HETEROGENEOUS REACTION PROBABILITIES, SOLUBILITIES, AND THE PHYSICAL STATE OF COLD VOLCANIC AEROSOLS

On 19 January 1992, heterogeneous loss of HNO3, ClNO3, and HCl was obs erved in part of the Mount Pinatubo volcanic cloud that had cooled as a result of forced ascent. Portions of the volcanic cloud froze near 1 91 kelvin. The reaction probability of ClNO3 and the solubility of HNO 3 were close to laboratory measurements on liquid sulfuric acid. The m agnitude of the observed loss of HCl suggests that it underwent a hete rogeneous reaction. Such reactions could lead to substantial loss of H Cl on background sulfuric acid particles and so be important for polar ozone loss.