Analysis of sea breezes characteristics in south-west Spain using observational data

Sea breezes are mesoscale meteorological phenomena driven by the thermal contrast between land and sea, which significantly affect local atmospheric circulation. These phenomena play a crucial role in regulating extreme temperatures, transporting atmospheric pollutants, as well as for wind energy resources. This study focuses on the Gulf of Cádiz, located in the southwest of   the Iberian Peninsula.

The main objective of our research is to use observational data to characterise the sea breeze system in this region, with a special focus on how the turbulent variables (turbulent kinetic energy (TKE), friction velocity (u*)) and the surface turbulent fluxes vary throughout the diurnal cycle under sea breeze conditions. This is especially interesting in the area of study since it is characterized by a mesotidal regime with sea-level oscillations of up to 4 meters. In this sense, turbulence data were obtained using a sonic anemometer installed at 10 m above sea level (asl) just on the coastline, in front of a surface that periodically changes its characteristics due to the tides. Besides, an IRGASON system was installed nearby on the top of a lighthouse, at 68 m asl, to investigate the fluxes and turbulent parameters at higher levels. The horizontal characterisation of the breeze system was obtained from observations of a network of weather stations strategically distributed along the coast. In addition, vertical atmospheric profiles before and during sea breeze events were analysed using radiosonde data to better understand the associated vertical structure and atmospheric dynamics.

The analysis covers events recorded during the summers of recent years, using an objective algorithm based on previous studies (Borne et al., 1988; Arrillaga et al., 2018; Román-Cascón et al., 2019) to accurately identify breeze events.

Preliminary results show variations in turbulent characteristics throughout the tidal cycle, highlighting the complex interaction between turbulent dynamics and coastal conditions during sea breeze events. This research contributes to improving the understanding of the complex breeze system in the study area and provides valuable data to evaluate numerical models and improve atmospheric boundary layer parameterisations.