Results

The results of the model run using ANU-CTM with ECMWF wind field data for 1993 are presented in Figures 3 and 4. Figure 3 presents individual concentration estimates at times throughout the year whereas Figure 4, an animation, contains all the model results.

Both figures show an isosurface approximately representing the point at which the tracer, in this case a radioactive gas, in an air parcel has been diluted down to 25% of its original concentration at the point of release in Java. This is level of dilution is defined as providing a high level of risk.

The isosurface is three dimensional and is determined by the transport of numerous individual air parcels. Below this isosurface concentrations will generally be higher. Beyond this isosurface concentrations will generally be lower.

Occasionally high concentrations can remain in air parcels transported over great distances. Eventually the release of a trace gas mixes throughout the global atmosphere while slowly being removed by rain, contact with the land surface, plants and the ocean and through chemical transformations in the atmosphere.

Image Series...

Figure 3 - Shows the 25% dilution isosurface (regions at high risk) for every 15 days during the one year model run. Below this isosurface air parcels contain a concentration of tracer that is greater than 25% of that at the point of release.

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Figure 4 - Shows the 25% dilution isosurface (regions at high risk) as an animation for every day during the one year model run. Below this isosurface air parcels contain a concentration of tracer that is approximately 25% greater than of that at the point of release.

Discussion ...

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