Аннотация:Eddy correlation measurements of participate sulfur fluxes at the 1981 and 1982 Dry Deposition Intercomparison Experiments indicate a strong diurnal variation in deposition velocity (downward flux divided by concentration, at a height near 6 m). Most of the run‐to‐run variability for data collection periods of 30 min seems to be due to unwanted sensor noise. Systematic changes of fluxes wth height due to possible advection from strong point sources of sulfur can occur but should be quite small. A parameterization for deposition velocity is derived in terms of friction velocity u * and the Obukhov stability length scale L . When the parameterization is applied in conjunction with nearly continuous measurements of mean micrometeorological variables such as wind speed and temperature difference, the resulting long‐term mean deposition velocity found is 0.22±0.06 cm/s with a variation greater than ±50% from day to day, depending on local atmospheric conditions. Peak deposition velocities greater than 0.5 cm/s occur on windy afternoons. Such values are considerably greater than suggested from wind‐tunnel and theoretical investigations, but are similar to past results obtained by use of the same techniques over lush vegetation. Boundary layer convective motions that increase wind gustiness near the surface seem to increase particle deposition velocities considerably. Relatively small deposition velocities are found in neutral and stable atmospheric conditions or over surfaces that lack complex fine structure.
