In:
Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 105, No. D19 ( 2000-10-16), p. 24283-24304
Abstract:
In situ observations Of NO 2 , NO, NO y , ClONO 2 , OH, O 3 , aerosol surface area, spectrally resolved solar radiation, pressure and temperature obtained from the ER‐2 aircraft during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) experiments are used to examine the factors controlling the fast photochemistry connecting NO and NO 2 and the slower chemistry connecting NO x and HNO 3 . Our analysis uses “chemical coordinates” to examine gradients of the difference between a model and precisely calibrated measurements to provide a quantitative assessment of the accuracy of current photochemical models. The NO/NO 2 analysis suggests that reducing the activation energy for the NO+O 3 reaction by 1.7 kJ/mol will improve model representation of the temperature dependence of the NO/NO 2 ratio in the range 215–235 K. The NO x /HNO 3 analysis shows that systematic errors in the relative rate coefficients used to describe NO x loss by the reaction OH + NO 2 → HNO 3 and by the reaction set NO 2 + O 3 → NO 3 ; NO 2 + NO 3 → N 2 O 5 ; N 2 O 5 + H 2 O → 2HNO 3 are in error by +8.4% (+30/−45%) (OH+NO 2 too fast) in models using the Jet Propulsion Laboratory 1997 recommendations [DeMore et al., 1997]. Models that use recommendations for OH+NO 2 and OH+HNO 3 based on reanalysis of recent and past laboratory measurements are in error by 1.2% (+30/−45%) (OH+NO 2 too slow). The +30%/−45% error limit reflects systematic uncertainties, while the statistical uncertainty is 0.65%. This analysis also shows that the POLARIS observations only modestly constrain the relative rates of the major NO x production reactions HNO 3 + OH → H 2 O + NO 3 and HNO 3 + h ν → OH + NO 2 . Even under the assumption that all other aspects of the model are perfect, the POLARIS observations only constrain the rate coefficient for OH+HNO 3 to a range of 65% around the currently recommended value.
Type of Medium:
Online Resource
ISSN:
0148-0227
DOI:
10.1029/2000JD900290
Language:
English
Publisher:
American Geophysical Union (AGU)
Publication Date:
2000
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