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Nitrogen Oxides

Nitrogen Oxides. The Berkeley TD-LIF Instrument/Comparisons Convection, NO 2 peak at 10km, Age of air, HO x chain termination (by NO x ) in the continental boundary layer. Tim Bertram Anne Perring Paul Wooldridge. LIF Detection of NO 2. PMT Sample

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Nitrogen Oxides

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  1. Nitrogen Oxides • The Berkeley TD-LIF Instrument/Comparisons • Convection, NO2 peak at 10km, Age of air, • HOx chain termination (by NOx) in the continental boundary layer

  2. Tim Bertram Anne Perring Paul Wooldridge

  3. LIF Detection of NO2 PMT Sample Using a supersonic expansion to cool NO2 to about 25K Multi-pass Cell ( 1 of 2 ) To Pump Nd3+:YAG 585 nm Tunable Dye Laser 532 nm Thornton et al. Anal. Chem. 72, 528, 2000 Cleary et al. Appl. Opt. 41(33), 6950, 2002

  4. SPNs, SANs, & HNO3 + heat  ROx + NO2 Thermal Dissociation-LIF Doug A. Day, et al, JGR., 107(D6), ‘02.

  5. (RONO2) (RO2NO2)

  6. Unheated inlet to cell 1 to cell 2 Heated inlets 200C - dissociation of ΣPNs to cell 2 350C - dissociation of ΣPNs and ΣANs to cell 1 580C - dissociation of ΣPNs, ΣANs andHNO3

  7. Convection/Age of Air

  8. Mid-Atlantic continental profile Assumes tropopause at 10km and BL well mixed and interpolated to the ground

  9. 0-D time dependent model: Noon injection, no dilution, 10km

  10. 11 August 2004 ALT>8km

  11. Lightning hits 10/11 August 2004 2day back trajectory

  12. 1-min merge data; Model fit to exponential

  13. Isoprene Nitrates

  14. Hydrocarbons (RO2) OH Sillman and Sampson JGR 1995

  15. Isoprene Oxidation H2CO yield is 0.6 O3 yield is 2(1-a) where a is kb/(ka+kb) + O2 NO2 kb + NO ka + NO (Alkyl nitrate) NO2 + + O2 + NO OH + NO2

  16. Observed contributions to RO2.production Distribution of NOy 7/20/2004 HNO3 (18%) NO2 (19%) ΣANs (31%) ΣPNs (32%) Ethane 4% *HNO3 data courtesy of Wennberg et al, CalTech Propane 9% Butane 6% Pentane 3% Alkenes 12% Isoprene 66% Hydrocarbon data provided by Blake et al, UC Irvine

  17. SANs and O3 RO2 + NO  RO + NO2 97% RO' + O2  R’O + HO2 HO2 + NO  OH + NO2 RO2 + NO  RONO2 3% 2 x 97 O3 : 3 SANs 65 O3 : SAN

  18. ANs v. O3 (under 1 km) 4 x 10 12 10 8 6 O3 (pptv) 4 O3 = 45 SANs + 35,275 2 r2 = 0.44 Implied branching ratio = 4.3% 0 0 500 1000 1500 SANs (pptv)

  19. 800 700 600 500 400 300 200 100 0 -100 -200 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 H2CO v. ANs (under 1 km) SANs (pptv) SANs = 0.067 H2CO - 40.6 r2 = 0.38 Implied branching ratio = 4.1% H2CO (pptv)

  20. HOx Chain Termination

  21. HOx- HOx NOx- HOx Chain Termination H2O2 + O2 HO2 + HO2 ROOH + O2 HO2 + RO2 H2O + O2 HO2 + OH M HNO3 NO2 + OH M RONO2 RO2 + NO

  22. 4 x 10 16 14 12 10 8 6 4 2 0 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 HNO3 + ANs v. NO2 + O3 (under 1 km) 75% HNO3 and 25% 3 SANs NO2 + O3 (pptv) O3 = 13.7 (HNO3+SANs) + 32,327 R2=0.77 HNO3 + ANs (pptv)

  23. Plans & Questions Describe distribution of age of air between 8 and 12 km. Understand how age affects other photochemical processes. What other short lived species (e.g. H2COare lofted by convection)? How well can we connect observations of atmospheric composition in the PBL to the observations at 8-12km? Will that provide a way to measure lightning NOx? Assess whether data does cleanly constrain isoprene nitrate yield. Characterize SAN/HNO3 roles in HOx chain termination. Where do the SANs go?

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