Stage II of the POP intercomparison study

At Stage II it was agreed to perform the comparison of mass balance estimates and several sensitivity studies with respect to descriptions of basic processes and mass balance estimates.

Programme on Stage II of POP model intercomparison study
PCB-153 is the main pollutant being considered. For PCB-28 and PCB-180, the computational experiments are carried out on the voluntary basis. The file "Physical-chemical properties for Stage II" contains the "reference data sets" (without any changes from previous version of Stage I) and alternative data sets of physical-chemical properties for the considered PCBs. The alternative sets based mainly on the individual data sets of CliMoChem and DEHM-POP models are proposed to perform sensitivity studies for models for which "reference data sets" coincide with its own sets of physical-chemical properties.

What is expected to be done within Stage II is presented below in more detail.

1. Within sensitivity study with respect to description of basic processes all participants are supposed to do the following:

To perform calculation experiments formulated at Stage I with the use of "reference data set" or physical-chemical data set of the individual model (or alternative data set). Please perform these experiments on the basis of that physical-chemical data set, which you've not yet used at Stage I. Input data and templates for presenting results of these experiments can be found in the file "Templates for Stage I".

To carry out additional experiments on wet deposition process for some precipitation episodes and comparison of their results with measurements. Input data for these experiments prepared by Gerhard Petersen. This additional experiment is supposed to be begun with computation of B[a]P wet deposition, which is predominately in the particulate phase in the atmosphere. In future it is possible to extend the study to the consideration of PCB congeners, which can be in the gas phase as well as associated with particles.

2. Within comparison study of mass balance estimates (annual and monthly means) obtained on the basis of physical-chemical data set of the individual model (or alternative data set) the calculation of the following parameters should be performed:

PCB mass in environmental compartments (atmosphere, soil, water, vegetation);
mass of PCB degraded in these compartments;
mass flow of PCB transported in/out of the specified domain: inflow and outflow (for each transport media as optional);
mass flow of PCB transported from one compartment to another in both directions (dry and wet deposition, gaseous exchange);
PCB concentrations at each interface;
spatial distributions of PCB depositions and concentrations in different compartments with zero initial concentrations (optional);
spatial distributions of PCB depositions and concentrations in different compartments with initial concentrations of pollutants in media or taking into account historical emissions (optional, for comparison of calculated and measured data).

Templates for the results of these experiments to be filled in by the participants in the course of Stage II calculations are presented in the file "Templates for Stage II". It contains descriptions of computational experiments of Stage II (see list "Stage II experiments"); comments to input data for these experiments and description of calculation domain (see list "Input data"); tables which should be filled in for specification of some input data used individually by each model (see list "Specification") and a number of tabular templates on each experiment to be filled in (see lists: "Mass balance", "Degradation", "Inflow-outflow", "Intermedia transport", "Spatial distribution 1" and "Spatial distribution 2").

Input data for this stage experiments include the following information:
numerical data on spatial distribution of PCB-153, PCB-28 and PCB-180 emissions kindly presented by Sunling Gong and Ping Huang;
data on initial concentrations of pollutants in media calculated by MSC-E;
land cover data,
Leaf Area Index data,
data on organic matter content in the soil,
data on total percentage of land, water and vegetation areas.


All these input data are available by request.

3. Within sensitivity study with respect to mass balance estimates, the calculation experiments mentioned above are carried out with the use of "reference data sets" in addition to those mentioned in item 2.

Please fill in the tabular templates with your calculation results and send them back to us by the end of June 2004.
Please provide us also with general description of mass balance approach used in your model at the end of the list "Specification" and make brief comments on each calculation experiment of Stage II at the end of each tabular templates with your results.

All modellers are welcome!