Visible and near-ultraviolet spectroscopy at McMurdo Station, Antarctica 10: Reductions of stratospheric NO{sub 2} due to Pinatubo aerosols
- NOAA, Boulder, CO (United States); and others
Visible absorption spectroscopy was employed for stratospheric measurements at McMurdo Station, Antarctica, during the summer and fall seasons in 1990, 1991, 1992, and 1993. Observed column amounts of NO{sub 2} were as much as 50% smaller in 1992 and 1993 than in 1990 and 1991. The measured decreases in NO{sub 2} are believed to be due to the hydrolysis of N{sub 2}O{sub 5} on the enhanced volcanic aerosols injected by the massive eruption of Mount Pinatubo in mid-1991. Such decreases in NO{sub 2} are broadly consistent with observations at other latitudes and with model calculations. However, substantially reduced NO{sub 2} was also observed during the polar day period in summer under conditions of continuous local solar illumination. The formation of the key N{sub 2}O{sub 5} intermediate and reduction of NO{sub 2} at this time of year probably occurs via two mechanisms: (1) excursions of air parcels to lower latitudes where nighttime chemistry can produce N{sub 2}O{sub 5} and (2) conversion of a small fraction of the NO{sub 3} formed during the day to N{sub 2}O{sub 5}. Model calculations show that the latter mechanism can be important in spite of the fast daytime photolysis of NO{sub 3}. 27 refs., 10 figs., 1 tab.
- OSTI ID:
- 136158
- Journal Information:
- Journal of Geophysical Research, Vol. 99, Issue D2; Other Information: PBD: 20 Feb 1994
- Country of Publication:
- United States
- Language:
- English
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