The objective of this project is to measure several important products of atmospheric photolysis including the hydroxyl radical, and gas phase sulfuric and methanesulfonic acids using a mass spectrometric technique. In addition , the instrument used to perform these measurements will be modified to make possible shipboard and aircraft studies. A recent informal intercomparison between the mass spectrometric measurement technique and a NOAA long path laser absorption technique resulted in similar concentrations of OH being measured by both instruments. The measured hydroxyl radical concentrations were however, consistently well below model predictions. In order to investigate these discrepancies these scientists will participate in an additional hydroxyl radical intercompaion and photochemistry experiment in Colorado during the summer of 1993. A second study to isolate possible effects of vegetation and other near-ground loss mechanisms on hydroxyl radical concentration will also be undertaken. Modifications to the present system would also be undertaken to make possible measurements on a mobile platform for future studies.
