A Climatology of the Sea Breeze Front in the Coastal Carolinas and Georgia.

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Title: A Climatology of the Sea Breeze Front in the Coastal Carolinas and Georgia.
Author: Crouch, Andrew David
Advisors: Dr. Sethu Raman, Committee Member
Dr. Gary Lackmann, Committee Member
Dr. Allen Riordan, Committee Chair
Abstract: The sea breeze circulation forms as a result of differential heating across the land-sea surface interface. The resultant pressure gradient force (PGF) induces an onshore flow at the surface and a return flow higher in the atmosphere. The sea breeze front is a reflection of this circulation, a boundary between the cool, moist, maritime air mass advancing landward and the warm, dry ambient air mass in place over inland areas. Studies have shown that the circulation forms more often in the spring and summer months when the temperature difference between land and sea surfaces is greatest. The following study is based on the analysis of satellite imagery and standard hourly measurements of air temperature, dewpoint, wind speed, and wind direction recorded at four coastal sites: Savannah, GA, Charleston and Myrtle Beach, SC, and Wilmington, NC. One of the objects of this study is to establish specific values associated with the changes induced by passage of the sea breeze front, and to examine differences in the station-to-station incarnation of the sea breeze circulation. Variability from station to station in the nature and timing of sea breeze frontal passage was found to be a function of relative proximity to the coast. For example, sea breeze frontal passage was found to occur earliest at Myrtle Beach (the closest station to the coast), around 1300 LST on average. Savannah, the farthest of the four coastal sites from the water, was affected by the sea breeze last, with an average passage time of between 1630 and 1700 LST. Previous studies indicate that the extent to which the circulation and associated front penetrate inland is usually on the order of about 20-60 km. GOES satellite imagery was accumulated from the North Carolina State Climate Office and analyzed with GIS (Geographic Information System) software for the purpose of determining the inland horizontal extent of the sea breeze circulation. Penetration distances of 20-40 km were common, but occasionally the sea breeze penetrated as far as 80 to 120 km. The second part of this study attempts to develop a scheme for the prediction of the development and evolution of the sea breeze front. The factors most significant to this prediction include the synoptic wind flow regime and values for the temperature difference between land and sea surfaces. North American Regional Reanalysis data were downloaded and analyzed to gather daily geostrophic wind vectors. Water temperature data were collected and compared with air temperature measurements to determine the temperature difference, the driving mechanism for sea breeze development. Data for the Myrtle Beach site were analyzed first to provide a framework for the other stations because of relative completeness and reliability of the data sources. At Myrtle Beach, ninety percent of sea breeze development occurred with land-sea temperature differences of 2.0 degrees Celsius or higher.
Date: 2006-11-08
Degree: MS
Discipline: Marine, Earth and Atmospheric Sciences
URI: http://www.lib.ncsu.edu/resolver/1840.16/217


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