Halogen ions and NO+ in the mass spectra of aerosols in the upper troposphere and lower stratosphere

Mass spectra of individual aerosol particles were acquired at altitudes up to 19 km during the WE-57 Aerosol Mission. Fluorine and chlorine were more abundant in tropospheric aerosols than in stratospheric aerosols. Chlorine in tropospheric aerosols was often associated with organics, soot, and mine ral dust. Small amounts of perchlorate were observed in stratospheric sulfa te aerosols, but aerosols do not represent a significant sink for total flu orine or chlorine in the lower stratosphere. Bromine was most common in aer osols just above the tropopause. where it may represent a significant fract ion of inorganic Br. Both bromine and iodine were highly correlated with or ganics and probably were present in particles with HE. The OH- and NO+ peak areas increased at temperatures below 195 K, providing evidence for the up take of H2O and HNO3 by aerosols near a cold tropopause. There was evidence for uptake of chlorine but not the other halogens below 190 K.