Measurements of the sum of HO 2 NO 2 and CH 3 O 2 NO 2 in the remote troposphere

• Main Authors: Murphy, J. G., Thornton, J. A., Wooldridge, P. J., Day, D. A., Rosen, R. S., Cantrell, C., Shetter, R. E., Lefer, B., Cohen, R. C.
• Other Authors: Lawrence Berkeley National Laboratory Berkeley (LBNL), National Center for Atmospheric Research Boulder (NCAR)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Tropospheric Ozone Production About the Spring Equinox
• Online Access: https://hal.science/hal-00301364; https://hal.science/hal-00301364/document; https://hal.science/hal-00301364/file/acpd-3-5689-2003.pdf

International audience The chemistry of peroxynitric acid (HO 2 NO 2 ) and methyl peroxynitrate (CH 3 O 2 NO 2 ) is predicted to be particularly important in the upper troposphere where temperatures are frequently low enough that these compounds do not rapidly decompose. At temperatures below 240 K, we calculate that about 20% of NO y in the mid and polar latitude upper troposphere is HO 2 NO 2 . Under these conditions, the reaction of OH with HO 2 NO 2 is estimated to account for as much as one third of the permanent loss of hydrogen radicals. During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign, we used thermal dissociation laser-induced fluorescence (TD-LIF) to measure the sum of peroxynitrates (SPNs equivanlent HO 2 NO 2 + CH 3 O 2 NO 2 + PAN + PPN + .), aboard the NCAR C-130 research aircraft. We infer the sum of HO 2 NO 2 and CH 3 O 2 NO 2 as the difference between SPN measurements and gas chromatographic measurements of the two major peroxy acyl nitrates, peroxy acetyl nitrate (PAN) and peroxy propionyl nitrate (PPN). Comparison with NO y and other nitrogen oxide measurements confirms the importance of HO 2 NO 2 and CH 3 O 2 NO 2 to the reactive nitrogen budget and shows that current thinking about the chemistry of these species is approximately correct. The temperature dependence of the inferred concentrations corroborates the contribution of overtone photolysis to the photochemistry of peroxynitric acid.