Modelling of long-range transport of air pollution within the frame of the Task Force Hemispheric Air Pollution.

Transcription

1 Modelling of long-range transport of air pollution within the frame of the Task Force Hemispheric Air Pollution Martin Schultz, FZ, Jülich Oliver Wild, U. Lancester Arlene Fiore, GFDL, Princeton HTAP modellers 1

2 Intro to TF HTAP Purpose of and Participation in TF HTAP Created in December 2004 by the UNECE Convention on Long-Range Transboundary Air Pollution TF HTAP is organized under EMEP and engages with the EMEP Centres and other EMEP Task Forces. United States and European Community are the Lead Parties. To improve the scientific understanding of intercontinental transport and hemispheric air pollution in the Northern Hemisphere. Participation is open to all interested experts. Focus on the 7 science questions Coordinated model studies: provide harmonized information to the HTAP interim and final reports 2

3 Intro to TF HTAP Policy-Relevant Science Questions 1. How does hemispheric transport affect air pollution? 2. How much do emissions in one country or region affect air pollution in another country or region? 3. How confident are we of the results and what is our best estimate of the uncertainties? 4. How will changes in emissions in one country or region affect air pollution in another country or region? 5. How may the source-receptor relationships change over the next 20 to 50 years due to changes in emissions? 6. How may the source-receptor relationships change due to climate change? 7. What efforts are needed to develop an integrated system of observation data and models? 3

4 2007 Interim Report Focus on Ozone and Aerosols Serves as Foundation for 2010 Report Includes measurement-and model based analysis Pops/Hg in separate assessments. Major Findings (1) Observations from the ground, aircraft, and satellites provide a wealth of evidence that ozone and fine particle concentrations in the UNECE region and throughout the Northern Hemisphere are influenced by intercontinental and hemispheric transport of pollutants. The processes that determine the overall patterns of transport at this scale are relatively well understood and our ability to quantify the magnitude of transport is improving. 4

5 2007 Interim Report Major Findings (2) The HTAP model intercomparison has provided the first set of comparable estimates of intercontinental source-receptor relationships from multiple models. For ground-level ozone, there is a hemispheric background concentration of ppb that includes a large anthropogenic and intercontinental component. changes in intercontinental transport can have small, but significant, impacts on surface concentrations. For fine particles, the impact of intercontinental transport on surface air quality is primarily episodic, especially associated with major emission events such as fires or dust storms. The intercontinental transport of both ozone and fine particles has large impacts on total atmospheric column loadings, which have significant implications for climate change. 5

6 Wide range in literature estimates of mean surface O 3 S-R relationships at northern mid-latitudes Receptor = North America Receptor = East Asia Receptor = Europe Estimates are from studies cited in TF HTAP [2007] Ch5, plus new work [Holloway et al., 2008; Duncan et al., 2008; Lin et al., 2008] Assessment hindered by different: 1) methods 2) region definitions 3) reported metrics 4) years (meteorology) Adopt a multi-model approach Consistency across models Examine all seasons 6

7 Coordinated Model Studies Exp Set 1: Source Receptor Experiments Exp set 2: Tracer experiments that enhance understanding of the uncertainties Exp Set 3: Parallel detailed experiments for mercury, ozone, aerosols, campaigns Exp Set 4: Further assessment of uncertainties, and future scenarios. 7

8 Overview of experiment set 1 Source Receptor Relationships NA EU SA EA Importance and uncertainties of hemispheric transport processes for ozone and its precursors, particulate matter Using best emission inventory and meteorological dataset for Simulations consist of a reference simulation (2001), and simulations with anthropogenic emissions decreased in each region by 20 %. NOx, VOC, CO, CH4, aerosol: 18 experiments The four regions of interest for Source Receptor Relationships are Europe (EU), North America (NA), East Asia (EA), South Asia (SA). >25 models participated in Experiment 1 8

