Ice cores are commonly used to reconstruct the chemical composition of historical deposition, and there is great interest to link the concentrations of various trace components in the kc with their concentrations in the atmosphere at the time of deposition Therefore it is important to understand the atmosphere/snow transfer mechanisms for the different spccies. In mixed phase clouds, i.e. clouds containing icc crystals, it is assumed that supercooled cloud droplets arc first fonrjed. After ice nucleation, ice crystals grow by water vapour deposition at the expense of the supercooled cloud droplets (Wegener-Bcrgcron-Fintleiswi mechanism) and/or by direct accretion of cloud droplets (called rinung) onto the crystal’s surface. The first mechanism is often the dominant physical process but insignificant wiih respect to the removal or transfer of pollutants resulting in very dean ke crystals. The latter mechanism determines to a great extent the chemical composition of the kc crystals in polluting them with activated aerosol panicles. However, the degree of riming depends on a variety of parameters, such as cloud droplet size, snow crystal size and snow crystal settling velocity.
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- Air/Snow Transfer Studies at the High-Alpine Site Jungfraujoch, Switzerland
- Springer Berlin Heidelberg