1. Linking global scale and European scale modelling:
Hemispheric Transport of Air pollution
Frank Dentener
JRC
Andre Zuber
ENV
Terry Keating
US EPA
and HTAP authors/contributors

2. Task Force Hemispheric Transport of Air Pollution (TF HTAP)
Established in 2004 by UNECE
Interim report 2007
HTAP Assessment report 2010
Mandate:
Examine the transport of air pollution across the Northern Hemisphere,
ozone and its precursors and PM and its components
(including black carbon)
Assess potential emission mitigation options available inside and outside
the UNECE region
Assess their impacts on regional and
global air quality, public health, ecosystems,
near-term climate change
Collaboration with other groups both inside and outside the Convention.

3. HTAP 2010 Report 4 volumes, 826 pages, 178 contributors
Covers O3, PM, Hg, POPs
Contents addresses:
Conceptual Models
Observed Spatial & Temporal Trends
Emissions Inventories & Projections
Global & Regional Modeling of Pollution Transport
Impacts to Health, Ecosystems, & Climate
Available electronically at Available in print on request
The Task Force on Hemispheric Transport of Air Pollution under the LRTAP Convention has recently completed an assessment of the intercontinental transport of air pollution across the Northern Hemisphere experts from around the world contributed to the report, which comprises 4 volumes addressing ozone, fine particles, mercury, and persistent organic pollutants.
The report is available electronically from the Task Force website, and will be available soon in printed form. 3

4. Pathways of hemispheric pollution transport
CO passive tracer
Lower troposphere
Mid-upper troposphere
Figure A1-4. Pathways of intercontinental pollution transport in the Northern Hemisphere. Shading indicates the location of the total column of a passive anthropogenic CO tracer released over the Northern Hemisphere continents after 8-10 days of transport, and averaged over 15 years. Shown are transport pathways in summer (June, July, August) (upper panel), and winter (December, January, February) (lower panel). Gray arrows show transport in the lower troposphere (< 3 km) and black arrows show transport in the mid- and upper troposphere (> 3 km). Image reproduced from Chapter 1, Figure 2, page 6, of Stohl, A
Flexpart, A. Stohl et al, 2004

5. MACE HEAD, WEST COAST IRELAND:
change in O3 between and
Change in global baseline O3?
Change in meteorological conditions?
Is this happening everywhere along the borders
of Europe?
How does this impact air quality in Europe?
Courtesy D. Derwent, K. Law

6. Measurements at Mount Batchelor, US West Coast
Several surface stations and satellite analysis show intercontinental transport
Plume transport versus ‘diffusive’ background transport
the magnitude and importance of these transports from combination
of models and measurements

7. HTAP: Design of Multi-Model ExperimentsNA EU EA SA
Source-Receptor Sensitivity Simulations:
Base Year 2001
>20 global models
Decrease emissions of precursors in each region by 20%
Precursors emission include
NOX, VOC, CO, NOX+VOC+CO,
NOX+VOC+CO+PM
Hg, POPs
CH4 concentration
One of the unique contributions of the Task Force has been the organization of a series of multi-model experiments to quantify intercontinental transport. More than 30 modeling groups from around the world have participated in one or more of these experiments.
In the first phase of these experiments, the Task Force defined a set of sensitivity analyses, looking at 20% decreases in emissions from 4 continental regions that approximate North America, Europe, South Asia, and East Asia.
These experiments demonstrated that pollution within any of the regions is most sensitive to changes in emission sources within that region. However, every region could also benefit significantly from emission controls outside the region. 7

8. HTAP policy relevant metric
RELATIVE ANNUAL INTERCONTINENTAL RESPONSE
R= annual average response to emission perturbation
Under current conditions: if everywhere in the world the same emission reductions were applied,
what would be in the EU the relative contribution of pollution from abroad?

9. RAIR for air pollution, climate and ecosystem metrics
“Ecosystem Impacts”

10. Emissions: EDGAR-HTAP
National and regional inventories, complemented with EDGAR global emissions
Policy consistency
Consistent high resolution emissions databaseTF HTAP base year calculations

11. HTAP reconstruction of regional ozone changes:
period ; attribution of drivers. NA EU EA SA
Surface O3 change [ppbv]
Source Receptor relationships from ca. 10 global models
Global emissions trends of precursors ( )
Reconstruction of the past O3 trends
Source attribution
O. Wild et al., ACPD, 2011

12. HTAP reconstruction of regional ozone changes:
period ; attribution of drivers. NA EU EA SA
Surface O3 change [ppbv]
Contribution to O3 change [ppbv]

13. HTAP reconstruction of O3 changes in EU: attribution of drivers.NA EU EA SA
Annual average - large region
Small reductions in O3 during ,
largest changes (6 ppbv) happened before.
O3 reductions attributable to EU emissions partly
compensated by increasing emissions elsewhere
Important role for (global) CH %
Total change
Within EU
Outside of EU
Methane

14. HTAP reconstruction of O3 changes in EU: attribution of drivers.NA EU EA SA
Annual average - large region
Small reductions in O3 during ,
largest changes (6 ppbv) happened before.
O3 reductions attributable to EU emissions partly
compensated by increasing emissions elsewhere
Important role for (global) CH %
Taken together changes in O3 from outside EU
and CH4 are larger than within EU (60-70 %)
External O3 becomes more important when
‘local’ source are more regulated.
More important at ‘lower’ concentrations
Total change
Within EU
Outside of EU
Methane

15. TF HTAP Future Directions
Deliver Policy Relevant Information to the LRTAP Convention, Other Multi-Lateral Forums, and National Governments and EU
Fraction of air pollution concentrations attributable to emission within region compared to extra-regional.
Impacts on human health (Global Burden of Disease), ecosystems (WGE) and climate change (IPCC)
Sensitivity to changes in specific sources (e.g. ships)
Change of impacts and fractions under expected air pollution abatement efforts or climate change:
scenarios and control options: focus on Black Carbon, Methane, Mercury
e. Comparison of the availability, costs and impacts of additional emission abatement options across different regions
Improve Our Scientific Understanding of Air Pollution at the Global to Hemispheric Scale
Emissions: EDGAR HTAP
Various source apportionment methods
Linking of global and regional models
Model-Observation Evaluation and Process Diagnosis
Build a Common Understanding by Engaging Experts Inside and Outside the LRTAP Convention

16. EC ENV contract on Hemispheric Transport
Model simulations in the frame of TF HTAP, but focus on EU and review
Contractor: MetNo, IIASA, FZ Julich, assisted by JRC
Timeframe: 11/ /2013
Emission scenarios and control options
Contribute to multi-model analysis and evaluation in TF HTAP
Provide dedicated information on the impact of past and future changes in boundary conditions on EU Air Quality