Data Description

Data Description

The Intensive Snow Measurements data portal includes over 25 different physical and chemical snowpack property measurements that were measured daily or near-daily over the course of four New Hampshire winters (2013-2016). The detailed information collected from New Hampshire’s snowpack allows for complex analysis of the role of snowpack in the ecosystem.

Data Collection Procedures

Data collection procedures for this project included the following:

1. Initial Snow Albedo measurements were taken:

  • Snow Albedo: Snow albedo is the reflectivity of the snow at individual wavelengths (350nm-1750nm) in 1nm resolution. Average spectral albedo (averaged over 5 readings) are included for each day when measurements were made.

2. A snowpit was dug and these measurements were taken:

  • Snow Optical Grain Size: Snow optical grain size data was collected at discrete depths throughout the snowpack. The optical grain size changed as the snow metamorphosed throughout the winter season, changing from fresh precipitation particles to old rounded grains. 
  • Snow Depth: The technician dug a snowpit and measured the total depth of the snowpack perpendicular to the soil surface with a ruler.
    • Layer ID (YYMMDD): Metric taken beginning in Winter 3, this is a time code used to represent the approximate day the snow layer(s) within the sample(s) were deposited.
  • Temperature: The temperature was taken at the approximate location where each sample was excavated.
  • Grain Size and Type: Grain size and type were determined with the aid of a magnifying glass.

3. Snow samples were then extracted from the snowpack for measurement:

  • Orientation: If the technician held the density cutter vertical for a long stratigraphic sample (greater than 3 cm in most of Winter 2 and all of Winter 3 and 4), orientation was marked with a 6. If the technician held the density cutter horizontal for a short stratigraphic sample (0-3 cm), a 3 was marked.
  • Sample Depth: The depth of each sample was recorded during excavation in order to calculate the total volume for density and snow-water equivalence.
  • Snow Density: The individual tared bottle weight was subtracted from the filled bottle weight and a total snow mass was calculated. Total snow mass was divided by the total volume of the snow sample (calculated from the total volume of the cutter multiplied by the number of scoops) in order to calculate sample density.
  • Snow Water Equivalence (SWE): Sample density was multiplied by the vertical sample height in order to calculate a mass of water per area unit. Individual sample SWE were then added to other individual sample SWE for the day to obtain a total snowpack (integrated) SWE for any given day.

4. After physical properties were measured, the chemistry of each sample was measured:

  • Black Carbon: Prior to analysis, a snow sample was melted, sonicated for at least 15 min, and an aliquot was transferred to a clean 30 mL analysis bottle. Just before entering the SP2, the liquid snow sample was drawn into a nebulizer via a peristaltic pump. The nebulized sample was then quickly heated and cooled and finally analyzed for BC mass (ng/m^3) on the SP2. 
  • Major Ions: (see Metadata Snapshot) After analysis on the SP2, melted snow samples were queued for analysis via ion chromatography where a measurement of specific ion concentrations was made in nmol/L. Quality control followed analysis, with determinations of quality based on concentrations of specific ions in the sample as well as the samples location within the snowpack.