Dry deposition of ozone: some measurements ofdeposition velocity and of vertical profiles to 100 metres

Deposition velocities for O₃ to grassland have been measured by the gradient method. Values range from 0.08 to 0.91 cms⁻¹ and are shown to be influenced most substantially by changes in surface conditions. O₃ deposition is inhibited by the presence of snow or moisture at the surface and tends to decrease as the afternoon progresses. Vertical profiles of O₃ and temperature to 100 m height are indicative of surface depletion of O₃ by dry deposition and a diminution of concentration at ground-level due to inhibition of vertical mixing from aloft during periods of atmospheric stability. Dry deposition fluxes are shown to be adequate to account for the diurnal variation of O₃ observed at ground-level in rural areas during summer anticyclonic conditions.