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Project at a Glance

Project Status: complete

Report Published July 1989:


Title: Evaluation of methods for measurement of snowfall and collection of snow for chemical analysis

Principal Investigator / Author(s): Berg, Neil

Contractor: USDA Forest Service and UC Santa Barbara

Contract Number: A6-078-32


Topic Areas: Acid Deposition


Abstract:

This study developed and assessed methods for monitoring snowfall and its chemical constituents. Specific objectives were to:

1) Compare measurements of snow (or snow and rain) volume and chemical concentration from several monitoring devices or procedures.
2) Develop and document guidelines for sampling interval, collection, storage, transport, and processing techniques, and equipment selection for point monitoring of snow (or snow and rain) volume and chemical concentration.
3) Evaluate one sampling technique, snowpack sampling, at spatially distributed sites receiving a wide range of snowfall amounts and potentially widely varying snow chemistries.

Snow water equivalent and chemical concentrations were compared between large (32-cm by 122-cm) polyvinyl chloride (PVC) tubes, Belfort precipitation gauges, snowboards, and snowpack samples at an exposed site, near Mammoth Lakes, and in a forest clearing, near Soda Springs, during two recent winters. An Aerochem Metrics collector was also included at the forest site. At the exposed site, the tubes and the Belfort gauges caught 23% less snow water equivalent than the snowboards. In the clearing, the tubes and the Belfort gauges caught 24% more than the snowboards one winter and 20% more the second winter. Except for NO3 at the forest site, H+ , NO3 and SO4 concentrations of samples from the tubes and the snowboards. differed significantly. Although laboratory tests showed no adsorption or desorption of synthetic standard solutions of major ions with the PVC tubes, the differences in concentrations in field samples between the snowboards and the PVC tubes and brittleness of the PVC tubes in cold weather prompt the recommendation that PVC tubes not be used in an operational snow monitoring program. A linear polyethylene (LPE) tube of the same dimensions collected as much snow water equivalent as did the Belfort gauges in the second year of the study. The LPE did not exhibit brittleness during operational field conditions. In areas where forest cover exists and both rain and snow occur, shielded LPE tubes should be used for weekly monitoring of water equivalent and chemistry if they do not contaminate the precipitation samples. At higher elevation sites experiencing moderate to high winds and no winter rain, sampling should be weekly by snowboard. The Aerochem Metrics sampler is not suitable for snow collection in areas of moderate to high snowfall because of undermeasurement problems, mechanical malfunctions in cold, wet environments, and small bucket capacity. A modified snowboard, with a reservoir for melt or rain water should be designed and evaluated at sites receiving rain and snow.


 

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