An update on AC&C activities Phil Rasch, Martyn Chipperfield, Sarah Doherty, A. R. Ravishankara

1. An update on AC&C activitiesPhil Rasch, Martyn Chipperfield, Sarah Doherty, A. R. Ravishankara • Ravi stepped down, Martyn replaced him • Progress report • Discussion/Advice on Activities • Ancillary Activities

2. Atmospheric Chemistry and Climate: Timeline • Summer/Fall, 2007: • AC&C Activity plans developed • AC&C liaisons initiate coordination with AeroCom, CCMVal, HTAP • March 2008: Conference call of AC&C Steering Committee • Review/discussion of activity plans (for 3 of 4 activities) • Agreement to arrive at workshop with detailed model run plans & example model run output • June, 2008: 2nd AC&C Workshop, joint w/ HTAP (Washington, D.C.) • Finalize activity model runs with engagement of all model groups, in close coordination with HTAP “next phase” plans • The Path Forward: • Mid-2008  2009: Model runs, publications • Late 2009: Models are “frozen” for next IPCC Assessment Revising the paradigm: (Phil’s opinion) No longer “preparing models to be used for IPCC runs”, but…. “Design, Facilitate, Coordinate some of runs relevant to IPCC”,

3. AC&C Initiative: Activities for Phase I Activity 1: 20 year Hindcast Peter Hess, Jennifer Logan, Oliver Wild Activity 2: What controls the vertical distribution of species. Step 1: Focus on 5 km -> tropopause José Rodriguez, Joyce Penner, Céline Mari, (CCMVal Andrew Gettelman?) Activity 3: Cloud-chemical interactions Currently on hold & (possibly) being re-defined Activity 4: Future Scenarios: Sensitivities & Uncertainties Drew Shindell, J-F Lamarque, Michael Schulz, (CCMVal Veronika Eyring) Needs Resuscitation at a later time

4. Activity 1: Hindcast Experiments Needed a coordinator/facilitator (e.g. some funding) • Just lined up Contributions from NASA, DOE, NOAA, EPA for a post-doc/research associate for 2 years We did not propose a single hindcast experiment from 1980But, a series of interrelated experiments Each hindcast experiment defined by: • a multi-year series (post-1980) • a clear objective grading criteria for evaluating model success. • a set of required diagnostics to facilitate model comparison and evaluation. • multi-year external forcings (e.g., emissions) needed to drive the simulations. • guidelines on the types of chemical models and meteorological fields that can usefully participate

5. Activity 1: Simple Tracer Hindcast (C. Nevison, M. Prather, N. Mahowald) Goal: Match the trends and variability of the nearly-inert trace gases CFCs and N2O as measured by stations of the ALE/GAGE network. Quantify importance of: -changing emissions -tropospheric meteorology -stratosphere-troposphere exchange variability. From Nevison et al., Interannual Growth Rate Anomalies: Match and AGAGE

6. Activity 1: Aerosol Hindcast(Michael Schulz, Mian Chin) Goals: Better understanding of: -regional and global satellite observed trends in AOD -regional differences in sulfate and black carbon deposition from the Arctic to the Alpes -temporal trends in aerosol concentration, composition, optical properties and deposition -emission trends of primary aerosols and aerosol precursor gazes -the impact of changing meteorology vs changing emissions on aerosol trends -dimming and brightening trends observed by surface radiation networks -the evolution of the anthropogenic aerosols perturbation of the Earth radiative balance To be run as part of AEROCOM From Ramanathan et al., 2005 Observed and simulated Surface Radiation Fluxes over India

7. Activity 1: Ozone Hindcast(Jennifer Logan, Peter Hess) Goals:quantify impact on tropospheric ozone of: -changes in emissions of ozone precursors (NOx, CO, hydrocarbons) -changes in methane -changes in ozone in the lower stratosphere -dynamical variability including STE, ENSO, NAO/AO From Ordonez et al. Interannual Ozone Variations and trends.

8. Activity 1: Methane Hindcast (I. Bey, F. Dentener, A. Fiore, P. Hess, P. Bergamaschi) • Goal: Match the observed methane trends and variability. • Quantify: • -the importance of changing anthropogenic and natural emissions • the importance of OH variations. • Procedure: • use OH fields from the ozone hindcast in an inverse modeling calculation for methane emissions – reconcile top-down and bottom-up emission estimates. From Wang et al, Modeled and Observed changes in CH4 growth rate.

9. AC&C Initiative, Activity 1: Hindcasts • For models with ‘whole atmosphere’ chemistry needs to build on recent CCMVal REF-B1 simulations (1960-2005). • Full chemistry specifications need to include stratospheric forcings and boundary conditions…. Default is to take REF-B1 input. • As ‘stratospheric’ model runs should start ~1960, tropospheric emissions need to be prescribed from this date.

