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United States Department of Agriculture

Agricultural Research Service

Title: 3-D Characterization of Snow Crystals As An Aid to Remote Sensing of Snow Water Equivalent

item Rango, Albert
item Wergin, William
item Erbe, Eric

Submitted to: Application Of Remote Sensing In Hydrology International Workshop
Publication Type: Proceedings
Publication Acceptance Date: September 30, 1997
Publication Date: N/A

Technical Abstract: Snow water equivalent has been estimated using passive microwave satellite data but the microwave algorithms have not been generally applicable in part because of the complexity of the snow structure. Better ways of characterizing the snow crystal size and shape and bonds between crystals are needed. The two dimensional shapes of snow crystals have been previously studied and photographed with light microscopes and cameras. Past investigators have been hampered by sublimation and melting of the snow crystal sample and by the limited resolution of the instruments. Snow samples from Maryland, West Virginia, Colorado, Wyoming, and Alaska have been examined with low temperature scanning electron microscope (SEM) to produce startling new images of snow crystals. Low temperature SEM avoids problems with sublimation melting, provides extreme magnification capability, and allows quantitative measurements of snow crystal size and shape with the assistance of 3-D or stereo imaging. The 3-D representations show in stereo several different types of newly fallen or precipitated snow crystals, numerous examples of crystals in different stages of metamorphism from natural snowpacks, and algae and bacterial forms present in a melting snowpack. The techniques for sampling, storing, and transporting snow crystals to the SEM facility are simple and easy to use.

Last Modified: 4/19/2015
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