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  • Author or Editor: Edmond W. Holroyd III x
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Edmond W. Holroyd III

Abstract

A 2D-C probe was mounted on the front of a truck for operation in a horizontal orientation, as on an aircraft, and also in a vertical orientation using an aspirator. A snowstorm with calm conditions was sampled by alternatively driving the truck through the snow, using a calibrated anemometer to control the strobe rate, and then sampling with an aspirator while parked. The concentration measurements using an aspirator were about 2.4 times larger than those using the standard aircraft orientation mode. There was little size dependence in this factor for the dendrite/aggregate snow sampled. It is not yet known what causes the aspirator concentration measurements to be larger than those from other techniques.

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Edmond W. Holroyd III

Abstract

A technique has been designed that uses observable properties of images from a 2D-C optical array probe (size, linearity, area, perimeter, and image density) to classify unsymmetrical ice particles into nine habit classes. Concentrations are calculated by requiring that the center of each accepted particle appear to be within the field of view of the probe. Once the size and habit are estimated, a generic mass and terminal velocity can be assigned to each particle to calculate its contribution to ice water content and to precipitation rate. Examples are given to indicate the value of a habit classifier in analyzing the structure of storms, showers, orographic clouds, and seeded clouds. Though the techniques work well for most natural snowfalls, some examples of imperfections are given to remind the analyst to look at the images and to understand how the classifer will treat them.

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