Peroxy radical chemistry during FIELDVOC 1993 in Brittany, France

Peroxy radicals were measured using the technique of chemical amplification in two configurations during the FIELDVOC experiment during May and June, 1993 in Brittany, France. The two measurements showed good agreement during most of the periods when they overlapped. As observed at other sites, peroxy radicals can be responsible for significant daytime in situ ozone production. They can also be formed at night through NO3-radical reaction with various organic compounds, most notably dimethyl sulfide, other sulfur-containing compounds, as well as other organic compounds present in abundance at this coastal site. The hypotheses put forward to suggest that these reactions are important in the marine troposphere could not be tested fully due to instrumental limitations in the RO2 and NO3 measurements, but these measurements place strong constraints on the strength of these radical sources. The importance of possible heterogeneous loss of peroxy and nitrate radicals is addressed with the measurement and associated modeling efforts.