| Data Tables, Images, and Other Entities: |
| Data Table: | Units_and_Column_Descriptions
View Table Metadata
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Short Name: | glstkloc |
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| Download File: |
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| Data Set Owner(s): |
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Individual: | Andrew Fountain |
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Address: |
| Department of Geology, |
| 17 Cramer Hall, |
| 1721 SW Broadway, |
| Portland State University, |
| Portland, OR 97207-0751 USA |
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| Metadata Provider(s): |
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Organization: | McMurdo Dry Valleys LTER |
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Address: |
| Byrd Polar Research Center, |
| 108 Scott Hall, |
| 1090 Carmack Rd, |
| Columbus, OH 43210-1002 USA |
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| Associated Party: |
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Individual: | Hassan Basagic |
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Address: |
| Department of Geology, |
| Portland State University, |
| Portland, OR 97207-0751 USA |
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Email Address:
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| Abstract: |
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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 data set contains global positioning system (GPS) measurements of
stakes on glaciers. The measurements include both low-quality estimates (+/-
100m) from hand-held GPS units and high precision measurements (+/- 2 cm) using
Trimble (4000 SSE) geodetic receivers. The purpose of these measurements was to
obtain rough stake locations for use in relocating stakes in the future and
precise stake locations for use in calculating stake displacement. The
measurements are made relative to the WGS84 ellipsoid.
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| Keywords: |
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- glacier
(theme)
- GPS
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- global positioning system
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- latitude
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- longitude
(theme)
- elevation
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- Antarctica
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- LTER
(theme)
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| Additional Information: |
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| Note |
Data contained in these files has been subjected to quality control
standards imposed by the investigator. The user of this data should be aware
that, while efforts have been taken to ensure that these data are of the highest
quality, there is no guarantee of perfection for the data contained herein and the
possibility of errors exists. If you encounter questionable data, please contact
the MCM LTER data manager so that the data can be corrected or qualified. Thus,
these data may be modified and future data will be appended.
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| License and Usage Rights: |
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| MCM LTER data may be used freely with the following restrictions: |
The Principal Investigator be sent a notice stating reasons for acquiring any data and a description of the publication intentions.The Principal Investigator of the data set be sent a copy of the report or manuscript prior to submission and be adequately cited in any resultant publications.A copy of any resultant publications should be sent to the McMurdo data manager and principal investigator.The end-user follow the guidelines set forth in the LTER Network Data Access Policy, Data Access Requirements, and General Data Use Agreement found at http://www.mcmlter.org/data_guidelines.htm
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| Geographic Coverage: |
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Geographic Description: | Data was collected from the Canada, Commonwealth,
Howard, Hughes, Suess and Taylor glaciers, located in the Taylor Valley, McMurdo
Dry Valleys, Antarctica. This data file specifies the latitude, longitude, and
elevation of the stakes used on those glaciers. |
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Bounding Coordinates:
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| West: | 162 degrees
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| East: | 163.6 degrees
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| North: | -77.2 degrees
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| South: | -77.8 degrees
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Mimimum Altitude: | 0 meter |
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Maximum Altitude: | 1000 meter |
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| Temporal Coverage: |
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End:
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| Maintenance: |
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Description:
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Data for the original stake locations 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 ascii
text files and can be found in the McMurdo LTER data manager's home directory on INSTAAR's Unix system.
Once submitted to INSTAAR, the data manager used Microsoft Excel and Access software to produce files
that were in more of a relational mode. The resulting files are represented in the "glstkloc.dat" file (ascii text,
comma delimited format), and "glstkloc.txt" file (MS-DOS text format).
Initially, there was no date associated with each record in the data file. However, due to constant movement
of ice on glaciers, the stake locations required subsequent measurements during the 1996-97 field season.
When this occurred, a field for date was added to this file. Dates from the initial GPS measurements were
acquired from the raw data files submitted by Andrew Fountain. If uncertain about what date to use, confirmation
was made with Karen Lewis.
Upon verifying altitude corrections for the gps locations with Bjorn Johns of UNAVCO (in March, 1998), Karen
Lewis discovered that all of the ellipsoidal heights to sea level obtained by precise GPS measurements were
too short by 55.24 meters. Denise Steigerwald therefore adjusted the elevations for these stakes by adding 55.24 meters.
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 addition, Denise:
* Removed records associated with "B" (replacement) stakes. Coordinates for these stakes match those provided
for the original stakes. Data sets containing replacement stake records had their stake values divided into 'stake'
and 'stk replcmnt' fields, thus allowing the 'stake' fields to be linked between the locations file and the data files.
* Converted all latitudes and longitudes from degrees-minutes-seconds to degrees in decimal format. This would
allow them to be stored in numeric format rather than as text.
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Frequency:
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| Contact: |
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Organization: | McMurdo Dry Valleys LTER |
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Position: | Data Manager |
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Address: |
| Byrd Polar Research Center, |
| 108 Scott Hall, |
| 1090 Carmack Rd, |
| Columbus, OH 43210-1002 USA |
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| Publisher: |
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Organization: | McMurdo Dry Valleys LTER |
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Address: |
| Byrd Polar Research Center, |
| 108 Scott Hall, |
| 1090 Carmack Rd, |
| Columbus, OH 43210-1002 USA |
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| Methods Info: |
| Step 1: |
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Description:
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| Handheld measurements were acquired using either a NAVPRO
5000 or GARMIN 45 GPS unit. Latitude and longitude accuracy are about +/- 100m.
The handheld units did not provide adequately accurate elevations, so elevation
was acquired from the 1971 map of the valley. There was no special procedure in
acquiring the data or exact location relative to the stake.
The precise GPS measurements were acquired with help of
UNAVCO. (See photos and further
descriptions below). Measurements were made using a Trimble 4000 SSE
receiver. A base station was set up prior to measurements in the field. The
baseline between the measurements and basestation did not exceed 15 km. The
measurements were collected as rapid static surveys.
For the precise measurements, the GPS antenna was mounted on top of a 2 meter
tall rangepole. The rangepole was placed next to the each ablation stake on the
down-glacier side of the stake, and the tip of the rangepole was placed on the
board used for mass balance measurements at that stake to insure that the
measured elevation was relative to the same surface used in the mass balance
measurements. This system resulted in the rangepole sitting 2-3 cm away from the
down-glacier side of the ablation stake. Repeatibility of placement was
ascertained to be about +/- 2 cm based on repeat measurements. The rangepole was
always vertical, as indicated by a level-bubble.
At each stake, data were collected for 10 - 20 minutes, sufficient to keep
the horizontal precision of the GPS results within 2 cm. Accuracy of the
resulting measurements are estimated to be 5 cm in the horizontal and vertical,
after accounting for set-up error.
During the 1995/96 season, the position of all the ablation stakes on four
different glaciers were measured using rapid-static GPS. A re-measurement
in the 1996/97 season provided displacements and velocities. |
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