Not just frozen water:
Measuring snow’s nitrogen pulse
Sarah J. Nelson, University of MaineHannah Webber, SERC Institute
Ivan Fernandez, University of Maine
“Snow on the ground is a dynamic medium.”
- Mark Williams, UC Boulder
See: http://snobear.colorado.edu/Markw/Intro/Snow/MtnSnowpack/snowpack.html
Snowfall:
• Freshly fallen snow. • For example, 2.5 inches of snow fell
in Bangor on Feb. 27, 2010.
Snowfall: Protocol 9
Snowpack:
• Accumulated snow on the ground. • E.g., Snowpack
was 36 inches on Feb. 26, 2010.
www.arts.monash.edu.au
Snowpack: Protocol 9
Snow Water Equivalent (SWE):
• “the amount of water contained within the snowpack.
• It can be thought of as the depth of water that would theoretically result if you melted the entire snowpack instantaneously.”
www.or.nrcs.usda.gov/Snow/about/swe.html
Snow water equivalent: Protocol 10
Snow Density:
• the ratio of the volume of meltwater that can be derived from a sample of snow to the original volume of the sample.
• E.g., 1.2" water equivalent divided by 15" of snow = .08 density (= 8%).
We will measure snow melt:Surface runoff produced from melting snow
How much water?
Stream stage: Protocol 8
ga.water.usgs.gov/edu/measureflow.html
How much nitrogen through the snowmelt period?
Nitrogen in stream water: Protocol 7
Snowmelt is surface runoff, but
• By the time it’s in the stream, was are also measuring what has moved through the watershed (some soil signal, existing water in the stream)
• Other protocols deal with soils and watershed characteristics – these give students’ questions some dimension!
Acadia Learning is a joint effort of the Schoodic Education and Research Center (SERC) Institute at Acadia National Park, the University of Maine, and Maine Sea Grant.
It is supported by:
• National Science Foundation (DEB 1056692)
• Maine Department of Education
• National Oceanic and Atmospheric Administration
• Private donors
Watershed scale: snow cover
• Which places have snow, and how patchy is it?
www.nohrsc.nws.gov/interactive/html/map.html
Density & SWE math
• Snow Density = Snow Depth / SWE Density must be in decimal form. For
example: 25% = 0.25 Density is usually specified in kilogram
per cubic meter (kg/m3). • The density of water is 1000 kg/m3 and snow
density is usually measured as a ratio to this. • So snow which is 100 kg/m3 is specified as
100/1000, or 10% (of the density of water). www.avalanche-center.org/Education/glossary
What’s in that snow?
• Like rain, needs a condensation nucleus to form
• Then particles and gases can glom on as snow forms, grows, travels Snow crystal photos – check out:
http://www.its.caltech.edu/~atomic/snowcrystals/class/class.htm