9725682 Rose This proposal is aimed at the investigation of the first week or so of interaction between volcanic clouds and the atmosphere, when silicates are still present or maybe even dominant. We will use data jointly obtained from two satellite detectors: a) a two band infrared detection system that is aboard many satellites and which retrieves data on the size and masses of silicate particles, and b) an ultraviolet detector (TOMS), which is capable of measuring SO2 and can also provide data on silicates. Our research foci are to: 1) investigate the shape of volcanic particles with long (>2 hrs) atmospheric residence; 2) study the occurrences of anomalous distal fallout (ADF), where fallout of fine ash occurs in unusual thicknesses very far from the volcano after tens of hours in the atmosphere; and 3) investigate the chemical interaction of irregular volcanic silicates with gases in the volcanic cloud, including the wettability of the ash and the adsorption of SO2 and other gases on ash surfaces. The primary goal of this research is to produce a quantitative shape index for use in calculating the fallout rates of small particles. The proposed research is driven by the issue of aircraft hazards of volcanic clouds and by the need to understand the potential hazards of distal fallout based explaining past events in the geologic record.
