Photochemistry in the arctic free troposphere: NO_x budget and the role of odd nitrogen reservoir recycling

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• 作者：Stroud ; Craig ; Madronich ; Sasha ; Atlas ; Elliot ; Ridley ; Brian ; Flocke ; Frank ; Weinheimer ; Andy ; et. al.
• 关键词：Atmospheric chemistry ; Arctic troposphere ; TOPSE ; Peroxynitric acid ; Acetaldehyde
• 刊名：Atmospheric Environment
• 出版年：2003
• 出版时间：August, 2003
• 年：2003
• 卷：37
• 期：24
• 页码：3351-3364
• 全文大小：703 K

文摘

The budget of nitrogen oxides (NO_x) in the arctic free troposphere is calculated with a constrained photochemical box model using aircraft observations from the Tropospheric O₃ Production about the Spring Equinox (TOPSE) campaign between February and May. Peroxyacetic nitric anhydride (PAN) was observed to be the dominant odd nitrogen species (NO_y) in the arctic free troposphere and showed a pronounced seasonal increase in mixing ratio. When constrained to observed acetaldehyde (CH₃CHO) mixing ratios, the box model calculates unrealistically large net NO_x losses due to PAN formation (62pptv/day for May, 1–3km). Thus, given our current understanding of atmospheric chemistry, these results cast doubt on the robustness of the CH₃CHO observations during TOPSE. When CH₃CHO was calculated to steady state in the box model, the net NO_x loss to PAN was of comparable magnitude to the net NO_x loss to HNO₃ (NO₂ reaction with OH) for spring conditions. During the winter, net NO_x loss due to N₂O₅ hydrolysis dominates other NO_x loss processes and is near saturation with respect to further increases in aerosol surface area concentration. NO_x loss due to N₂O₅ hydrolysis is sensitive to latitude and month due to changes in diurnal photolysis (sharp day–night transitions in winter to continuous sun in spring for the arctic). Near NO_x sources, HNO₄ is a net sink for NO_x; however, for more aged air masses HNO₄ is a net source for NO_x, largely countering the NO_x loss to PAN, N₂O₅ and HNO_3. Overall, HNO₄ chemistry impacts the timing of NO_x decay and O₃ production; however, the cumulative impact on O₃ and NO_x mixing ratios after a 20-day trajectory is minimal.