Basic task for the experience

1. Danish experience in modeling area on country, regional and global levels in thecontext of model review Jesper H. Christensen Lise M. Frohn, Jørgen Brandt, Camilla Geels, Kaj M. Hansen National Environmental Research Institute Department of Atmospheric Environment Roskilde, Denmark

2. Basic task for the experience • Model review at all scales for us at NERI in Denmark has been strongly connected to model intercomparisons

3. Basic model for the experience • Danish Eulerian Hemispheric Model • Model based original on the Danish Eulerian Model (Zahari Zlatev) • Model development and review of the model system has been strongly connected to model intercomparisons • DEHM will be described in the following

4. First “model inter comparison” with DEM in 1991:

5. Another “model inter comparison” with DEOM in 2000:

6. The Danish Eulerian Hemispheric Model (DEHM) System

7. The Danish Eulerian Hemispheric Model (DEHM) System • The model work is financially supported by the Danish Environmental Protection Agency with means from the MIKA/DANCEA funds for Environmental Support to the Arctic Region • It is a part of the Danish contribution to the international AMAP programme • Purpose: Study the long-range transport in the troposphere of pollutants into the Arctic (now also the rest of the hemisphere). • Developed since 1991

8. The mathematical model Advection Diffusion Emission and wet deposition Chemistry

9. Numerical methods Horizontal advection: Vertical advection: Temporal advection: Filtering: Spatial diffusion: Temporal diffusion: Chemistry (1st step after adv.): 2nd and following steps: Modified Accurate Space Derivatives Finite Elements Taylor series to 3. order Forester filter, Bartnicki filter Finite Elements -method Backward Euler Two-step method

10. Model setup • Horisontal resolution : • Mother domain: 150 km x 150 km • 1. Nest over Europe: 50 km x 50 km • 2. Nest over Scandinavia: 16.67 km x 16.67 km • Vertical resolution : 20 layers up to app. 15 km • Meteorology : MM5 or Eta run operationally at NERI • New: ECHAM4 for 1961-2100 • Land use : Global inventory, 8 categories, Wilson and Henderson-Sellers, 1985

11. Model domains and resolutions Mother domain MM5: Northern hemisphere 150 km First nest MM5: Europe 50 km Second nest MM5: Scandinavia 16.67 km Mother domain ETA: Europe 50 km

12. Physical parameterisations Vertical dispersion: Horizontal dispersion: Dry deposition of gaseous components to land surfaces: Dry deposition of gaseous components to water surfaces: Dry deposition of particles to land surfaces: Dry deposition of particles to water surfaces: Wet deposition: K-theory of first order, Kz profile based on Monin-Obukhov similarity theory Constant values Resistance method Deposition velocity depends on the sea surface roughness Deposition velocity depends on friction velocity and height of vegetation as well as stability. Deposition velocity depends on the 10-m wind speed. Scavenging ratio formulation

13. DEHM flavours: • Sulphur: SO2, SO4 and lead (1991, 1999) (original taste) • CO2 (2001, 2004) • Chemistry: 64 species, e.g. O3, NH3 and NOX (2002, 2004) • Mercury: 13 species (2000, 2004) • Persistent Organic Pollutants (2003, 2004)

14. The sulphur model: Developed to describe the transport of sulphur and lead to the Arctic. The purpose is to study large-scale transport and to determine the sources of Arctic pollution. From 1991-2000, the main transport route of air pollution originates in Russia and the highest concentrations are seen in North-eastern Greenland. Highest depositions are seen in Southern Greenland due to higher precipitation rates in this area.

15. COSAM model inter comparison, 1998experience on global scale • COSAM: A Comparison Of The Performance Of Large Scale Models In Simulating Atmospheric Sulphate Aerosols(Cosam) operated under WCRP/WGNE and IGAC/GIM. • Describing in detail each model and its parameterization of processes. • Comparing model-predictions of atmospheric sulphates and associated precursors (e.g. SO2) with regional sulphur budgets as well as with observed concentrations of sulphate, DMS, SO2 and MSA in the troposphere. • Performing tests that will assist in understanding differences in output and how well the processes of boundary layer mixing, vertical convection, chemical/physical transformation and precipitation scavenging are modelled.

16. 11 models participate:

17. Detail description of the different model runs and how the output should be was given. • A database with measurements was established • Each model group had some months to perform the model calculations. • A central person was doing all the post processing of model output in order to unified the results. • All results was presented at a single workshop

18. Three groups: • One group were looking general on models, establish database with measurements, compare with measurements • Second group were looking at budgets • Last group were looking at vertical gradients

19. Comparisons with measurements

20. Vertical profiles

21. Budgets

22. Each group work results in three different papers : • L. A. Barrie, Y. Yi, U. Lohmann, W.R.Leaitch, P. Kasibhatla, G.-J. Roelofs, J. Wilson, F. McGovern, C. Benkovitz, M.A. Meliere, K. Law, J. Prospero, M. Kritz, D.Bergmann, C. Bridgeman, M. Chin, J. Christensen, R. Easter, J. Feichter, A. Jeuken, E. Kjellstrom, D. Koch, C. Land, P. Rasch: A comparison of large scale atmospheric sulphate aerosol models (cosam): overview and highlights. Tellus, 53B, pp 615-645, 2001. • U. Lohmann, W.R. Leaitch, K. Law, L. Barrie, Y. Yi, D. Bergman, C, Bridgeman, M. Chin, J. Christensen, R. Easter, J. Feichter, A. Jeuken, E. Kjellstrom, D. Koch, C. Land, P. Rasch, G.-J Roelof: Vertical distributions of sulphurspecies simulated by large scale atmospheric models in cosam: Comparison with observations. Tellus, 53B, pp 646-672, 2001 • G.J. Roelofs, P. Kasibhatla, L. Barrie, D. Bergmann, C, Bridgeman, M. Chin, J. Christensen, R. Easter, J. Feichter, A. Jeuken, E. Kjellström, D. Koch, C. Land, U. Lohmann, P. Rasch: Analysis of regional budgets of sulfur species modelled for the COSAM exercise. Tellus, 53B, pp 673-694, 2001

