CONTINUOUS AIRBORNE MEASUREMENTS OF GASEOUS FORMIC AND ACETIC-ACIDS OVER THE WESTERN NORTH-ATLANTIC

A tandem mass spectrometer modified for aircraft applications was used to measure gas-phase formic and acetic acid mixing ratios over the we stern North Atlantic during late summer 1992. The sensitive, specific, and essentially real-time measurements provided by the mass spectrome ter allow a true spatial evaluation of these compounds in the study ar ea. Formic and acetic acid mixing ratios showed substantial vertical v ariation, varying by factors of up to 13 and 6, respectively, within 2 -km profiles extending from the boundary layer into the free troposphe re. Substantial horizontal variation was also observed at constant alt itudes within both the boundary layer and free troposphere. Mixing rat ios of the two acids were correlated (r2 > 0.70) throughout the study region.