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Browsing Centre for Atmospheric Chemistry by Author "Albritton, D.L."
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Item Open Access Aircraft Measurements of NOx Over the Eastern Pacific and Continental United States and Implications for Ozone Production(AGU, 1990) Carroll, M.A.; Hastie, D.R.; Ridley, B.A.; Rodgers, M.O.; Torres, A.L.; Davis, D.D.; Bradshaw, J.D.; Sandholm, S.T.; Schiff, H.I.; Karecki, D.R.; Harris, G.W.; Mackay, G.I.; Gregory, G.L.; Condon, E.P.; Trainer, M.; Hubler, G.; Montzka, D.D.; Madronich, S.; Albritton, D.L.; Singh, H.B.; Beck, S.M.; Shipham, M.C.; Bachmeier, A.S.Measurements of NO, NO2, O3, and CO are presented from 13 aircraft flights made over the eastern Pacific Ocean and the continental United States in August and September 1986 during the NASA GTE/CITE 2 program. Measurements of NO by three different groups (two different techniques) and of NO2 by three different groups (three different techniques) are presented and examined along with calculated NO x (NO + NO2) for correlations with O3, CO, and dew-point temperature (DPT) primarily as a function of air mass category. Median values of NO and NO2 in the marine boundary layer were 4.0 and 10.4 pptv, respectively, and 12.4 and 18.0 pptv in the marine free troposphere. In the continental boundary layer, median values of NO and NO2 were 34.5 and 75.0 pptv, respectively, and 13.0 and 36.0 pptv at altitudes above 3 km in air masses having continental influence. In the maritime NO x data set a negative correlation is often observed between NO x and DPT, while positive correlations were typically observed between NO x and O3 and between NO x and CO. As expected, then, negative correlations were often observed between O3 and DPT and between CO and DPT, along with positive correlations between CO and O3. In the continental data set, positive correlations were typically observed between NO x and DPT, O3, and CO. Additionally, the various air masses were examined with respect to regions of net ozone production or net ozone destruction. In all but one case in the marine boundary layer, model calculations indicate that there is significant ozone destruction. In the continental boundary layer, however, calculations indicate significant ozone production. In the middle free troposphere at 5 ± 1 km, the in situ ozone formation was most often nearly in balance with ozone destruction.Item Open Access Ratios of Peroxyacetyl Nitrate to Active Nitrogen Observed During Aircraft Flights Over the Eastern Pacific Ocean and Continental United States(AGU, 1990) Ridley, B.A.; Shetter, J.D.; Grandrud, B.W.; Salas, L.J.; Singh, H.B.; Carroll, M.A.; Hubler, G.; Albritton, D.L.; Hastie, D.R.; Schiff, H.I.; Mackay, G.I.; Karecki, D.R.; Davis, D.D.; Bradshaw, J.D.; Rodgers, M.O.; Sandholm, S.T.; Torres, A.L.; Condon, E.P.; Gregory, G.L.; Beck, S.M.During August and September 1986, 11 aircraft flights were made over the eastern Pacific Ocean and continental United States. The suite of observations included simultaneous measurements of peroxyacetyl nitrate (PAN) and active nitrogen (NOx=NO+NO2). At altitudes of 4.5–6.1 km in the middle free troposphere, PAN was usually 5–6 times NOx in maritime air masses and 2–4 times NOx in continental air masses. In air masses of tropical origin, or in the marine boundary layer, both PAN and NOx were typically less than 20–30 parts per trillion by volume, and the PAN to NOx ratio was less than one. The observations show that PAN can be a major component of the odd nitrogen budget in the middle free troposphere and strongly reinforce earlier views that the abundance is mainly governed by long-range transport processes including formation during transport and continental boundary layer to free tropospheric exchange of PAN and its precursors. Unlike reservoir HNO3, PAN can be transformed to active nitrogen and peroxy radicals by a variety of physical atmospheric processes that lead to air mass warming. Since NOx plays a critical role in determining photochemical O3 production, which in turn determines the oxidative power of the atmosphere, the observed large ratios of reservoir PAN to active NOx imply an important photochemical and dynamical role for PAN in the eastern Pacific remote free troposphere.