OH and HO<sub>2</sub> chemistry in the North Atlantic free troposphere

B OH and HO<sub>2</sub> chemistry in the North Atlantic free troposphere

OH and HO₂ chemistry in the North Atlantic free troposphere

Brune, W.H., D. Tan, I.F. Faloona, L. Jaegle, D.J. Jacob, B.G. Heikes, J. Snow, Y. Kondo, R. Shetter, G.W. Sachse, B. Anderson, G.L. Gregory, S. Vay, H.B. Singh, R. Pueschel, G. Ferry, D.D. Davis, and D.R. Blake

Geophys. Res. Lett., 26, 3077-3080, 1999.

Abstract

Interactions between atmospheric hydrogen oxides and aircraft nitrogen oxides determine the impact of aircraft exhaust on atmospheric chemistry. To study these interactions, the Subsonic Assessment: Ozone and Nitrogen Oxide Experiment (SONEX) assembled the most complete measurement complement to date for studying HO_x (OH and HO₂) chemistry in the free troposphere. Observed and modeled HO_x agree on average to within experimental uncertainties, particularly for HO₂/OH, an indicator of the fast HO_x exchange chemistry. However, observed-to-modeled HO_x differences vary as a function of NO_x and solar zenith angle > 70^o. Some discrepancies appear to be removed by model adjustments to HO_x-NO_x chemistry, particularly by reducing HO₂NO₂ (PNA) formation and by including heterogeneous reactions on aerosols and cirrus clouds. These questions of HO_x-NO_x chemistry must be answered before issues of missing HO_x sources can be resolved.

OH and HO2 chemistry in the North Atlantic free troposphere

Abstract

OH and HO₂ chemistry in the North Atlantic free troposphere