Quantifying the thermodynamic impacts on the atmospheric boundary layer due to the sea breeze in the coastal Houston region
Francesca Lappin is student at the OU School of Meteorology in the PhD degree program. She works as a research assistant in the BLISS group under Dr. Klein. Prior to coming to OU, she earned a BS in Meteorology from the Florida State University and later an MS at OU.
Abstract
The evolution of the atmospheric boundary layer (ABL) is unique in coastal regions because there are kinematic and thermodynamic influences from both the continental and marine boundary layers. The heterogeneous terrain leads to distinctly different vertical structures and stability with a transient interface over a short horizontal distance. Sea breeze circulations (SBC) act to equilibrate the land-sea temperature gradient through advecting marine air onshore. The structure of the SBC is sensitive to prevailing conditions and heterogeneous in nature. Since observations are often sparse along the coast, a majority of research on the characteristics and implications of the SBC comes from numerical models. The TRacking Aerosol Convection Interactions ExpeRiment (TRACER) field campaign collected a wealth of data on boundary layer evolution, convective lifecycle processes, and aerosol transport. The project utilized a variety of platforms, but here we will focus on the observations from uncrewed aircraft systems (UAS). Vertical profiles, up to 609 m, of temperature, humidity, and winds collected with the OU CopterSonde UAS during four intensive observation periods from June to September in the coastal region of Houston are analyzed. Using the high temporal resolution UAS data, we are able to resolve the thermodynamic evolution and interaction with the pre-existing convective boundary layer. Results show that there is large variability between observed sea breezes and their impacts on the thermodynamic state. The prevailing wind, proximity to Galveston Bay, and time of day all play a role in how impactful the sea breeze is in altering the temperature and humidity levels. Moreover, the residence time of these changes is variable, and in some cases, the ABL rebounds to its previous well-mixed state after a few hours. In quantifying the spectrum of sea breeze impacts, low-level stability is used to contextualize its role in convection initiation and evolution. Sea breeze-initiated convection is associated with an increase in equivalent potential temperature prior to and throughout sea breeze passage.
Presentation
