Aerosol-mediated partitioning of stratospheric Cly and NOy at temperatures above 200 K

Rates of aerosol-mediated reactions involving inorganic halogen species are small but non-negligible for moderate aerosol abundances at temperatures of 200–210 K. We have used a photochemical model to demonstrate that at these temperatures such reactions provide a significant sink for HCl. Gas-phase production rates are slower for HCl than for ClNO₃. The net result is preferential partitioning of Cl_y into [ClNO₃] to compensate for the accelerated loss of [HCl]. Under such conditions, [HNO₃] decreases in response to enhanced partitioning of NO_y into [ClNO₃]. The results indicate a high sensitivity and synergistic response of HCl, ClNO₃, and HNO₃ distributions to aerosol content and temperature.