1. Two puzzles of atmospheric chemistry over the Southeast US Jingqiu Mao (AOS/GFDL), Larry Horowitz (GFDL), Vaishali Naik (GFDL), Fabien Paulot (Harvard), Paul Ginoux(GFDL), Meiyun Lin (GFDL), Arlene Fiore (Columbia U) and the SENEX science team Funding from NOAA CPO

2. What is so unique for Southeast US? (Millet et al., 2008, JGR) (Martin et al., 2008, AE) Surface NO x is mainly produced from anthropogenic activities HCHO is mainly produced from biogenic emissions (isoprene in particular) Anthropogenic + Natural

3. Volatile organic compounds (VOCs) in the atmosphere: carbon oxidation chain VOCRO 2 NO 2 O3O3 organic peroxy radicals NO h carbonyls R’O 2 h OH + products organic aerosol ROOH organic peroxides OH HO 2 OH, h OH products EARTH SURFACE biosphere combustion industry deposition Increasing functionality & cleavage sources of organic aerosol sources/sinks of oxidants (ozone, OH) OVOCs Importance of NO x

4. Global Budget of Organic Aerosols fuel/industry open fires OH, O 3,NO 3 SOGSOA POA K vegetation fuel/industry open fires 700 isoprene terpenes oxygenates… 30 alkenes aromatics oxygenates… VOC EMISSIONPRIMARY EMISSION VOC 50 20100 20 Global sources in Tg C y -1 Two-product SOA ≡ secondary organic aerosol POA ≡ primary organic aerosol Current AM3 treats SOA production as yield of terpene emissions. Aqueous reactions ? ? Uptake on cloud droplets or aerosols

5. Puzzle 1: Overestimate of ozone

6. Summertime ozone over eastern US is a problem for most models (Fiore et al., 2009, JGR) Multimodel mean Obs from CASTNET surface sites Northeast US Southeast US Multimodel mean Obs from CASTNET surface sites Standard AM3 (Naik et al., 2013, JGR, in press)

7. Similar bias was found for the maximum daily 8-hour average ozone comparison. Overestimate of ozone is likely a chemistry problem Previous models with assimilated meteorology field (CTM) show similar overestimate. Models with higher resolution also show similar overestimate. Fiore et al. (2005) attributed this bias to the treatment of isoprene chemistry in the model. (Rasmussen et al., 2012, AE)

8. Puzzle 2 : Aerosols and regional cooling

9. Temperature trend over past century (Portmann et al., 2009, PNAS) 1950-2006 for May-June (Unit: K/Decade) (Leibensperger et al., 2012, ACP) This temperature trend cannot be explained by the change in precipitation or dynamic patterns (El Niňo, NAO) (Portmann et al., 2009). 1930-1990 change in Annual Mean Surface Temperature

10. The cooling can be partially due to secondary organic aerosols (Goldstein et al., PNAS, 2009) MISR aerosol optical thickness (diff. between JJA and DJF) MODIS aerosol optical thickness (diff. between JJA and DJF) (Ford et al., 2013, ACPD) Current hypothesis is that large amount of organic aerosols are produced above the surface layer.

11. Similar problem was found in GFDL models (Courtesy of Paul Ginoux and Ilissa Ocko) Optical properties from aircraft data (left) and the model (right) over Oklahoma, US Model cannot reproduce high loading of aerosols above the surface layer! CM 2.1 CM 3

12. Geophysical Fluid Dynamics Laboratory Surface Air Temperature OBS (GISS) K Stronger cooling at northern mid-latitudes in CM3, 3x less warming globally  examine forcings CM2.1 CM3 Years (1961-2000) minus (1881-1920) (Courtesy of Larry Horowitz)

13. Underestimate of organic aerosol is also a chemistry problem (Ford et al., 2013, ACPD) Current models cannot reproduce such amount of aerosols above the surface layer. This cannot be explained by PBL height, SO 2 emissions.

14. New development of chemistry in AM3: (1) heterogeneous chemistry

15. dust SO 4 BC OC Standard AM3 Updated AM3 N 2 O 5, HO 2 SO 4 Sea Salt N 2 O 5, HO 2, NO 3, NO 2 A new framework for heterogeneous chemistry RH(%)0507080909599 SO41.01.41.51.61.81.92.2 OC1.01.21.41.51.61.82.2 BC1.0 1.21.41.51.9 Sea salt 1.01.61.82.02.42.94.8 ReactionsUptake coefficient (γ) HO 2 → products1.0 N 2 O 5 → 2.0 HNO 3 0.1 NO 3 → 1.0 HNO 3 0.1 NO 2 → 0.5 HNO 3 0.0001 Hygroscopic growth factor (Mao et al., 2013a, ACP; 2013b, GRL)

16. Impact of heterogeneous chemistry (AM3 C48 2001-2005) (Mao et al., 2013a, ACP; 2013b, GRL) Simulation (het chem on) – Simulation (het chem off)

