Observations of large reductions in the NO/NOyratio near the mid-latitude tropopause and the role of heterogeneous chemistry

Autor: Eric J. Hintsa, James C. Wilson, Michael H. Proffitt, K. K. Kelly, James E. Dye, Paul O. Wennberg, Darrel Baumgardner, L. A. Del Negro, R. S. Gao, Stephan R. Kawa, Ronald C. Cohen, James R. Podolske, Ross J. Salawitch, R. M. Stimpfle, K. R. Chan, E. L. Woodbridge, David W. Fahey, Max Loewenstein, E. R. Keim, Haflidi Jonsson
Rok vydání: 1996
Předmět:
Zdroj: Geophysical Research Letters. 23:3223-3226
ISSN: 0094-8276
DOI: 10.1029/96gl02593
Popis: During the 1993 NASA Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE), anomalously low nitric oxide (NO) was found in a distinct sunlit layer located above the mid-latitude tropopause. The presence of a significant amount of reactive nitrogen (NO_y) in the layer implies the systematic removal of NO, which is without precedent in stratospheric in situ observations. Large increases in measured chlorine monoxide (ClO) and the hydroperoxyl radical (HO_2) also were observed in the layer. Heterogeneous reaction rate constants of chlorine nitrate (ClONO_2) with hydrogen chloride (HCl) and H_2O to form nitric acid (HNO_3) on sulfate aerosol are enhanced in the NO removal layer by local increases in H_2O and aerosol surface area. The associated conversion of NO_x (= NO + NO_2) to HNO_3 is the most likely cause of the observed low NO and NO_x/NO_y values and high ClO values.
Databáze: OpenAIRE