Tropospheric bromine in GEOS- Chem: Impact on preindustrial and present-day ozone

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Tropospheric bromine in GEOS- Chem: Impact on preindustrial and present-day ozone Parrella, Justin P. (parrella@fas.harvard.edu) 1 M. J. Evans, D. J. Jacob 1, L. J. Mickley 1, B.

School of Engineering and Applied Sciences, Harvard University, Cambridge MA, United States.

Goddard Earth Sciences & Technology Center, University of Maryland, Baltimore County, MD, United States 4.

1 Tropospheric bromine in GEOS- Chem: Impact on preindustrial and present-day ozone Parrella, Justin P. 1 M. J. Evans, D. J. Jacob 1, L. J. Mickley 1, B. Miller 1, Q. Liang 3, J. A. Pyle 4,5, X. Yang 4,5, Y. Zhang 6, N. Theys 7, M. Van Roozendael 7 1. School of Engineering and Applied Sciences, Harvard University, Cambridge MA, United States. School of Earth and the Environment, University of Leeds, Leeds, United Kingdom 3. Goddard Earth Sciences & Technology Center, University of Maryland, Baltimore County, MD, United States 4. National Centre for Atmospheric Sciences (NCAS), Cambridge, United Kingdom 5. Centre for Atmospheric Sciences, Department of Chemistry, University of Cambridge, Cambridge, United Kingdom 6. Department of Atmospheric Sciences, University of Washington, Seattle, Washington, United States 7. Belgian Institute for Space Aeronomy (IASB-BIRA), ussels, Belgium funding from: NASA Atmospheric Composition Modeling and Analysis Program, NERC, NCAS, and NSF graduate research fellowship.

2 GEOS-Chem bromine simulation Observations show.5 - ppt O. How can we reproduce this in a model of tropospheric chemistry? Impose Stratospheric Loss y O x Chemistry: i. gas-phase ii. photolysis iii. heterogeneous 1. NO3 hydrolysis. HO + H + aer. O 3, Hg destruction Deposition: H, HO, ON, Ox = + O Photochemistry Major Emissions: i. CH 3 ii. sea salt aerosol Fumigants, gasoline ocean, biomass burning, salt marshes, wetlands... * can impose conc. as dynamic boundary condition iii. snow pack young polar sea ice, leads, polynyas? snow pack iv. macroalgae: VSLs: CH 3, CH, etc.

3 GEOS-Chem bromine simulation details Total column comparison observations: INTEX-A and B, TRACE-P, ARCTAS Springtime, Pacific mid-latitudes observations: INTEX-B, TRACE-P [Schauffler et al., 1999; Blake et al., 3] industry CH3 CH CH3 sea salt macroalgae 1.1 years 91 days hv, 1 days debromination y Source (Gg /yr) ~5 57 Altitude (km) 1 9h,! Mid-latitude CH3 evaluation Tropospheric Column, 1 8 molec. / m J F CH 3 (ppt) Model Observations M A M J J A S O N D Month Mean tropospheric concentrations in ppt.1 ppt.7.3 O NO3 H 4h, Het HO.9 GEOS-Chem deposition y 4-1 d

4 Simulated and Observed O Tropospheric O columns (#/cm ), present day 8 x ºN GEOS-Chem p-tomcat GOME- - BASCOE Tropospheric O [Theys et al., 1] Difference between GEOS-Chem and TOMCAT? HO + H + aer. - HO is limiting - TOMCAT γ =. - GEOS-Chem γ =. J F M A M J J A S O N D 8 x ºS J F M A M J J A S O N D Month ~ 1 ppt [O] GEOS-Chem annual zonal mean [O]: Altitude, (km) Latitude Latitude 1.5

5 Mickley et al., 1 Month Is O important for natural tropospheric ozone? Motivation: - Natural O3, an important reference point 1. Air quality: how much ozone can we regulate?. Climate: a larger radiative forcing for trop. O3? Ox-driven global trop. ozone loss: two dominant catalytic cycles - Models overestimate preindustrial obs. 1. Schönbein observations could be wrong.. Are we missing a sink for tropospheric ozone? - Tropospheric bromine is not included in standard models of the natural atmosphere. Questions: Standard models overestimate observations from turn of th century 1. What is the significance of bromine chemistry on natural tropospheric ozone?. Can it improve agreement with ozone measurements from a century ago? Ozone (ppb) Observed Model

