A SIMPLE-MODEL TO ESTIMATE ATMOSPHERIC CONCENTRATIONS OF AEROSOL CHEMICAL-SPECIES BASED ON SNOW CORE CHEMISTRY AT SUMMIT, GREENLAND

A simple model is presented to estimate atmospheric concentrations of chemical species that exist primarily as aerosols based on snow core/i ce core chemistry at Summit, Greenland. The model considers the proces ses of snow, fog, and dry deposition. The deposition parameters for ea ch of the processes are estimated for S0(4)(2-) and Ca2+ and are based on experiments conducted during the 1993 and 1994 summer field season s. The seasonal mean atmospheric concentrations are estimated based on the deposition parameters and snow cores obtained during the field se asons. The ratios of the estimated seasonal mean airborne concentratio n divided by the measured mean concentration ((C) over bar(a,est)/(C) over bar(a,meas)) for SO42- over the 1993 and 1994 field seasons are 0 .85 and 0.95, respectively. The (C) over bar(a,est)/(C) over bar(a,mea s) Ca2+ are 0.45 and 0.90 for the 1993 and 1994 field seasons. The unc ertainties in the estimated atmospheric concentrations range from 30% to 40% and are due to variability in the input parameters. The model e stimates the seasonal mean atmospheric SO42- and Ca2+ concentrations t o within 15% and 55%, respectively. Although the model is not directly applied to ice cores, the application of the model to ice core chemic al signals is briefly discussed.