not just frozen water: measuring snow’s nitrogen pulse

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