High nocturnal ozone transport in greater Ravenna

摘要

Abstract: Continuous monitoring of Raven's seaboard since 1978 has evinced high nocturnal ozone concetrations. The present study of the averaged ozone values at three monitoring stations in the summers of 1993 and 1994, when there were no significant variations in precursor emission sources or in the usual weather conditions, shows nocturnal minima generally occurring between 3 o'clock and 7 o'clock am local time in a 20-30 $mu@g/m$+3$/ range. Nocturnal values above the normal range ($APGR 70 $mu@g/m$+3$/) has a 6% frequency and, when compared to weather conditions, occured simultaneously at all sites (spaced 5-10 km apart) and coincided with the passing of a front or a low-pressure situation. !5