Laboratory Experiments on Nitric Acid Uptake by a Meteoric Smoke Analogue

Amorphous olivine particles have been synthesised using the sol-gel technique to provide analogues of meteoric smoke particles. A Knudsen cell was used to measure an uptake coefficient of nitric acid on meteoric smoke of 3 × 4 x 10-3. Employing this parameter in an atmospheric model of smoke transport suggests that in the polar winter vortex, where meteoric smoke is concentrated (and photolysis is negligible) the lifetime of HNO3 with respect to heterogeneous removal is around 4 months, which is similar to the length of the polar winter. One uncertainty in this estimate is the size of the cosmic dust input to the atmosphere (assumed here to be 20 t d-1, one quarter of which ablates).