6 Comparison to turn-of- th century measurements Ozone (ppb) JFMAMJJASOND Montsouris (5ºN, ºE) Tokyo (35 N, 139 E) JFMAMJJASOND Month GEOS-Chem, no Ox GEOS-Chem with Ox p-tomcat, no Ox p-tomcat with Ox Observations HOx and Ox (#/cm 3 ) Treating Ox improves agreement with turn of the th century measurements of surface ozone substantial [Ox] when low competition from HOx natural air, northern mid-latitudes Preindustrial: HOx and Ox over Northern Midlatitudes Month Ox HOx J F M A M J J A S O N D

Impact on present-day ozone 1 8 4 6 8 Hohenpeissenberg (48 N) April Syowa (69 S) GEOS-Chem with bromine January 4 8 1 16 4 8 1 16 Ozone (ppb) GEOS-Chem without bromine Sondes Logan [1999] Sondes show

7 Impact on present-day ozone Hohenpeissenberg (48 N) April Syowa (69 S) GEOS-Chem with bromine January Ozone (ppb) GEOS-Chem without bromine Sondes Logan [1999] Sondes show mixed results New low biases in northern mid-latitudes Isoprene chemistry? recycling NOx vs. P(HNO3)? Emissions? Ship NOx, Streets bug-fix, soil, lightning? 5 hpa O3 due to bromine (yr. avg.) 4 Cape Verde, 7, altitude 1m Ozone (ppbv) 3 1 without bromine with bromine observations J F M A M J J A S O N D Month O 3 (ppb)

8 Extra slides

9 Some evidence for tropospheric -Chem Location MBL Color Key: (a) positive measurements, (b) mixed, (c) low estimates (~ ppt) Range of [O] 1. Mace Head. Roscoff, France ~ ppt 3. Cape Verde 4. Canary Islands (cruise) < d.l. or - 1 ppt Greater Troposphere 1. Equatorial Pacific. Kiruna (68 N, 1 E) 3. Reunion Island (1 S, 56 E) 4. Global, GOME- - BASCOE 5. Lauder, New Zealand 6. Arrival Heights, Antarctica 7. Teresina, azil Measurements of source gases 1. VSLs (CH3, CH, etc.): - ~ Decade of NASA flight measurements + cruise obs.. CH3 - CMDL surface network (Montzka et al.) + NASA flights 3. Sea salt debromination (parameterize in CTMs) - Depletion of ions in SSA [Sander 3] Modeling Known sources sustain ~1 ppt O background [Yang 5] VSLs net: O 3 + H = + net: O 3 + N = + HO y H O d - 4 mon immediate Ref s 1. Saiz-Lopez et al. 4; 6;. Mahajan et al Read et al. 8; Mahajan et al Leser et al. 3; Martin et al ppt 1. Rozanov et al.. Fitzenberger et al., ; Hendrick et al Theys et al Theys et al. 1. +/-. ppt ~ ppt 5. Schofield et al Schofield et al Dorf et al. 8 O 3 ~ 464 Gg yr -1 ~ 1-3 Tg yr -1 seasalt debromination H CH O HNO 3 HO aer. NO 3 N O O 3

10 Example measurements of tropospheric O Mace Head: avg..5; max 6.5 ppt Saiz-Lopez et al. 4; 6 Roscoff, France: up to 7.5 ppt Mahajan et al., 9 Cape Verde: - 3 ppt Read et al., 8; Mahajan et al., 1 Our Models: ~.5 ppt in daytime NH B.L none mixed 1ppt Fitzenberger et al., ; Hendrick et al. 7 Measurement type MBL/Coastal measurements LP-DOAS Ground or ship-based DOAS Balloon DOAS Indirect obs. (diurnal O3, Hg) Van Roozendael et al., Fraser et al., 9 Holmes et al ppt, equatorial pacific GOME cloud slicing Richter et al.,.5 - ppt, Global SCIAMACHY - BASCOE stratosphere Theys et al., 1 Our models correspond well to Theys et al., 1 ppt Dorf et al. 8 Cruise: - 1 ppt twice ppt rest Leser et al., 3; Martin et al. 9 Dead Sea > 6 ppt ~ ppt in F.T. Theys et al., 7 Galbally et al. 1. +/-. ppt Schofield et al. 4; 6 Holmes et al., 9

11 Impact on radiative forcing? No This work.34 W/m Approximate mean RF to change in tropospheric O3 column [DU]: RF (W/m ) =.34 x ΔDU [mickley et al., 1999] Previous studies do not account for tropospheric halogen chemistry..35 W/m mean from IPCC reported values. We find that bromine chemistry Essentially negligible for O3 RF. Caveat: New ozone biases in the present-day model IPCC figure adapted from IPCC. 7

