Snow Survey Procedure
This article should be re-edited
WERC performs snow surveys once per year at perhaps 100 or so sites on the North Slope, aiming to capture the end-of-winter snowpack and snow-water equivalent (SWE). Some of these sites are then surveyed daily until the snow is gone.
A WERC snow survey consists of 50 depth measurements and 5 core samples. The samples are usually bagged and weighed back at camp at the end of the day.
1. Given the site coordinates, navigate to the site using GPS (set to the WGS84 datum).
2. Randomly select a starting point and direction for the depth measurements. Using a graduated probe (or MagnaProbe), take 25 measurements at (approximately) 1 meter intervals, then turn 90 degrees and take the remaining 25 measurements. The intention is to sample the snowpack without bias by avoiding or selecting drifts or bare patches.
Identifying the actual base of the snow pack is not simple or trivial, especially on tussock tundra, common at many sites.
3. Snow samples are taken using the Adirondak (TM) sampler. On suitable ground, the WERC technique is to drive the core tube into the tundra, then withdraw it with a "plug" of tundra so that the entire snow pack is sampled. On hard ground or ice it may be necessary to carefully expose the base of the core tube and take care to capture the sample using a flat shovel blade. Bag the sample in a labelled zip-lock bag. Note the bag identifier label and sample depth (of the snow, not including the tundra plug) in the field book.
4. Note other information in the field book:
- party members
- time & date
- site coordinates as read on the GPS
- brief site description
- brief note on weather conditions
5. Back at camp, gather snow samples, field books, and a scale. Tare the scale using a representative bag. Weigh (mass) each sample, noting the results in the field book. Dump the samples, open & set the bags out to dry for reuse.
6. Calculate the density for the 5 site samples, average them, then apply to the average depth of the 50 depth measurements to derive a single SWE value for the survey.
