from AGU Journal Highlights September 20, 2011
Arctic air may become cleaner as temperatures rise
The air in the Arctic is cleaner during summer than during winter. Previous studies have shown that for light-scattering pollutants, this seasonal cycle is due mainly to summer precipitation removing pollutants from the air during atmospheric transport from midlatitude industrial and agricultural sources.
With new measurements from Barrow, Alaska, and Alert, Nunavut, Canada, Garrett et al. extended previous research to show that light-absorbing aerosols such as black carbon are also efficiently removed by seasonal precipitation.
Precipitation removes these particles from the air most efficiently at high humidities and relatively warm temperatures, suggesting that as the Arctic gets warmer and wetter in the future, the air and snow might also become cleaner. If Arctic aerosols have a net warming effect, as is believed to be the case, precipitation removing these particles from the air would represent a negative climate feedback, mitigating anticipated Arctic warming.
GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L16805, 6 PP., 2011