14-year period 1989-2002 are used to create a warm season lightning climatology for the northern Gulf Coast. Days are separated into five flow regimes based on the orientation of the coastline and the low-level flow. Specifically, each day is classified into either a calm (less than 2.5 m s-1) or directional flow category based on the mean 1000-700 hPa vector wind data at Lake Charles and Slidell, Louisiana. Flash densities are calculated, and maps are created for daily, hourly, and nocturnal periods. The composite 24-hour and nocturnal flash density maps indicate an east-to-west decrease in lightning over the region. Flash densities for the 24-hour period are greatest over land, with relative maxima located near the major metropolitan areas of Houston, Lake Charles, Baton Rouge, New Orleans, Biloxi, and Mobile. Flash densities during the nocturnal period are largest over the coastal waters. Land breezes, warm and shallow Gulf of Mexico waters, and advection of land-forming convection are responsible for the nighttime offshore convection. Lightning across the northern Gulf Coast depends largely on the prevailing synoptic flow. The low-level flow controls the sea breeze, the dominant forcing mechanism during the warm season. Southwest flow is the most unstable and humid of the five regimes, and it exhibits the most flashes. In this case, sea breeze induced convection is located slightly inland from the coast. Northeast flow, being the driest and most stable of the regimes, exhibits the least amount of lightning. The large-scale flow holds the sea breeze along the coastline. Flash density maxima over urban areas are examined to determine the relationship between lightning and the low-level flow. Analyses reveal that these maxima result from interactions between the prevailing flow and one or more mesoscale circulations. Urban influences such as frictional convergence, heat island effects, and air pollution also play a role in the enhancements. Geographic features and local mesoscale circulations affect lightning across the northern Gulf Coast. Geographic features, including lakes, bays, marshes, swamps, and coastline orientations, interact with the low-level flow and mesoscale circulations, such as the sea breeze and lake breezes, to produce complex lightning patterns and distributions. This climatology is useful for operational meteorologists faced with the challenge of forecasting summertime convection and its resulting lightning. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Fall Semester, 2003. / November 10, 2003. / Meteorology, Climatology, National Lightning Detection Network, Convection / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Guosheng Liu, Committee Member; Philip Cunningham, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_176043 |
| Contributors | Stroupe, Jessica Raye (authoraut), Fuelberg, Henry E. (professor directing thesis), Liu, Guosheng (committee member), Cunningham, Philip (committee member), Department of Earth, Ocean and Atmospheric Sciences (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. |
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