10. AC&C Activity 4 – “Future Scenarios”Drew Shindell, J-F Lamarque, Michael Schulz, (CCMVal Veronika Eyring) • Phase 1: ACC-MIP (focus on troposphere) • Time-slice experiments to complement AR5; CCMs and CTMs (need stratosphere) • Emission sensitivity studies • Sensitivity to IAM modeling of specific RCP • Spread from using climatology Timeslice runs including detailed chemistry diagnostics and separating aerosol indirect effects. Each run 4 years with prescribed SSTs taken from AR5 runs (SSTs should ideally be decadal means around given years), 2-month initialization suggested. 8 historical times (1850I, 1890, 1910, 1930, 1950 I, 1970, 1990, 2000 I) 5 future times (2010 I, 2030, 2050 I, 2070, 2100 I), each with 2.6 W/m2Representative Concentration Pathway (RCP), 4.5 W/m2 RCP and 8.5 W/m2 RCP.

11. AC&C Activity 4 • Phase 1: ACC-MIP • Timeslice experiments to complement AR5 (38 simulations, 160 years) • Emission sensitivity studies • Sensitivity to IAM modeling of specific RCP • Spread from using climatology Run at year 2050 (SSTs from #1), 1 year runs (+2-month initialization), model’s own distribution of given emission scaled uniformly: 2.1: +100 Tg isoprene 2.3: +20% biomass burning (all species) 2.4: +50 Tg methane (3 year run in this case, only applicable for models with sources/sinks of methane rather than prescribed) 2.5: +2 Tg N/yr lightning NOx

12. AC&C Activity 4 • Phase 1: ACC-MIP • Timeslice experiments to complement AR5 (38 simulations, 160 years) • Emission sensitivity studies • Sensitivity to IAM modeling of specific RCP • Spread from using climatology Same 4 year timeslice runs as in ACCMIP_1 for 2050 and 2100 but using emissions for the 2.6 and 4.5 RCPs from the other available IAMs. Runs without AIE only (as these are not climate runs)

13. AC&C Initiative, Activity 2: Vertical DistributionsJosé Rodriguez, Joyce Penner, Céline Mari, (SPARC representative AG?) What controls species distribution between 5km & tropopause?: • Advection by large-scale winds • Convection • Wet scavenging • Dry Deposition • Stratosphere-Troposphere Exchange (CCMVal, SPARC) • Chemistry • In situ production of ozone precursors -Start off looking at convection and scavenging processes, as these are the most uncertain and biggest “knobs” in the models, in particular when looking at UT.

14. Activity 2 – What to do? • Most of the discussion initiated by “senior” people with little time but lots of opinions/ideas • Need “heroes” -- people who actually get things done • Perhaps recent relevant activities may be exploited to enhance this activity. • CCMVal • SCOUT-O3 • Mary Barth’s convection intercomparison activity • AMMA

15. AC&C Initiative, Activity 2: Vertical Distributions SCOUT-O3 Results (Hoyle et al 2009) Comparison of CTMs, CCMs and mesoscale models Idealised tracers (e.g. 5-day lifetime) Comparison with Darwin CO profiles

16. Activities triggered and related to AC&C

17. Emissions An international effort was made to provide improved emissions 1850-2300, consistent across 2000 for anthropogenic (including shipping and aircraft) and biomass burning of reactive gases (not ODSs) and aerosols Historical (1850-2000) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols: methodology and application. Jean-François Lamarque, Claire Granier, Tami C. Bond, O. Cooper,.Veronika Eyring, Angelika Heil, Mikiko Kainuma, Z. Klimont, David Lee, Catherine Liousse, J. R. McConnell , Aude Mieville, S. Oltmans, Bethan Owen, D. Parrish. Keywan Riahi, Martin Schultz, Drew Shindell, Steven Smith, Elke Stehfest, Allison Thomson, John Van Aardenne, Detlef Van Vuuren,

18. Status • Emissions • 1850-2000: available since July for all reactive gases and aerosols (1850 and 2000 earlier) • 2000-2100: RCP4.5/RCP8.5 available for reactive gases and aerosols • Concentrations (decadal averages): atmosphere-only simulations • 1850-2000: ozone (V. Eyring) • 1850-2000: aerosols (including dust and sea-salt) to be made available soon. • 2000-2100: RCP4.5/RCP8.5 running (NCAR) • (Phil thinks) At least one RCP scenario still missing

19. Example of Impact of emissions(older versions, Flanner, McConnell and Rasch, unpublished)

20. Newer Emissions (Lamarque and Flanner, unpublished)

21. Remaining Issues • CCMVal desire to start hindcasts in 1960s • Trop focus started in 1980s • Hindcasts for troposphere would benefit from emissions with annual time scale resolution (or shorter) • E.g. fires • ?