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United States Department of Agriculture

Agricultural Research Service

Title: Collecting, Shipping, Storing and Imaging Snow Crystals and Ice Grains with Low-Temperature Scanning Electron Microscopy

Authors
item Erbe, Eric
item Rango, Albert
item Foster, James - NASA GODDARD FLIGHT CTR
item Josberger, Edward - USGS TACOMA, WA
item Pooley, Christopher
item Wergin, William

Submitted to: Microscopy Research and Technique
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 27, 2003
Publication Date: September 1, 2003
Citation: ERBE, E.F., RANGO, A., FOSTER, J., JOSBERGER, E.G., POOLEY, C.D., WERGIN, W.P. COLLECTING, SHIPPING, STORING AND IMAGING SNOW CRYSTALS AND ICE GRAINS WITH LOW-TEMPERATURE SCANNING ELECTRON MICROSCOPY. MICROSCOPY RESEARCH AND TECHNIQUE. 2003. V. 62(1). P. 19-32.

Interpretive Summary: Based on results of low temperature scanning electron microscope (LTSEM) imaging of frozen insect and plant samples, it seemed there was a potential for imaging snow and ice crystals. Other investigators had tried to use LTSEM for this purpose but failed because of poor field and sample handling techniques. Appropriate techniques for extracting samples, storing them in liquid nitrogen coolers, shipping and microscope handling techniques have now been carefully worked out so that, with minimal training, new investigators can duplicate the techniques. Comparison with conventional light microscopy shows the LTSEM crystal samples are preserved and the resulting products have superior resolution, depth of field and three-dimensional capabilities over the light microscopy approach. These techniques will be most valuable to snow field researchers requiring microscopic detail for calibrating remote sensing approaches for determining snow properties.

Technical Abstract: Methods to collect, transport and store samples of snow and ice have been developed that enable detailed observations of these samples with a technique known as low temperature scanning electron microscopy (LTSEM). This technique increases the resolution and ease with which samples of snow and ice can be observed, studied and photographed. Samples are easily collected in the field and have been shipped to the electron microscopy laboratory by common air carrier from distances as far away as 5,000 miles. Delicate specimens of snow crystals and ice grains survive the shipment procedures and have been stored for as long as 3 years without undergoing any structural changes. The samples are not subjected to the melting or sublimation artifacts. LTSEM allows individual crystals to be observed for several hours with no detectable changes. Furthermore, the instrument permits recording of photographs containing the parallax information necessary for three-dimensional imaging of the true shapes of snowflakes, snow crystals, snow clusters, ice grains and interspersed air spaces. This study presents the detailed descriptions of the procedures that have been used successfully in the field and the laboratory to collect, ship, store and image snow crystals and ice grains.

Last Modified: 10/24/2014
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