Estimating critical load exceedance by combining the EMEP model with data from measurement stations.

We combine EMEP modelled data on acid pollutants with measurements at a network of monitoring stations. The aim is to improve the estimation of critical load exceedance by accounting for the variability in deposition within an EMEP grid square. We also estimate the bias and random error in the EMEP model. We use a statistical model which regards both EMEP predictions and measurements as observations of an underlying true deposition. By making some reasonable assumptions about the form of this underlying truth, and about the errors in the EMEP predictions, we can obtain both interesting estimates of the EMEP errors, and better estimates of critical load exceedance.