17. Improvement on CO at 500 hPa AM3 with het chem off MOPITT AM3 with het chem on MOPITT (2000-2004) AM3(2001-2005) Improvement on OH ratio (NH/SH) obs (Naik et al., 2013, JGR, in press)

18. The impact of biomass burning emissions on global OH/ozone: Implications for radiative forcing IPCC AR4 only estimates the direct forcing from biomass burning aerosols (+0.03 ±0.12 W m -2 )

19. Aerosol uptake has large impact on ozone production efficiency ΔO 3 / ΔCO is a measure of ozone production efficiency. Observations

20. Sensitivity of tropospheric oxidants to biomass burning emissions Global OH decreases with larger bb emissions. Global ozone increases with larger bb emissions.

21. (Mao et al., 2013b, GRL) Nonlinearity of total radiative forcing on biomass burning strength CH 4 -induced O 3 and H 2 O Steady state CH 4 Chemical indirect forcing from CH 4 and CH 4 -induced changes in O 3 and stratospheric H 2 O, is comparable to the cooling from biomass burning aerosols with direct and indirect effect taken into account. How about chemical indirect forcing from anthropogenic emissions?

22. New development of chemistry in AM3: (2) a new isoprene chemistry scheme

23. A new isoprene oxidation mechanism for global models (Mao et al., submitted to JGR) OH recycling from isoprene oxidation has been a hot topic in atmospheric chemistry community in last 5 years!

24. Was OH really that high over SE US during ICARTT? (Ren et al., 2008, JGR) OH measured by traditional method during ICARTT 2004 (Mao et al., 2012, ACP) Part of OH signal could be due to interference, probably from biogenic VOC oxidation products! A new method of measuring OH was deployed in Blodgett Forest

25. First generation of isoprene nitrates degraded to second generation nitrates! Second generation isoprene nitrates (C3-C4) First generation isoprene nitrates (C5) C5 alkyl nitrate is short-lived due to oxidation by OH and ozone, with photochemical lifetime of 2-3 hrs. (Paulot et al., 2009a,b)

26. NO y budget in eastern U.S. boundary layer for July 2004 SpeciesEmission Chemical (P-L) Dry Deposition Wet Deposition Net Export NO x 386-33744------5 PANs 2413------11 ∑ANs ANs 187.43.67 R 4 N 2 100.5-------10 HNO 3 277180110-3 Organic compounds may have much larger impact on global nitrogen cycling than previously thought! Funded by NOAA CPO program, titled “Impact of organic nitrate chemistry on air quality and climate: past, present and future atmospheres” for 2013-2016. Export of ∑ANs > Export of PANs

27. New chemistry Previous studies without NO x recycling Anthro NO x emissions in 2004 Reduce anthro NO x emissions of 2004 by 50% Isoprene↑ NO x ↓ OH ↓ O 3 ↓ due to O 3 +ISOP Surface ozone response to isoprene emissions: Implications for future air quality NO x emissions↓ Sensitivity of ozone to isoprene emissions ↓ (Mao et al., submitted to JGR)

28. NO x emissions has been reduced by 34% from 2005 to 2011 OMI NO2 column in 2005 (summer) OMI NO2 column in 2011 (summer) difference (Russell et al. 2012, ACP)

29. AM3 with updated chemistry

30. Updated chemistry Standard AM3 Observations CASTNET sites

31. Improvement on ozone over SE US (Naik et al., 2013, JGR, in press) Bias is reduced from 12.9 ppbv to 3.3 ppbv. This should be reexamined by MDA8 ozone. Model tends to overestimate monthly mean ozone. Standard AM3 New chemistry in AM3 (C48 2001-2005)

32. Field studies over Southeast US in this summer SENEX (NOAA) SOAS (NSF & EPA) NOMADSS (NCAR) Two aircrafts based at Smyrna, TN and a tower located at Centerville, Alabama. Measurements include VOC, NO x, ozone, aerosols, CCN etc. GFDL will submit C180 nudge simulations to SENEX data archive. A modeling workshop to be held in Rutgers U.

33. GFDL AM3 configuration for SENEX Fully coupled chemistry-climate model o Parameterizes aerosol activation into liquid cloud droplets o solves both tropospheric and stratospheric chemistry over the full domain Nudging wind with GFS meteorological field High resolution (50 x 50 km) and coarse resolution (200 x 200 km) MEGAN biogenic emissions (process-based emission) Anthropogenic emissions use RCP 8.5 scenario (0.5 x 0.5 degree) New heterogeneous chemistry (Mao et al., 2013a, ACP; 2013b, GRL) New isoprene chemistry (Mao et al., submitted to JGR) C48 (200 x 200km) C180 (50 x 50km) Monthly mean ozone for July of 2012

34. Model of Emission of Gases and Aerosols from Nature (MEGAN) Process-based emission inventory Temperature dependence Light dependence Leaf age Emission factor Fractional coverage Leaf Area Index

