The diurnal variation of hydrogen, nitrogen, and chlorine radicals: Implications for the heterogeneous production of HNO2 Academic Article uri icon


  • In situ measurements of hydrogen, nitrogen, and chlorine radicals obtained through sunrise and sunset in the lower stratosphere during SPADE are compared to results from a photochemical model constrained by observed concentrations of radical precursors and environmental conditions. Models allowing for heterogeneous hydrolysis of N 2 O 5 on sulfate aerosols agree with measured concentrations of NO, NO 2 , and ClO throughout the day, but fail to account for high concentrations of OH and HO 2 observed near sunrise and sunset. The morning burst of [OH] and [HO 2 ] coincides with the rise of [NO] from photolysis of NO 2 , suggesting a new source of HO x that photolyzes in the near UV (350 to 400 nm) spectral region. A model that allows for the heterogeneous production of HNO 2 results in an excellent simulation of the diurnal variations of [OH] and [HO 2 ]. Copyright 1994 by the American Geophysical Union.

published proceedings

  • Geophysical Research Letters

author list (cited authors)

  • Salawitch, R. J., Wofsy, S. C., Wennberg, P. O., Cohen, R. C., Anderson, J. G., Fahey, D. W., ... Bowen, S. W.

publication date

  • January 1, 1994 11:11 AM