Fog deposition on a coniferous forest in The Netherlands

Fog deposition in December 1992 and February 1993 (two periods of several days in which fog occurred) was monitored at the location Speulderbos in The Netherlands. Fog droplet deposition was measured with eddy correlation and samples of fog water were taken with a string collector. At the same time, throughfall deposition was measured and throughfall water was sampled. The occult (fog/cloud) deposition during these periods was 3.4 and 2.0 mg m−2s−1 respectively. Throughfall fluxes measured during these periods were a factor of three higher. The contribution of occult deposition to the total acid deposition to forests in The Netherlands is estimated to be about 5%. A clear relationship between the friction velocity u* and turbulent deposition velocity vt of fog droplets could be derived. The measured turbulent deposition velocity for fog is half the deposition velocity for impulse vm.