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Cosmogenic 35 S: A unique tracer to Antarctic atmospheric chemistry and the polar vortex
Author(s) -
Priyadarshi Antra,
Dominguez Gerardo,
Savarino Joel,
Thiemens Mark
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl047469
Subject(s) - troposphere , stratosphere , atmospheric sciences , aerosol , atmosphere (unit) , polar vortex , radiogenic nuclide , atmospheric chemistry , environmental science , chemistry , geology , isotope , ozone , meteorology , physics , nuclear physics , organic chemistry
The cosmogenic radionuclide 35 S (half life ∼87 d) exists in both 35 SO 2 gas and 35 SO 4 2− aerosol phase in the atmosphere. Cosmogenic 35 S fulfils a unique niche in that it has an ideal half‐life for use as a tracer of atmospheric processes, possesses a gas phase precursor and undergoes gas to particle conversion, providing a chronometer that complements other measurements of radiogenic isotopes of different half lives and chemical properties. Based on radiogenic 35 S measurements and concomitant model calculations, we demonstrate that 35 S is a unique tracer to understand stratospheric‐tropospheric air mass transport dynamics and the atmospheric oxidation capacity on a short time scale. Reported are the first measurements of 35 S contained in SO 4 2− aerosols (bulk and size aggregated) at Antarctica. 35 SO 4 2− concentrations at Dome C and Dumont D'Urville exhibit summer maxima and winter minima with a secondary winter peak. Higher oxidative capacity of the atmosphere and long range transport of mid latitude air increases 35 SO 4 2− activity in summer whereas a lack of air mass mixing coupled with low oxidant concentration in winter significantly decreases 35 SO 4 2− activity. A 3% contribution from stratospheric 35 SO 4 2− into the free troposphere during stratosphere‐troposphere air mass mixing accounts for the secondary winter 35 SO 4 2− peak. In the future, this work will be extended to 35 S activity measurements of both gas and aerosol phases to further understand gas to particle conversion, vortex dynamics and trace polar stratospheric cloud sedimentation frequency.