Progress Report. Intercomparison Study of Numerical Models for Long-Range Atmospheric Transport of Mercury
Stage II. Comparison of modelling results with observations obtained during short-term measuring campaigns

MSC-E Technical Note 10/2002

R.S.Artz, R.O.Bullock, J.Christensen, M.Cohen, A.Dastoor, D.Davignon, R.R.Draxler, R.Ebinghaus, I.Ilyin, J.Munthe, G.Petersen, A.Ryaboshapko, D.Syrakov

ABSTRACT

The mercury model intercomparison study was launched in 1999. The mercury intercomparison study is focused on:
- an evaluation of parameterizations of the main physical-chemical processes of mercury transformations in the gaseous and the liquid phase;
- a comparison of modeling results with measurements obtained from both short-term campaigns and from the EMEP monitoring network and other international and national programs;
- a comparison of the main features of long-range transport of different mercury forms.

The program of the mercury model intercomparison study envisages four stages:

Stage I. Comparison of modules for physico-chemical transformations of mercury species in a cloud/fog environment with prescribed initial mercury concentrations in ambient air and other physical and chemical parameters relevant for atmospheric mercury transformations.

Stage II. Comparison of model results with observations during 1-2 weeks episodes. Hourly and daily averages and event based averages of mercury concentrations in air, obtained from the joint Swedish/Canadian/German field campaign TRANSECT 1995 and from the European Union Environment & Climate project Mercury Species Over Europe (MOE-1999) will be used.

Stage III. Comparison of model results with observed monthly and annual means of mercury concentrations in air and precipitation and deposition fluxes available from European monitoring stations in 1998.

Stage IV. Comparison of model predicted atmospheric budgets of mercury species in the entire EMEP domain and for selected European countries (UK, Poland and Italy), including dry and wet deposition within and outside the area of the countries.

The first stage of the intercomparison study was started in 1999 and finished in 2001. In addition to the MSC-East four scientific groups from Germany, Sweden and the USA took part in the study. The results were presented in [Ryaboshapko et al,. 2001] and published in "Atmospheric Environment" Journal (v. 36, No 24, 2002, 3881-3898).

The second stage started in 2001 is focused on comparison of modeled and observational results. The observations were performed at five measurement sites in Europe during two short-term campaigns in 1995 and 1999. In the first case main attention was paid to the mercury elemental form. In 1999 reactive gaseous and aerosol mercury were measured in addition to the elemental form. To discuss the program of the second stage a workshop was organized in Moscow in February 2002. The participants discussed the volume of calculations, methods of their statistical processing, and formats of reporting data. All details were agreed and accepted as a working plan.

Seven scientific groups involved in atmospheric mercury modeling participated in the second stage. They represent all the most advanced scientific and operational mercury models of regional and global types known by the moment. They are:

- GKSS-Forschungszentrum Geesthacht GmbH (Germany), the European mercury version of the Acid Deposition and Oxidants Model (ADOM).
- U.S. Environmental Protection Agency (USA), the Community Multi-Scale Air Quality (CMAQ) model.
- Environment Canada (Canada), Global/Regional Atmospheric Heavy Metals Model (GRAHM).
- National Ocean and Atmosphere Administration (USA), Hybrid Single Particle Lagrangian Integrated Trajectory model, version 4 (HYSPLIT_4)
- National Institute of Meteorology and Hydrology (Bulgaria), Eluarian Model for Air Pollution (EMAP)
- National Environmental Research Institute (Denmark), Danish Euliarian Hemispheric Model (DEHM)
- Meteorological Synthesizing Centre-East (Russia), MSCE Heavy Metal model (MSCE-HM).

The second stage of the mercury model intercomparison campaign should help to answer two very important questions:
- can the current atmospheric mercury models of regional and global levels reproduce mean values and short-term (hours) peaks of total gaseous mercury concentrations observed in Central Europe at monitoring stations?
- can the models catch mean values and variations of concentration of particulate mercury and reactive gaseous mercury compounds?