snow

Glacier Snow Densities

Abstract: 

As part of the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, a systematic sampling program has been undertaken to monitor mass balance and meltwater flow from the Taylor Valley glaciers. This dataset contains snow density measurements determined at each stake with snow present on the glaciers of Taylor Valley. Included here for each stake are the snow thickness and density for each layer and the average density for each pit.

Additional Project roles: 

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Purpose: 

The goal of each summer season is to take measurements in early spring (Oct/Nov) and late summer (late January). This provides a measure of seasonal winter/summer changes of glacier mass.

Data sources: 

COM_SNWDNS
HOW_SNWDNS
CAN_SNWDNS
TAY_SNWDNS

Methods: 

The average snowpack density is determined by digging a snowpit near each of the stakes that has any amount of snow present on the surface. The snowpit is dug to the surface of the ice for stakes in the ablation zone and to depth of the previous year's snow surface in the accumulation zone. The different layers in the snowpit are identified in the field. The thickness of each layer is measured and a sample is collected using a 100cm3 metal sampler. Excess snow is removed by a brush and the contents are placed in a pre-weighed bag. The weight is measured using a spring scale. Note about measurement timing: The goal of each summer season is to take measurements in early spring (Oct/Nov) and late summer (late January). This provides a measure of seasonal winter/summer changes of glacier mass. In some circumstances we have the opportunity or need to measure the glaciers in mid-season (Dec). View the dates the measurements were made at the following URL: http://www.mcmlter.org/data/glaciers/timing/snowdates.pdf A Note about Stake names: A stake with an H or V indicates a stake along the ice cliff that forms the boundary of the glacier terminus. An H is a horizontal stake placed into the vertical wall of the glacier terminus, and V is a stake placed into the ice apron at the base of the ice cliff. The vertical stakes were installed to support the horizontal stakes and provide a nearby measure of ablation for a surface with a much different slope.

Maintenance: 

Data for the glacier snow densities was submitted by Andrew G. Fountain to the data manager in  August, 1997. The column showing "file name" identifies the original file containing that record. 
                        
These are provenance ascii text files and can be found by the McMurdo LTER data manager's office. 
 
Once submitted, the data manager used Microsoft Excel, Access or/and Toad for Oracle software to produce files that were in more of a relational mode.
                        
  In March, 2000, Thomas Nylen submitted data from the 1997-98, 1998-99 and 1999-2000 seasons. Instead of lumping all of the snow density values for each glacier under one file, they were 
  separated into files for each glacier. Metadata fields were also completed at this time.
                        
 In April, 2000, Denise Steigerwald added fields for dataset code and glstkid. Dataset code would allow  the data to be linked to the metadata in a relational database. Glstkid is a code that ties stake records to points on a GIS base map being developed by Michael Prentice at the University of New Hampshire.  
                  
In 2006, Chris Gardner and Inigo San Gil standardized the metadata using the EML format. In addition, metadata was distributed at the LTER Metadata catalogs and Federal metadata clearinghouses.
 
In 2014, metadata was revamped by Inigo San Gil, using the Drupal Ecological Information Management System (DEIMS)
 
Metadata completed in 2016

Additional information: 

In some circumstances we have the opportunity or need to measure the glaciers in mid-season (Dec). 
                
View the dates the measurements were made at the following URL: http://mcmlter.org/sites/default/files/snowdates.pdf
 
            

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