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Changes in CH 4 and CO growth rates after the eruption of Mt. Pinatubo and their link with changes in tropical tropospheric UV flux
Author(s) -
Dlugokencky E. J.,
Dutton E. G.,
Novelli P. C.,
Tans P. P.,
Masarie K. A.,
Lantz K. O.,
Madronich S.
Publication year - 1996
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 - 10.1029/96gl02638
Subject(s) - stratosphere , atmospheric sciences , flux (metallurgy) , radiative transfer , troposphere , trace gas , environmental science , vulcanian eruption , latitude , sulfate aerosol , absorption (acoustics) , sulfate , volcano , geology , chemistry , physics , organic chemistry , quantum mechanics , seismology , acoustics , geodesy
Trace gas measurements from air samples collected weekly at a globally distributed network of sampling sites revealed sharp increases in the growth rates of CH 4 and CO in the tropics and high southern latitudes immediately following the eruption of Mt. Pinatubo on June 15, 1991. The eruption emitted ∼20 Mt SO 2 into the lower stratosphere. Calculations made with a radiative transfer model show that UV actinic flux in the wavelength region 290–330 nm was attenuated by ∼12% immediately after the eruption due to direct absorption by SO 2 , and that it was perturbed for up to 1 year after the eruption due to scattering by sulfate aerosols. We suggest that the decreased UV flux decreased the steady‐state [OH] and led to the observed anomalously large growth rates for CH 4 and CO during late‐1991 and early‐1992.