MULTIPHASE CHEMISTRY OF NO3 IN THE REMOTE TROPOSPHERE

The effect ofNO(3) uptake at night into marine aerosol and cloud dropl ets on (1) sulfur oxidation, (2) NO3 ambient concentrations, and (3) N O3 atmospheric lifetime is examined using a simple chemical kinetics m odel. It is shown that the atmospheric lifetime toward multiphase remo val of NO3 is < 10 min in presence of cloud droplets. We also show tha t at low mixing ratios of H2O2 (<150 pmol/mol), NO3 can enhance sulfur oxidation in clouds via a catalytic cycle with a chain length of simi lar to 8. Finally, in presence of sea-salt aerosol, the uptake of NO, leads to low ambient concentrations of NO3, efficient S(IV) oxidation, and possibly, to release of halogens from the aerosol. The results of this study imply that the multiphase reaction of NO3 may be important in the remote marine boundary layer.