SnowMicroPen

The SnowMicroPen is an instrument co-developed by Martin Schneebeli of the Swiss Federal Institute for Snow and Avalanche Research (SFISAR) and Jerry Johnson of the Cold Regions Research and Engineering Laboratory.  This instrument is a constant-speed probe that is driven through the snow, providing the user with 250 hardness measurements per mm resulting in extremely detailed snow profile and snow structure information.

This instrument has evolved over the last 40 years.  The original resistograph was developed by Charles Bradley in the 1960s while he was working as a Professor in the Department of Earth Sciences at Montana State University.  In the mid-1980s, Bob Brown (Professor in Civil Engineering at MSU) and graduate student Tim Dowd enhanced the idea of Bradley's resistograph to include a probe with a load cell and a microprocessor.   The resulting "Digital Resistograph" was further enhanced in the late-1980s by Karl Birkeland while he was working on his MS research at MSU.  Cooperatively, Schneebeli and Johnson worked through many existing technical problems to come up with the current, much-improved instrument.  Given the history of this instrument, the Forest Service National Avalanche Center and Montana State University are excited to be able to test and use the new and improved "SnowMicroPen".   

In an agreement arranged by Montana State University Techlink, the Forest Service National Avalanche Center cooperated with SFISAR, CRREL, Montana State University, and CF Electronics to obtain and a SnowMicroPen during the 2000/2001 season, and has used one since that time.

The high resolution signal of the SnowMicroPen allows the identification of not only the hardness of specific layers, but also the grain types as well as calculations of some of the mechanics of the snow structure. Because many measurements can be conducted relatively rapidly, the National Avalanche Center, and SFISAR, have been using the SnowMicroPen for studies of spatial variability. A number of publications utilizing the SnowMicroPen are listed below the photographs.

 

   Close up view of one of the first SnowMicroPens, Switzerland, 2000

 

     

Demonstrating the use of the SnowMicroPen in Montana, 2001

 

Utilizing the SnowMicroPen for spatial variability research, Montana, 2002

 

Technical papers using the SnowMicroPen

Birkeland, K., K. Kronholm, and S. Logan. 2004. A comparison of the spatal structure of the penetration resistance of snow layers in two different snow climates. Proceedings of the International Symposium on Snow Monitoring and Avalanches, Manali, India, in press. [Article]

Birkeland, K., K. Kronholm, M. Schneebeli, and C. Pielemeier. 2004. Changes in the shear strength and micro-penetration hardness of a buried surface hoar layer. Annals of Glaciology 38, 223-228. [Abstract] [Article]

Johnson, J., and M. Schneebeli. 1999. Characterizing the microstructural and micromechanical properties of snow. Cold Reg. Sci. Tech. 30(1-3), 91-100.

Pielmeier, C. and M. Schneebeli. In press. Snow stratigraphy measured by snow hardness and compared to surface section images. Cold Reg. Sci. Tech.

Pielmeier, C., M. Schneebeli, and T. Stucki. 2001. Snow texture: a comparison of empirical versus simulated texture index for alpine snow. Ann. Glaciol. 32, 7-13.

Schneebeli, M., C. Pielmeier, and J. Johnson. 1999. Measuring snow microstructure and hardness using a high resolution penetrometer. Cold Reg. Sci. Tech. 30(1-3), 101-114.