Simulation of the atmospheric concentrations of 210Pb and 7Be and comparison with daily observations at three surface sites

The atmospheric transport of Pb-210 and Be-7 is simulated by the Laboratoire de Meteorologie Dynamique general circulation model, LMDz, driven by ECMWF reanalyses. Daily averaged concentrations collected at three surface stations are compared with numerical results for a 1 year (2004) global simulation. The model, with a resolution of 3.75 degrees x 2.5 degrees and 19 levels, succeeds in reproducing daily variations of Pb-210 and Be-7 concentrations. Figures of merit in time (FMT), quantifying the overlapping of the predicted and observed time series over each month, range from 55% to 70%. Sensitivity studies as well as the analysis of numerical signals allow determining the main physical atmospheric processes characterizing the stations on a daily basis. Concentrations of Pb-210 at the three stations are particularly sensitive to scavenging in convective updrafts. (c) 2007 Elsevier Ltd. All rights reserved.