A numerical study of the effect of sea breeze circulations on photochemical pollution over a highly industrialized peninsula

Numerical simulations compared with measurements are used to investigate the effect of sea breeze circulation on the ozone accumulation over a highly industrialized peninsula in southern Italy, where high levels of ozone concentration are often registered. A frequent meteorological phenomenon in this region during weak summer synoptic conditions is the development of complex sea breeze systems from the coastlines, with convergence areas within the peninsula. A case study characterized by strong winds alternating with sea breeze circulations was selected. The simulations show that during weak synoptic conditions, sea breezes transport ozone and its precursors over land from the sea, as well as from the coastlines where the largest industrialized districts are localized. The overlapping breezes lead to ozone accumulation in the area where sea breeze convergence occurs. This may explain the high values of ozone registered close to the sea breeze convergence lines. The comparison between predictions and experimental data indicates that the numerical system successfully reproduces both weather and ground level ozone concentration in different meteorological conditions, resulting in a fundamental tool for both scientific comprehension of the evolution of air contaminants and interpretation of the monitoring data.