Atmospheric modelling activities inside the Danish AMAP program Jesper H. Christensen NERI-ATMI, Frederiksborgvej Roskilde

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 Developed since In the beginning only for Sulphur, later Lead and now also with a full photochemical scheme and Mercury.

The Danish Eulerian Hemispheric Model in 1. Phase of AMAP Direct coupling to ECMWF data, no MM5 meteorological preprocessor Simplified linear sulphur chemistry

The Danish Eulerian Hemispheric Model (DEHM) System

MM5 model Hydrostatisk version (version 2) 150 km resolution at 60° N, 50 km for nested domain 97x97 horizontal grid-points (for mother domain and 100x100 horizontal gridpoints for nested domain) and 20 vertical layers Mixed Phase (Reisner) explicit moisture Betts-Miller cumulus parametrization MRF boundary layer parametrization with 5 layer soil model Cloud-radiation scheme

Input data: Met data from ECMWF, 2.5°x2.5° lat-lon, 12 hour resolution, 21 years data from 1979 to 2000 Output every 3 hours Only run for 1990 to 2000 for hemispheric domain and for 1995 and 1998 to 2000 for Europe (50 km) 1 month for Greenland (50 km) as demonstration

The Danish Eulerian Hemispheric Model Full three dimensional advection-diffusion equations 150 km grid resolution (Mother domain) 20 vertical levels up to 16 km Dry deposition based on the resistance method with 8 different surfaces Wet deposition based on scavenging coefficients Numerical methods: Horizontal advection: Accurate Space Derivatives with non- periodic boundary conditions and 2-way nesting capabilities Vertical advection: Finite Elements Diffusion: Finite Elements

Nested version of DEHM a demonstration with the simplified sulphur version 150 km resolution50 km resolution

The monthly mean concentrations for SO X 150 km resolution50 km resolution

Mercury version of DEHM Mercury model with GKSS chemistry Gas phase pollutants: Hg 0, HgO, HgCl 2 and particulate Hg 9 aqueous phase pollutants Chemistry depending on O 3, SO 2, Cl - and Soot During the polar sunrise in the Arctic an additional fast oxidation rate of Hg 0 to HgO is assumed Wet removal rates for all aqueous phase pollutants as for Sulphate Dry deposition velocity for HgO and HgCl 2 as for HNO 3 and for particulate Hg as for Sulphate From Petersen et al. (1998 )

Examples of results with mercury model

Photochemical version of DEHM Pollutants: 54 species, more than 110 chemical reactions, chemistry scheme similar to the EMEP oxidant model Emissions: Global GEIA emissions of anthropogenic emissions of SO X and NO X, NO X from lightning and soil and Isoprene form vegetation, all on 1°x 1° global EDGAR inventory on 1°x 1° for anthropogenic hydrocarbons SO X and NO X for Europe from EMEP Has been run for whole 1998

Purpose with the photochemical version Improvement of the parameterization of the chemistry compared to the simple sulfur model Provided necessary input concentrations for the Mercury model Be a useful contribution for the understanding of the atmospheric chemistry in the Arctic, especially during the Polar Sunrise in connection with field measurements Provided necessary hemispheric background concentrations for the regional models, e.g. for Europe

Results from chemical version NO 2 mean concentrations

Ozone mean concentrations

Example of ozone transport into the North Atlantic

Some validations

Ozone in the Arctic

Ongoing activities and future work Continuing the work with parameterization of background chemistry, coupling with aqueous chemistry Nested model calculations for Europe Improve parameterization of Arctic chemistry, coupling with GOME measurement of BrO, coupled to measurements in the Arctic in order to understand the spatial and temporal distribution of the depletion From Richter et al. (1997)

ACKNOWLEDGEMENTS 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