An analysis of fast photochemistry over high northern latitudes during spring and summer using in-situ observations from ARCTAS and TOPSE ...

• Main Authors: Olson, J. R., Crawford, J. H., Brune, W., Mao, J., Ren, X., Fried, A., Anderson, B., Apel, E., Beaver, M., Blake, D., Chen, G., Crounse, J., Dibb, J., Diskin, G., Hall, S. R., Huey, L. G., Knapp, D., Richter, D., Riemer, D., St. Clair, J., Ullmann, K., Walega, J., Weibring, P., Weinheimer, A., Wennberg, P., Wisthaler, A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Copernicus Publications 2012
• Subjects: Arctic
• Online Access: https://dx.doi.org/10.13016/m2eocz-vwpt; http://mdsoar.org/handle/11603/18924

Observations of chemical constituents and meteorological quantities obtained during the two Arctic phases of the airborne campaign ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) are analyzed using an observationally constrained steady state box model. Measurements of OH and HO₂ from the Penn State ATHOS instrument are compared to model predictions. Forty percent of OH measurements below 2 km are at the limit of detection during the spring phase (ARCTAS-A). While the median observed-to-calculated ratio is near one, both the scatter of observations and the model uncertainty for OH are at the magnitude of ambient values. During the summer phase (ARCTAS-B), model predictions of OH are biased low relative to observations and demonstrate a high sensitivity to the level of uncertainty in NO observations. Predictions of HO₂ using observed CH₂O and H₂O₂ as model constraints are up to a factor of two larger than observed. A temperature-dependent terminal loss rate of HO₂ to ...