Open AccessThe coupling of ClONO 2 , ClO, and NO 2 in the lower stratosphere from in situ observations using the NASA ER‐2 aircraft
Author(s) -
Stimpfle R. M.,
Cohen R. C.,
Bonne G. P.,
Voss P. B.,
Perkins K. K.,
Koch L. C.,
Anderson J. G.,
Salawitch R. J.,
Lloyd S. A.,
Gao R. S.,
Del Negro L. A.,
Keim E. R.,
Bui T. P.
Publication year - 1999
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jd900288
Subject(s) - stratosphere , zenith , atmospheric sciences , photodissociation , ozone , arctic , analytical chemistry (journal) , chemistry , meteorology , physics , photochemistry , optics , environmental chemistry , geology , oceanography
The first in situ measurements of ClONO 2 in the lower stratosphere, acquired using the NASA ER‐2 aircraft during the Polar Ozone Loss in the Arctic Region in Summer (POLARIS) mission, are combined with simultaneous measurements of ClO, NO 2 , temperature, pressure, and the calculated photolysis rate coefficient (J ClONO2 ) to examine the balance between production and loss of ClONO 2 . The observations demonstrate that the ClONO 2 photochemical steady state approximation, [ClONO 2 ] PSS = k × [ClO] × [NO 2 ] / J ClONO2 , is in good agreement with the direct measurement, [ClONO 2 ] MEAS . For the bulk of the data (80%), where T>220 K and latitudes >45°N, [ClONO 2 ] PSS = 1.15±0.36 (1σ) × [ClONO 2 ] MEAS , while for T<220 K and latitudes <45°N the result is somewhat less at 1.01±0.30. The cause of the temperature and/or latitude trend is unidentified. These results are independent of solar zenith angle and air density, thus there is no evidence in support of a pressure‐dependent quantum yield for photodissociation of ClONO 2 at wavelengths >300 nm. These measurements confirm the mechanism by which active nitrogen (NO x = NO + NO 2 ) controls the abundance of active chlorine (Cl x = ClO + Cl) in the stratosphere.