12 Source gas maps 9 o N 6 o N 3 o N o SSA emissions Annual Fluxes: 1. SSA: 7 Gg/yr. CH3: 47 Gg/yr 3. CH: 57 Gg/yr 4. CH3: ~5 Gg/yr 3 o S 6 o S 9 o S 18 o 15 o W 1 o W 9 o W 6 o W 3 o W o 3 o E 6 o E 9 o E 1 o E 15 o E 18 o VSL emission map.e+ 7.67e e-13.3e e e e-13 SS [kg/m/s

13 Industrial atmosphere w/ SSA (no NH variation in DF): 8-16, -8km O3 loss cycles Aug. 6 model run: Lifetimes for each rxn. d= days, h= hrs, m = min, s = sec O (.78 ppt) O NO HO NO, M O 3.6 m 3.4 h h 54.6 s s 14 d 3.4 m 31 m 1 h.6 h O3 NO3 (.9 ppt) HO CHO NO, M.9 h 7.8 m 8 h 5 m.3 m H (5. ppt) NO (.47 ppt) 15 m HO (1.5 ppt) 5 m het. 38 m.3 h 1. m 1.5 h 3.7 h ONO (.1 ppt) (.11 ppt) 1. h

14 Overview: Tropospheric ozone loss by O omine in the troposphere: - Most observations:.5 -. ppt O global background - Decrease in Ozone: 4-18% in zonal mean; up to 3 % in SH [von Glasow, 4; Yang 5] - potentially larger regionally [von Glasow 4] - Increases NO/NO and /HO ratios -driven O3 loss: - gas phase - 9% in UT - 4-5% below - NO3 Hydrol % - clouds mostly net: O 3 + H = + net: O 3 + N = + HO y H O d - 4 mon immediate ~ 464 Gg yr -1 ~ 1-3 Tg yr -1 two dominant catalytic cycles O 3 H CH O 4-1% of NO + NOx loss HNO 3 HO aer. NO 3 N O O 3 VSLs seasalt debromination

15 GEOS-Chem bromine simulation Observations show.5 - ppt O. How can we reproduce this in a model of tropospheric chemistry? Largest uncertainties in y Budget - Important for future work Impose Stratospheric Loss y O x Chemistry: i. gas-phase ii. photolysis iii. heterogeneous 1. NO3 hydrolysis. HO + H + aer. O 3, Hg destruction Deposition: H, HO, ON, Ox = + O Photochemistry Major Emissions: i. CH 3 ii. sea salt aerosol Fumigants, gasoline ocean, biomass burning, salt marshes, wetlands... * can impose conc. as dynamic boundary condition iii. snow pack young polar sea ice, leads, polynyas? snow pack iv. macroalgae: VSLs: CH 3, CH, etc.

16 Simulated and Observed O Tropospheric O columns (#/cm ), present day 8 x ºN J F M A M J J A S O N D 8 x GEOS-Chem p-tomcat 3-6ºS J F M A M J J A S O N D Month GOME- - BASCOE Tropospheric O [Theys et al., 1] ~ 1 ppt [O] GEOS-Chem annual zonal mean [O]: [O]preindustrial [O]present +.5 ppt Altitude, (km) Altitude (km) Altitude, km Preindustrial Latitude Present-day Latitude

17 Overview: omine in GEOS-Chem 1. Full gas phase chem. and photolysis. Het. Chem: (1) NO3 hydrolysis, () HO + H + aer 3. Deposition (, HO, H, NO3) 1 omine tracers:, O, HO, H, NO, NO3, CH3, CH, CH3, Very Short Lived (VSL) gases Liang et al. [1] fixed in PBL based on observations Sea salt debromination. Yang et al. [5; 8] We need HO + H heterogeneous recycling to sustain.5 - ppt O, and agree with most obs. [platt and hönninger, 3] In contrast to previous results, influenced by bug in convection module, caught by Yanxu Zhang. VSLs net: O 3 + H = + net: O 3 + N = + HO y H O d - 4 mon immediate O 3 ~ 464 Gg yr -1 ~ 1-3 Tg yr -1 seasalt debromination Two dominant catalytic cycles H CH O 4-1% of NO + NOx loss HNO 3 HO aer. NO 3 N O O 3

Effect of bromine chemistry on natural tropospheric ozone: improved simulation of observations from the turn of the 20 th century

1 Effect of bromine chemistry on natural tropospheric ozone: improved simulation of observations from the turn of the 20 th century Justin P. Parrella 1, Mathew J. Evans 2, Daniel J. Jacob 1, Qing Liang