Evaluation of PM surface concentrations simulated by Version 1 of NASA's MERRA Aerosol Reanalysis over Europe

This article evaluates the concentrations of particulate matter (PM) and some of its chemical speciation such as sulfate, organic carbon, black carbon and sea salt particles simulated at the surface by Version 1 of the Aerosol Reanalysis of NASA's Modern-Era Retrospective Analysis for Research and Application (MERRAero) over Europe. Measurement data from the European Monitoring and Evaluation Programme database were used. The concentrations of coarse PM (PM₁₀), fine PM (PM_2.5), sulfate and black carbon particles are overall well simulated, despite a slight and consistent overestimation of PM₁₀ concentration, and a slight and consistent underestimation of PM_2.5 and sulfate concentrations throughout most of the year. The concentration of organic carbon was largely underestimated, especially in winter, caused by two specific monitoring stations in Italy, resulting in an overall poor performance for this particular species. After removing these two stations from the sample, the evaluation of OC substantially improved but an underestimation in winter remained. Carbon emissions originating from anthropogenic sources, such as residential wood burning in winter, unresolved by MERRAero provide a plausible explanation for this discrepancy.. The evaluation of PM_2.5, sulfate and organic carbon concentrations improved during the summer. The concentration of fine sea salt particles was consistently and largely overestimated, but contributes relatively little to total PM_2.5 concentration.