Transport of photochemical ozone along the western Adriatic shore near a petrochemical plant

Summary During the warm months, the whole area surrounding Ravenna's petrochemical plant, which is about 5 km inshore of the northern Adriatic coast (Po Valley region), is subject to photochemical reactions producing high values of ozone concentration. The transport offshore of oxidants' precursors by the land breeze, photochemical reactions and subsequent transport inshore of oxidants by the sea breeze, may cause high concentrations of ozone along the coast up until the late evening. Similar phenomena have already been observed in other coastal regions. Classifying the ozone data into days with different circulations, the following can be seen: on days with W or NW circulation, a regular diurnal variation of ozone correlated with solar radiation is found; with winds from E or SE, the ozone variations are irregular and ozone concentrations can maintain high levels ((40÷70) p.p.b.) even during the nightime. This is a report of the results of several field measurements aimed at showing the ozone production and destruction processes, as well as its recirculation mechanisms under breeze conditions. Paper presented at the 1^o Congresso del Gruppo Nazionale per la Fisica dell'Atmosfera e dell'Oceano, June 19–22, 1984, Rome.