Atmospheric Transport Model Evaluation Study

Transport and dispersion was evaluated without any form of tuning by comparing a simulation of the ETEX-1 release to the official measurements of surface concentration. To facilitate comparisons with models evaluated during ATMES 11 (Atmospheric Transport Model Evaluation Study) an identical statistical methodology was employed (Mosca et al. 1998). Background values were subtracted so that only the pure tracer concentration was used. Measurements of zero concentration (concentrations below the background level) were included in time series to the extent that they lay between two non-zero measurements or within two before or two after a non-zero measurement. Hereby, spurious correlations between predicted and measured zero-values far away from the plume track are reduced. 

To evaluate the deposition routines a simulation of the Chernobyl accident was carried out and compared to measurements of total deposited Cesium 137 (Cs-137). The measurements were extracted from the Radioactivity Environmental Monitoring database at the Joint Research Centre, Ispra, Italy (http //rem.jrc.cec.eu.int/). The comparison date was chosen to be 1 May 1986 at 12 00 UTC, since at this time the greatest number of measurements was available. Statistical measures were calculated following the recommendations of the Atmospheric Transport Model Evaluation Study (ATMES) final report (Klug et al. 1992). 

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