Detection and analysis of sea breeze and sea breeze enhanced rainfall: a study of the Florida and Delmarva Peninsulas

Veron, Dana E.The sea breeze circulation is a local phenomenon that can greatly impact the climate of coastal regions. Especially during the warm season, sea breezes influence near surface wind direction and magnitude, temperature, and alter, or even enhance, precipitation patterns. The location and timing of the sea breeze circulation affects wind and water resources, air pollution transport, and tourism. The leading edge of the circulation, or sea breeze front, is associated with enhanced uplift due to warm air buoyancy. Under certain environmental conditions, this uplift can lead to convective activity, greatly influencing summertime precipitation in coastal areas. ☐ The purpose of this thesis, which consists of an introduction, two papers, a conclusion and an appendix, is to investigate the sea breeze circulation, specifically as it affects summertime precipitation in two coastal regions: Florida and Delaware. A state-of-the-art radar detection algorithm is introduced and employed in the first paper to study ten years (2009-2018) of summer (JJA) days in these two regions. We evaluate the characteristics of strong sea breeze fronts that are most likely to affect precipitation intensity and coverage. Analysis of the Dover, DE and Melbourne, FL study regions show that sea breezes associated with intense precipitation develop greater vertical extent closer to the coastline, and penetrate further inland compared to sea breeze days with no precipitation. ☐ In the second paper, we take a regional approach to study the impact of the summertime sea breeze on precipitation patterns on the South Florida Peninsula. Station data are employed to characterize days based on sea breeze occurrence. Then, precipitation frequency and amount on these days are analyzed and compared. Finally, we investigate environmental conditions, such as synoptic wind flow and coastal surface water temperatures, to better understand the environment within which the sea breeze develops and influences local weather, particularly precipitation. Results show that sea breeze significantly increases precipitation over Florida’s agricultural lands where summertime precipitation is needed for crop growth, especially on days with sea breeze occurrence along both the east and west coasts of the peninsula. Synoptic flow direction and magnitude influence sea breeze occurrence, in addition to the location and probability of precipitation in the study region. Further analysis to understand the role of surface water temperatures on sea breeze occurrence, and thus precipitation, especially along the eastern coast where the Gulf Stream affects near land water temperatures is recommended. ☐ Results presented in this thesis suggest that environmental conditions affect sea breeze characteristics and their ability to enhance or alter precipitation in coastal regions. The novel sea breeze detection algorithm presented here can be employed to study sea breeze circulations in any region where coastal radar data are available. Further, this study informs stakeholders interested in water resource management as to the physical mechanisms that influence summertime precipitation in these two study regions. Improved understanding of the summertime precipitation can lead to better economic decision making by farmers and water managers and enhanced preparation for a changing climate.University of Delaware, Department of GeographyM.S