Publication Date:
2017-07-14
Description:
A meteoric sulfur input function and a sulfur ion chemistry scheme have been incorporated into a chemistry-climate model, in order to study the speciation of sulfur between the stratosphere and the thermosphere (~20 – 120 km), and the impact of the sulfur input from ablation of cosmic dust. The simulations have been compared to rocket observations of SO + between 85 and 110 km, MIPAS observations of SO 2 between 20 and 45 km, and stratospheric balloon-borne measurements of H 2 SO 4 vapor and sulfate aerosol. These observations constrain the present day global flux of meteoric sulfur to ≤ 1.0 t S d -1 , i.e. 2 orders of magnitude smaller than the flux of S into the stratosphere from OCS photo-oxidation and explosive volcanic SO 2 injection. However, the meteoric sulfur flux is strongly focused into the polar vortices by the meridional circulation, and therefore the contribution of SO 2 of meteoric origin to the polar upper stratosphere during winter is substantial (~ 30% at 50 km for a flux of 1.0 t S d -1 ). The Antarctic spring sulfate aerosol layer is found to be very sensitive to a moderate increase of the input rate of meteoric sulfur, showing a factor of 2 enhancement in total sulfate aerosol number density at 30 km for an input of 3.0 t S d -1 . The input rate estimate of 1.0 t S d -1 suggests an enrichment of sodium relative to sulfur of 2.7 ± 1.5 and is consistent with a total cosmic dust input rate of 44 t d -1 .
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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