An update on AC

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An update on ACC activitiesPhil Rasch, Martyn
Chipperfield, Sarah Doherty, A. R. Ravishankara

• Ravi stepped down, Martyn replaced him
• Progress report
• Discussion/Advice on Activities
• Ancillary Activities

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Atmospheric Chemistry and Climate Timeline
Summer/Fall, 2007 ACC Activity plans
developed ACC liaisons initiate coordination
with AeroCom, CCMVal, HTAP March 2008 Conference
call of ACC 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 ACC 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 (Phils opinion) No longer
preparing models to be used for IPCC runs,
but. Design, Facilitate, Coordinate some of
runs relevant to IPCC,
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ACC 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 -gt
  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
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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

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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
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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
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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.
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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.
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ACC 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.

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ACC Activity 4 Future ScenariosDrew
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/m2 Representative
Concentration Pathway (RCP), 4.5 W/m2 RCP and 8.5
W/m2 RCP.
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ACC 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), models 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
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ACC 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)
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ACC 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.

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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 Barths convection intercomparison activity
• AMMA

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ACC 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
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Activities triggered and related to ACC
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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-Franço
is 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,
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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

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Example of Impact of emissions(older versions,
Flanner, McConnell and Rasch, unpublished)
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Newer Emissions (Lamarque and Flanner,
unpublished)
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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
• ?