Aerosol dry deposition measured with eddy-covariance technique at Wasa and Aboa, DronningMaud Land, Antarctica

Interpretation of ice-core records in terms of changes in atmospheric concentrations requires understanding of the various parameters within air–snow transfer functions. the dry-deposition velocity is one of these parameters, dependent on local meteorological conditions and thereby also affected by climate changes. We have determined aerosol dry-deposition velocities by measurements of aerosol particle-number concentration and the vertical wind component with an eddy-covariance system close to the Swedish and Finnish research stations Wasa and Aboa in Dronning Maud Land, Antarctica. Measurements were performed over a smooth, snow-covered area and over moderately rough, rocky ground during 4 and 19 days, respectively, in January 2000. the median dry-deposition velocity determined 5.25 mabove the surface was 0.33 and 0.80 cm s–1, respectively. the large difference between the two sites was mainly due to the stratification of the surface boundary layer, the surface albedo and the surface roughness height. the dry-deposition number fluxes were dominated by the particle-size modes defined as ultrafine and Aitken, withmean diameters around 14 and 42 nm, respectively. A larger dry-deposition velocity, owing to stronger Brownian diffusion, for the smaller ultrafine mode was verified by the measurements.