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The EMEP Unified model

The EMEP Unified model. Eric van der Swaluw (RIVM), Addo van Pul (RIVM), Jerzy Bartnicki (EMEP) and Hilde Fagerli (EMEP). Background of the presenter . Preparation of assessment of the Comprehensive Atmospheric Monitoring Programme (CAMP) for the INPUT meeting of OSPAR in February 2009

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The EMEP Unified model

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  1. The EMEP Unified model Eric van der Swaluw (RIVM), Addo van Pul (RIVM), Jerzy Bartnicki (EMEP) and Hilde Fagerli (EMEP)

  2. Background of the presenter • Preparation of assessment of the Comprehensive Atmospheric Monitoring Programme (CAMP) for the INPUT meeting of OSPAR in February 2009 • The CAMP assessment panel used model results from EMEP unified model of atmospheric nitrogen deposition over the OSPAR regions over the period 1995-2006 • Experience with several numerical models since 1997: computational fluid dynamics (CFD), coupled atmosphere-ocean (climate) models and the transport model LOTOS-EUROS

  3. Deposition of nitrogen from 1998-2006 Comparison between trends in EMEP simulations and observations of wet deposition at CAMP monitoring stations Total nitrogen deposition in 2006 (in units of mg N / m2)

  4. Comparison between atmospheric deposition(EMEP) and riverine input(RID) • Total nitrogen inputs into the Greater North Sea • RID contributes ~70% of the total nitrogen input • Large uncertainties in RID data • Total nitrogen input into the Arctic waters • Atmospheric deposition accounts for ~90%

  5. Structure and models of EMEP The EMEP programme • Co-operative programme for monitoring and evaluation of the long-range transmission of Air Pollutants in Europe EMEP/MSC-W • Meteorological Synthesizing Centre West (Norway) • Transport models of acidifying and eutrophying components (S, N), ground level ozone (O3) and particulate matter (PM10 and PM2.5) EMEP/MSC-E • Meteorological Synthesizing Centre East (Russia) • Transport models of heavy metals (Pb, Cd and Hg) and a selected number of persistent organic pollutants (PCB, PAH, HCB, PCDDS/Fs, g-HCH)

  6. continued CCC • Chemical Coordinating Centre (Norway) • The co-ordination and intercalibration of chemical air quality and precipitation measurements

  7. Main goal of a chemical transport model • The main goal of the EMEP unified transport model is to model the transport and deposition of acidifying and eutrophying compounds as well as photo-oxidants over the domain of the model

  8. The grid of the model Model grid size equals 170x133 20 sigma levels reaching up to 100hPa 10 layers below 2 km

  9. Information from grid cell • In ‘reality’ the concentration of the pollutant might not be constant in the grid cell • In simulations you assume however that the concentration of the pollutant isconstant throughout the cell volume

  10. Emissions • Emissions are distributed over the horizontal and vertical grid (emissions are reported by countries to EMEP) • Emissions for nitrogen include ship traffic (next slide) • A division in sectors can be made for the emissions (for example agriculture, road transport, …)

  11. Continued • Contribution international ship traffic taken into account • NO2 emission for ship traffic in 2004 • Unit: tone N/year

  12. Transport • Transport is calculated by using velocities from 3-hourly resolution meteorological data (PARLAM-PS Numerical Weather Prediction model) • Linear interpolation is used for time steps in the model which are smaller than 3 hours • Apart from advection by wind velocities, there is also diffusive transport resulting from turbulence

  13. Chemistry • Sulphur and nitrogen chemistry is included in the model • Concentrations of 71 species are computed in the model • The sulphur and nitrogen chemistry is coupled to the photo-chemistry

  14. Dry deposition • Dry deposition occurs continuously via turbulent eddies • For the total deposition the most important contribution is from dry deposition • The efficiency of dry deposition is determined by the particular land-surface (for example grasslands, water, ice …)

  15. Wet deposition • Wet deposition is very efficient but is not occurring continuously (6%-7% in the Netherlands) • Wet scavenging in the cloud and below the cloud are taken into account • Meteorological data is used to determine when and where precipitation occurs on the model grid

  16. Overview Source Transport & Chemistry Sinks

  17. Uncertainties of the model • EMEP model data is continuously being validated • Comparison between model results and European monitoring data: underestimation of 20% (40%) for reduced (oxidized) nitrogen wet deposition • For OSPAR wet deposition measurements have been compared with model results and the uncertainty of the model is in between 30% and 50%

  18. Continued • Validation model results and wet deposition measurements from monitoring stations near coastal regions • Units: mg N / m2

  19. And the result is … One can choose to study time series in whatever region one likes as long as it is resolved by the model grid! Total nitrogen deposition in 2006 (in units of mg N / m2)

  20. Total nitrogen deposition over period from 1995-2006 for the North Sea

  21. Summary on the model grid • The standard resolution of the model is 50 km • The model can be run in the resolution for which meteorology is available • The model is suitable now to run resolutions of 25km and 10 km for Europe • Higher resolution is possible but not regularly done within EMEP

  22. Coverage in time • CAMP assessment was covered for nitrogen from 1995-2006 • In principle one can do longer time-series BUT one needs meteorological data and emission data for these years! • Time step in the model is of the order of minutes so in principle data can be obtained on the timescale of minutes or larger timescales

  23. Comparison Lotos-Euros model and wet deposition measurements at De Bilt (KNMI, The Netherlands) van der Swaluw et al. (in preparation) Time series of months instead of years!

  24. Are episodic rain events covered by the EMEP model? • Meteorological input: 3-hourly meteorological data from the PARLAM-PS Numerical Weather Prediction model • Yes if rain events of interest are larger than 3 hours • If rain events of interest are smaller than 3 hours, the ‘real amount of precipitation’ of a rain event is smoothed over 3 hours

  25. Summary • Time scales larger than ~ 3 hours can be resolved • Length scales larger than 10 km can be resolved • Finer resolutions are possible if necessary: we could work on this in collaboration with EMEP centers • Long time series (50 years) are in principle possible but the creation of corresponding meteo-data would be time consuming and not easy

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