23. The Chemistry model: This version includes a comprehensive chemistry module capable of handling several different air pollution problems e.g. deposition of nitrogen to marine systems. Depending on the resolution of the model (the number of nests) it is also possible to calculate deposition to sensitive ecosystems. The chemistry model has been run with one nest for a period of 25 years (50 km resolution) and with two nests for selected periods (1998, 2004).

24. Chemical scheme and emissions: Original chemical scheme: Strand and Hov, 1994; includes 44 species. Application of a modified version with 51 species presented in Flatøy and Hov, 1996. At present 64 species are included of which 4 relate to particles (Frohn, 2003). Emissions: GEIA (1º x 1º) EDGAR (1º x 1º) EMEP (50 km x 50 km) GENEMIS (16.67 km x 16.67 km) DK data (1 km x 1 km)

25. Review/intercomparison on country scale DEHM, 3-d eulerian model, 16.67 km resolution ACDEP, trajectory model

26. Review/intercomparison on regional scale:EMEP-W review/intercomparison Participating models: EMEP REM-Calgrid DEHM CHIMERE MATCH LOTOS MODELS-3, partly Review/intercomparison only by comparison with measurements In general no large differences in model performance of the participating models

27. The Mercury model: Modelling of mercury is a relatively new but very hot research area. During the polar sunrise a strong depletion in mercury air concentrations is observed. Experiments with the model formulation of mercury chemistry show that the observed depletion can be explained by including an additional fast oxidation rate of Hg0 to HgO during the polar sunrise. Main purpose is to study the transport of mercury to the Arctic

28. Chemical scheme and deposition rates Included chemical scheme is the GKSS chemistry (Petersen et al., 1998) Gas phase pollutants: Hg0 , HgO, HgCl2 and particulate Hg 9 aqueous phase pollutants Chemistry depending on O3, SO2, Cl- and Soot. O3 and SO2 from the chemistry version of DEHM. During the polar sunrise in the Arctic an additional fast oxidation rate of Hg0 to HgO is assumed Wet removal rates as for sulphate Dry removal rates for HgO and HgCl2 as for HNO3 and for particulate Hg as for sulphate.

29. Intercomparison Study of Numerical Models for Long-Range Atmospheric Transport of Mercury organised by MSC-E.

30. 7 participating models, all dynamic models

31. Comparisons of chemical schemes • similar set-up (emissions, etc) • shortterm comparisons with measurements • longterm comparisons • depositions • some source/receptor relations • such a intercomparison is important due to less knowledge about atmospheric mercury compared f.ex. to Sulphur-nitrogen-Ox-HC chemistry

32. Stage I: MSC-E Technical Report 2/2001: "Intercomparison Study of Numerical Models for Long-range Atmospheric Transport of Mercury Stage I. Comparison of Chemical Modules for Mercury Transformations in a Cloud/Fog Environment" • Stage II: MSC-E Technical Report 1/2003: "Intercomparison Study of Numerical Models for Long-Range Atmospheric transport of Mercury" • Stage III: MSC-E Technical Report 1/2005: "Intercomparison Study of Numerical Models for Long-Range Atmospheric Transport of Mercury. Stage III. Comparison of modeling results with long-term observations and comparison of calculated items of regional balances." • Plans of Peer-review papers based on the results from each stage

33. The POP-model: The POP model has a larger domain than the other versions of DEHM. It has been developed using -hexachlorocyclohexane (-HCH) as a tracer. -HCH is the major component of the most used insecticide worldwide. Now the model also include PCB’s. The model is run for the years 1991-1998 with yearly emission data linearly interpolated from data for 1990 and 2000. The emissions are evenly distributed throughout the year. Input data also includes ocean concentrations determined from measurements.

34. Calculated concentrations of -HCH:

35. Gas-phase Particle phase

36. POP Model Intercomparison Study organised by MSC-E, 18 models, both dynamic and box models

37. Stage I: MSC-E Technical Report1/2004: "POP Model Intercomparison Study. Stage I. Comparison of Descriptions of Main Processes Determining POP Behaviour in Various Environmental Compartments" • Stage II: MSC-E Intermediate Technical Report 2/2005 "POP Model Intercomparison Study. Stage II. Comparison of Mass Balance Estimates and Sensitivity Studies" (under preparation) • Stage III: Comparison of calculated overall environmental persistence and long-range transport potential for evaluation of new substances (future stage)

38. Conclusion: Model intercomparison is important exercise in order to do a model review Model intercomparison has shown to be important for the development of the DEHM model system. Therefore we participate in many model intercomparisons, as. e.g. MSC-E’s. The COSAM model intercomparison have shown to be a good example of a model intercomparison, because it involved many aspects, and not only comparison with measurements. This is especially important for species as Mercury and POP’s where there is less knowledge, which increase the use of parameterisations.There was a detailed set-up and description of the different model runs, so the modellers could do all runs before a single workshop, where the results were presented and discussed. In principle the intercomparison arranged by MSC-E is quite similar to the COSAM, and therefore a good intercomparison study, but it is a slow process (years), which could be a problem for some modellers.