Measurements of N2O5, NO2, and O3 east of the San Francisco Bay

Contra Costa County, California during January 2004. Mixing ratios of N2O5, an intermediate compound in the atmosphere's nocturnal cleansing process, ranged up to 200 pmol/mol at night. The highest N2O5 concentrations were correlated with low O-3 and high NO2 concentrations. The calculated steady state lifetime for N2O5 ranged from 5 to 30 min. The total HNO3 produced by N2O5 hydrolysis over a 14 h night was comparable to ambient NO2 concentrations, and is estimated to be a factor of nine bigger than the HNO3 produced during the day.