Assessment of Ice Particle Growth and Scavenging Processes at Summit, Greenland

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This project will make observations of cloud droplets and snow crystal replicas at the GISP-II coring site in Greenland in order to assess the importance of ice particle riming on chemical wet deposition and aerosol scavenging at the Summit site during the summer of 1990. Aerosol scavenging is a complex process which takes different forms within clouds and below coulds, and also depends strongly on the cloud droplet distribution spectrum, focusses on the collision efficiencies between ice particles and cloud droplets (the riming process), and the subsquent scavenging efficiencies and precipitation rates. Atmospheric aerosol particles scavenged by ice crystal growth form a part of the chemical record preserved in the Greenland ice sheet, and form a time series in the observations in an ice core. This record has historically been interpreted as a representation of the composition of the atmosphere at the time of deposition, and a variation of the particle content along the core has been interpeted as a corresponding variation in the composition of the atmosphere. The assumption that a one-to-one relationship exists, or even that it is linear, is not well established at this time. This project will help establish a firmer basis for these relationships.