Intercomparison study

Ten years ago in 1994 the Bureau of the EMEP Steering Body suggested to set up an Advisory scientific group to assist MSC-E in the development of HM and POP model approaches. Scientists from the Netherlands, Germany, Sweden, Norway and Bulgaria were involved in this group from the beginning. Later modelers from the USA, Canada, UK, Switzerland and Denmark have joined to this group. The main goal of this community is to improve our knowledge about physical-chemical properties and environmental transport of toxic substances. Usually every year MSC-E organizes a meeting in Moscow to discus a progress in modeling. In 1995-1997 main attention was given to lead model intercomparison, in 1998-2000 to cadmium, then to mercury. At present we continue mercury model exercises and started comparison of POP model approaches. Results of the model intercomparison are presented jointly to the SB and TFMM and published in scientific literature. Mercury chemistry transformation scheme developed by Dr. Petersen was adapted to EMEP/MSCE-HM model. This form of cooperation is of mutual interest and allows MSC-E and national experts to compare different approaches and to use best available information.

POP multicompartment models

Environmental pollution by POPs is now in the centre of attention of international community. A number of international binding instruments on elimination, restriction, and reduction of POPs production, usage, and emissions have been developed. Among those are Protocol on POPs to Convention on LRTAP and Stockholm Global Convention on POPs. Many international organizations have included POPs in their work programs (WMO, UNEP, CLRTAP, OECD, HELCOM, AMAP, EUROTRAC, OSPAR, and others). International regulatory activities on POPs include, in particular:

evaluation of long-range transport, accumulation and deposition of POPs in compliance with existing obligations;
elaboration of effect-oriented approach for POPs (risk assessment and risk management);
evaluation of new substances to be included in the regulatory activity.

For the assessment of POPs contamination both on regional and global levels a complex monitoring/modelling approach seems to be reasonable. Since there are not so many measurement data on POPs concentrations in various environmental compartments, modeling plays a significant role in the assessment of POPs contamination.

In developing model tools of contamination assessment one has to take into account that the behaviour of POPs in the environment is characterized, in particular, by their ability to accumulate in different environmental compartments with possible re-volatilisation to the atmosphere. Hence, evaluation of environmental pollution by POPs requires application of multimedia models. At present there exist a lot of different types of models describing POPs cycling in the environment taking into account intermedia exchange processes. The complexity of such models, in accordance to their purposes, vary from simple box models describing distribution of a pollutant in question between various environmental media to spatially resolved dynamic models taking into account peculiarities of the real environment (such as meteorological and geophysical information).

To obtain comparable results the harmonization of model output is required. The necessity of intercomparison of different types of POPs transport models was included to the recommendations of the WMO/UNEP/EMEP Workshop on modeling of atmospheric transport and deposition of POPs and HMs, Geneva (Switzerland), November 1999. Later on, the work of intercomparison of POPs long-range transport models was included to the EMEP work-programme. The recent OECD/UNEP Workshop on the use of multimedia models for estimating overall persistence and long-range transport, Ottawa (Canada), October 2001 also marked a necessity of intercomparison study of POPs multimedia models of different complexity.

More detailed information about POP model intercomparison are available here.

HM transport models

The heavy metal long-range transport model intercomparison has been started in accordance with the decision of the 18th session of the Steering Body to EMEP (EB.AIR/GE.1/24,1994). The first stage intended for lead model intercomparison was carried out in 1996 [Sofiev et al., 1996]. Following the recommendation of the experts of the Advisory Group, approved by the 15th session of the Executive Body (EB.AIR/1996/6) cadmium model intercomparison was carried out in 1998 [Gusev et al., 2000].

In accordance with the recommendations of EMEP/WMO workshop (Moscow, 1996) and Advisory Group (Moscow, 1999) MSC-E has organized an intercomparison study for mercury models. National and international scientific groups and experts interested in this study have been invited to participate in the study. More detailed information about intercomparison for mercury models is devoted here.