35. HCHO measurements in boundary layer for all flights in June Monthly mean surface HCHO concentrations for June of 2012 Preliminary results from aircraft observations and AM3 C180 nudging simulation

36. One flight on June 03, 2013 Ozone (obs vs. model) HCHO (obs vs. model) Model does not show ozone bias. Model shows good agreement with HCHO. Time Flight altitude

37. 1.Evaluate anthropogenic and biogenic emissions in AM3 over southeast US (aircraft, model and satellite). 2.Evaluate model simulation of ozone, SOA precursors from aircraft and ground measurements. 3.Implement a new module of in-cloud SOA processing from Liu et al. (2012). 4.Evaluate organic aerosol simulations (organic aerosols in particular) and its implications for future and past atmosphere. The “role of aerosols in regional climate” was recently identified as an important crosscutting research challenge for NOAA in the report “Toward Understanding and Predicting Regional Climate Variations and Change”. AM3 simulations on SENEX campaign A new module of in-cloud SOA production developed in AM3 (Liu et al., 2012, JGR) Question: What are the formation mechanisms of secondary species (ozone, sulfate and organics) in the SE U.S.?

38. We implemented a new set of chemistry in AM3, which significantly improves model simulation of ozone over SE US. This updated chemistry show significant impact on global OH, CO, O 3, nitrogen cycling, and have important implications on predicting future climate change and air quality. GFDL is participating NOAA SENEX campaign with C180 nudging model. Overestimate of ozone (puzzle 1) may be significantly improved from this study Underestimate of organic aerosols (puzzle 2) can be at least partly improved in the model. Conclusions

39. Sunrise Entrainment zone Model shows large amount of VOCs and OVOCs in the residual layer. Is it possible to do a early morning flight to see the entrainment zone? Boundary layer structure by Stull (1988). Does nighttime chemistry affect global nitrogen/ozone budget? Sunset

40. HCHO yield at different NO x conditions Computed in a photochemical box model. Initialized with 1ppb isoprene. O 3 (40ppb), CO (100ppb), and NO x are held constant. Prompt HCHO formation, important for deriving isoprene emission from satellite observations. Yield of HCHO is lower at lower NO x concentrations, according to the model. But the model could be wrong!

41. SO 4 NO x BVOCs Current limitation: We have no constraints on these SOA precursors. BC OC Aqueous reactions in cloud droplets Direct uptake of organic compounds by aerosols SOA precursors (Glyoxal, methyl glyoxal etc.) SOA Cloud evaporates SOA Two new pathways for SOA formation

42. O3O3 O2O2 O3O3 OHHO 2 h, H 2 O Deposition NO CH 4, CO, VOCs NO 2 STRATOSPHERE TROPOSPHERE 8-18 km Tropospheric ozone chemistry Air Quality Climate h h

43. Annual average aerosol loading from IMPROVE site Ammonium sulfate Organic aerosols Surface measurements show low fraction of organic aerosols

45. Nighttime chemistry Based on Rollins et al. (2009) and Xie et al. (2012) Nighttime yield of organic nitrates is 70%>> daytime yield (11.7%)

46. This chemistry was implemented in GEOS-Chem Ozone in the boundary layer during ICARTT 2004 Observations Model Obs vs. Model Improved O 3 -CO correlations due to: 1.Recycling of NO x from isoprene nitrates 2.HO 2 uptake (lower OH and increase NO x lifetime). (Mao et al., submitted to JGR)

47. Mean vertical profiles during ICARTT O 3 has no bias in boundary layer and free troposphere. HCHO provides good constraint on isoprene emissions. Observations Model (GEOS-Chem) (Mao et al., submitted to JGR)

48. Total organic nitrates excluding peroxyacylnitrates (∑ANs) Model well reproduced ∑ANs. ∑ ANs is dominated by secondary organic nitrates (C3-C4). ∑ANs vs. HCHO∑ANs vs. O 3 Model well reproduced ∑ANs vs. HCHO and ∑ANs vs. O 3 correlations. These correlations cannot be reproduced by a fast isomerization channel of ISOPO 2. Vertical profiles Speciation of ∑ANs

50. SENEX 2013 field campaign Southeast Nexus Studying the Interactions Between Natural and Anthropogenic Emissions at the Nexus of Climate Change and Air Quality Where: Southeast U.S. When: Summer 2013 What: The focus of NOAA's field study includes GFDL modeling and ESRL CSD measurements using the NOAA WP-3D aircraft. Who: Investigators in this project include researchers from several universities, industries, and governmental agencies.

52. temperature, radiation, land use Human activity Air Quality climate ozone, aerosols NO x SO 2 Isoprene emission to future climate and air quality Biomass burning isoprene emission Lightning NO x CO NH 3 NO x

53. Isoprene oxidation process Isoprene nitrates