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observations
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• Convention of UNECE (United Nations Economic
  Commission for Europe)
• The Convention addresses major environmental
  problems of the UNECE region
• The Convention has 51 Parties (European countries
  USA Canada)
• 8 protocols identify specific measures to be
  taken by Parties to cut their emissions of air
  pollutants (e.g. EMEP Protocol)
• Parties develop policies and strategies to combat
  the discharge of air pollutants through exchanges
  of information, consultation, research and
  monitoring.

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TF HTAP

• The Task Force on Hemispheric Transport of Air
  Pollution was established in December 2004.
• The Task Force estimates the hemispheric
  transport of
• ozone and its precursors
• fine particles
• acidifying substances
• mercury
• persistent organic pollutants
• Hemispheric transport may be important for
  understanding air pollution problems in
  population centers and impacts on remote areas.
• The Task Force reports its findings to the
  Conventions Steering Body of EMEP.
• HTAP has initiated a comprehensive modeling study
  to assess the importance of intercontinental
  transport of air pollution.

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• www.htap.org
• HTAP Interim report June 2007 (downloadable).
• Final report Middle of 2009.
• TF HTAP jointly chaired by US EPA, EC/DG ENV.

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Experiment Set 1
Source Receptor Relationships     F. Dentener, A.
Fiore

• First insight about the importance and
  uncertainties of hemispheric transport processes
  for ozone and its precursors, particulate matter
• Using best emission inventory and
  meteorological dataset for 2001.
• Simulations consist of a reference simulation
  (2001), and simulations reducing their
  anthropogenic emissions per region by 20 .
• The four regions of interest for Source Receptor
  Relationships are Europe, North America, East
  Asia and South Asia.
• gt20 models participated in Experiment 1, 5 more
  in the SR1 only

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Experiment Set 1
www.htap.org
EU
NA
EA
SA
1. SR1 base case (methane prescribed 1760 ppb)
2. SR2 global methane reduction by 20 (1408
ppb)
3. 4x SR3 regional NOx reduction by 20
4. 4x SR4 regional NMVOC reduction by 20
5. 4x SR5 regional CO reduction by 20
6. 4x SR6 regional reduction of all
anthropogenic emissions by 20
__________________________________________________
______ 18 experiments in total (each at least 18
months simulation time)
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Other experiments

• Experiment Set 2 Processes and tracer studies
  (M. Schultz, O. Wild D. Shindell)
• To develop a simple set of diagnostics that can
  be used to understand the model differences that
  occurred under Experiment 1.
• Experiment Set 3 Detailed experiments for
  Mercury, Ozone, Aerosols, POPs,  linkage to
  campaigns (I. Bey), climate change, regional
  scale issues.
• There are a number of issues relevant for HTAP,
  that can be studied with coordinated experiments.
  These experiments will asses in more details
  processes relevant for HTAP.
• Experiment Set 4 Improved sets of Source
  Receptor experiments
• Yet to be defined, further assessment and future
  scenarios

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Which resolution do we choose?
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Global NOx and VOC emissions
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Seasonal cycles in simulated surface O3 over the
HTAP regions
SR1 results from 20 individual models including 5
twins
Model range spans 15-30 ppbv
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Seasonality Monthly mean surface O3 changein EU
from 20 reductions of domestic NOx emissions
? Large seasonality masked by annual mean
statistic
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Intercontinental Ozone SR relationships
Ozone Response ppbv in Receptor regions due to
20 ant. Emission reduction
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Intercontinental Ozone SR for Europe
foreign
foreign
foreign
foreign

• 20 perturbation of anthropogenic emissions in
  specific regions
• Combined influence of 3 foreign regions emission
  reductions similar to
• that in the domestic regions
• NOx and VOC have the greatest influence- weak
  non-linearity
• Ratio Emission NOx/Emission VOC0.240.11

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Intercontinental Ozone SR for North America
foreign
foreign
foreign
foreign

• NOx the greatest influence
• Ratio Emission NOx to Emission VOC0.150.06
  half that of Europe
• Combined influence of 3 foreign regions emission
  reductions half to
• that in the domestic regions

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NOy deposition Source-Receptor analysis
Where do NO emissions from Europe go to?
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NOy deposition Receptor-Source analysis
If we would change NO emissions in all 4 regions
by 20 how would it influence a receptor
region?
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PM receptor analysis
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Conclusions

• Perturbation experiments for 4 world regions
• NOx, CO, VOC, SO2, EC, POM, CO (Hg Pops).
• Model spread in perturbation signal typically
  factor of 2
• Ozone sensitivities ca. 1.5-2 ppbv to 20 ant.
  emission reduction in all 4 regions
• NAgtEU twice as large as all other SR relations
• Role of methane is an open issue
• Resolution dependency of seasonal differences
• Episode analysis
• Tracer experiments indicate that BL mixing among
  models varies between 40 and 80
• Relatively much attention to interoperability CF
  conventions

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The role of observations

• The first phase of HTAP had very little focus on
  observations
• However, most models participated previously in
  PHOTOCOMP and AEROCOM intercomparisons
  (2004-2006)
• Tight timeschedule
• It was felt that the models in HTAP would not
  give very different results
• AEROCOM (http//nansen.ipsl.jussieu.fr/AEROCOM/)
• Considers surface chemistry observations
  satellite AOD/Angstrom, Aeronet, EARLINET.
• AEROCOM workshop 25/26 October, Lille.

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Sonde data Logan (1999) SHADOZ (Thompson et
al, 2003
)
Sonde 1SD
Model 1SD
UT 250 hPa
J F M A M J J A S O N D
Stevenson et al., JGR, 2005
MT 500 hPa
LT 750 hPa
90-30S 30S-EQ EQ-30N
30-90N
Ensemble mean model closely resembles ozone-sonde
measurements
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Monthly average Surface ozone comparison with
measurements
S.W. US
S.E. US
Great Lakes
N. China
Brazil
C.E. Africa
S. Africa

• Max models
• 1 sd
• 1 sd
• Min models

C. Europe
C. Mediterranean
N. India Nepal
Middle East
S. India
S.E. Asia
Ellingsen et al, ACPD, 2007
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CO comparison with MOPITT
NH
GLOBAL
Individual models
SH
TROPICS
Shindell et al, JGR, 2006
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NO2 column retrievals and models
Van Noije et al, ACP, 2006
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HNO3 wet deposition models and measurements
EMEP
NADP
Kulshrestha
EAnet
IDAF
Various
Galloway
Dentener et al., GBC, 2006
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• Next phase of HTAP(2007-2009)
• Climate, regional, tracer experimentsgt2009
  report.
• More linkage to observations e.g. model
  experiments are planned focusing on campaigns
  TRACE-P ICARRT-INTEX. The base years for
  consideration are 2001/2004.
• Strong need for accepted benchmark datasets, to
  which models and their updates can be routinely
  compared. QA-QC fit-for-purpose.
• What are the quality criteria for these
  benchmark datasets?
• Interoperability of model data will help.
• NILU will select surface observations for
  establishing benchmark datasets
• Satellite data?