9 Global and regional NOx and VOC emissions GEOSChem-v07 MOZARTGFDL-v2 STOCHEM-v02 CAMCHEM-3311m13 INCA-vSSz LLNL-IMPACT-T5a EMEP-rv26 OsloCTM2 FRSGCUCI-v01 UM-CAM-v01 TM5-JRC-cy2-ipcc-v1 GEMAQ-v1p0 ULAQ-v02 STOC-HadAM3-v01 GISS-PUCCINI-modelE GISS-PUCCINI-modelA 9

10 Intercontinental Ozone SR relationships Ozone Response [ppbv] in Receptor regions due to 20 % anthropogenic Emission reduction Source Receptor Fiore et al, in preparation, [2008] NA EU E SAA 10

11 Intercontinental Ozone SR relationships Ozone Response [ppbv] in Receptor regions due to 20 % anthropogenic Emission reduction Source Receptor Fiore et al, in preparation, [2008] NA EU E SAA 11

12 Intercontinental Ozone SR relationships Ozone Response [ppbv] in Receptor regions due to 20 % anthropogenic Emission reduction Source Receptor Fiore et al, in preparation, [2008] NA EU E SAA 12

13 Intercontinental Ozone SR relationships Ozone Response [ppbv] in Receptor regions due to 20 % anthropogenic Emission reduction Source Receptor Fiore et al, in preparation, [2008] NA EU E SAA 13

14 PM receptor analysis Jointly with AEROCOM M. Schulz et al in preparation

15 TP1 (tracer studies): Concept all models use same emissions identical starting conditions (zero concentration) simple chemistry (exponential decay, lifetime 25 days) regional tagging (EU, NA, EA, SA) parameterized secondary formation (avoc, bvoc, CH4) 15

16 CO_direct, ca. 5 km, February results from a presentation by M. Schultz, October 2007) PRELIMINARY ppt * 0.04 pressure level closest to 540 hpa selected 16

17 CO East Asia July, ca. 5 km ppt *

18 CO Europe July, ca. 5 km ppt *

19 CO North America July, ca. 5 km ppt *

20 CO South Asia July, ca. 5 km??? 20

21 CO export into Arctic SR1-SR5 TP1 Averages computed over lowest 200 m 21

22 Boundary layer exchange Europe North America East Asia South Asia CO average m over CO average m; TP1 experiment 22

23 BL exchange ratio East Asia surface = m surface = lowest layer model spread somewhat reduced, but still almost a factor of 2! 23

24 Now running: TP1x lifetime extended to 50 days 1-year spin-up additional VOC tracers with different lifetimes=>provides link to measurements 24

25 Hydrocarbon clocks Observations Flexpart Model Results 25 David Parrish

26 ECHAM5-MOZ results, 2nd year of simulation TP1 vs. TP1x: total CO TP1 TP1x January Year 2 July Year 2 surface level identical emissions 25 days lifetime 50 days lifetime ppb 26

27 TP1 vs. TP1x: CO from East TP1 Asia TP1x January Year 2 July Year 2 surface level identical emissions 25 days lifetime 50 days lifetime ppb 27

28 TP1 vs. TP1x: CO from Europe TP1 TP1x January Year 2 July Year 2 surface level identical emissions 25 days lifetime 50 days lifetime ppb 28

29 TP1 vs. TP1x: CO from bvoc TP1 TP1x January Year 2 July Year 2 surface level identical emissions 25 days lifetime 50 days lifetime ppb 29

30 Concluding remarks 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 ppbv to 20% ant. emission reduction in all 4 regions. Methane can play an important role as well (about half of the convential air pollutants) Model sensitivities combined with estimated emission trends can only partly explain observed ozone trends Link to regional scale: most advanced with MICS Asia community EDGAR-HTAP database: includes regional inventories in global framework. Future work: Scenarios and linearization of results More emphasis on possible effects and impacts. 30

31 Concluding remarks II TP1 is proof of concept : success in terms of identifying model differences due to transport Transport patterns qualitatively consistent, also with FLEXPART Boundary layer mixing varies between models by a factor of 2 TP1x will generate more realistic CO fields which can be better tied to SR analysis Participation in TP1x still possible- other communities ( TRANSCOM? may use results 31