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Near IR photolysis of HO 2 NO 2 : Implications for HO x
Author(s) -
Salawitch Ross J.,
Wennberg Paul O.,
Toon Geoffrey C.,
Sen Bhaswar,
Blavier JeanFrancois
Publication year - 2002
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 - 10.1029/2002gl015006
Subject(s) - photodissociation , stratosphere , troposphere , atmospheric sciences , physics , latitude , wavelength , infrared , astrophysics , atomic physics , chemistry , photochemistry , optics , astronomy
We report observations and calculations of peroxynitric acid, HO 2 NO 2 , in the stratosphere and upper troposphere. The simulations show that photolysis of HO 2 NO 2 via excitation of purely vibrational modes at wavelengths longward of 760 nm (the near IR) can dominate loss of this species. Consideration of this photolytic pathway reduces calculated HO 2 NO 2 , resolving a large discrepancy between standard model calculations and observations of HO 2 NO 2 at high‐latitude spring. The lower calculated abundance of HO 2 NO 2 reduces the efficiency of the OH + HO 2 NO 2 sink of HO x . Consideration of this process leads to large increases in calculated HO x (20 to 60%) for high‐latitude spring and better agreement with observed stratospheric abundances of HO x . Near IR photolysis of HO 2 NO 2 alters the coupling between NO x and HO x in stratospheric and upper tropospheric photochemical models.