Barrow

A high-precision GNSS (RTK and post-process) surveying system in Barrow, Alaska provides centimeter level differential corrections to properly equipped users in the vicinity of the Barrow Environmental Observatory (BEO), allowing for stake-out surveys and real-time survey data collection. The equipment may also be used for post-processed static and kinematic surveys with post-processing software available from EarthScope. The system is not compatible with hand-held GPS navigation receivers.

GNSS base station data access (station ID: BARO)

A geodetic system consisting of a dual-frequency base station and roving receiver is available in Barrow. By collecting and post-processing data, centimeter-level accuracy can be realized over 100 kilometers away from Barrow. A second GPS base station in Barrow, the Barrow SuomiNet site SG27, provides a backup to the BASC base station for post-processing. Note that a separate base station is maintained by EarthScope in Atqasuk, AK for surveys in that area. Data from site BARO, SG27, and ATQK are available from the NSF GAGE data archive.

In addition, the base station transmits real-time kinematic (RTK) broadcasts at 418 MHz (CMR+ format at 9600 baud). This provides real-time centimeter-level capability within a ~10 km radius of the BARC building. A second portable RTK radio repeater is available to assist RTK work elsewhere in the Barrow area.

The following GPS equipment is available for use in Barrow:

• Trimble NetR8 GNSS Base Station
  Geodetic GNSS base station for data collection and RTK broadcasting. An equipment inventory is maintained on this page.

• R8 GNSS Rover Survey Systems
  Geodetic GPS receiver and ancillary field equipment that provides centimeter accuracy in real-time (RTK) or through data collection and post-processing. An equipment inventory is maintained on this page.

• Barrow SuomiNet GPS Station SG27
  A fixed geodetic GPS base station is located at the NOAA GMD Facility, and provides a post-processing backup to the GPS base station at BASC. RINEX data files (15 sec) are available. Higher-rate data are also available, but are only downloaded upon request and are not archived. Note that high-rate data is stored in a ring buffer on the receiver and will not persist indefinitely, therefore data requests should be made as soon as possible after the need is identified.
• SG27 coordinates (Survey Mark):
  • ITRF-05, June 1 2010: 71 19′ 22.4187″ N 156 36′ 37.1960″ W 9.430m HAE
  • NAD-83, June 1 2010: 71 19′ 22.4293″ N 156 36′ 37.0618″ W 8.865m HAE
  • Antenna Reference Point (bottom of antenna mount) is 0.008m above Survey Mark.

• Elevation above mean sea level (Survey Mark):
  • GEOID-99 model applied to NAD-83 coordinates, June 1 2010: 11.187m MSL

Support

Support to survey system users is provided by several organizations. EarthScope provides equipment and technical support, including training on the Barrow GNSS systems per request. UMIAQ provides oversight of the equipment, and manages equipment scheduling and check-out/check-in to users. The GPS base station equipment is hosted at BARC, and University of Alaska at Fairbanks assists with network connectivity to the base station. CH2M Hill Polar services provides logistical support.

Users who intend to use the equipment for a significant amount of field surveying are strongly encouraged to arrange for training prior to their field season. Remote (email and telephone) support is also provided, and EarthScope personnel may also be available for on-site field support for projects with a significant GPS surveying component. Upon project completion, permanent GPS data and metadata archival is available.

Documentation

Collecting and processing quality GNSS data requires a systematic approach and an understanding of the basics of GNSS surveying. The following resources are available for Barrow GNSS users.

• The Barrow Area Information Database, maintained by UTEP, provides documentation tailored to performing surveys with the Barrow system.
• System documentation is available at Barrow, including GPS software and equipment manuals.

Want to Test the System?

New users are encouraged to use the system to survey or stake out well known points as a shakedown exercise to gain familiarity with the system prior to conducting surveys for their own research. The following benchmark provides a useful test point for tutorial surveys, or as a control point during field surveys. Post-processed and RTK survey coordinates of this point will agree within 2cm horizontal and 5 cm vertical if the surveying and processing was done correctly. Use a handheld GPS to locate the benchmark if necessary.

NGS Benchmark S123, NAD-83 (1675 meters from BASC)

71 18′ 48.39714″ N, 156 38′ 51.88695″ W, 5.404m HAE (7.698m MSL, GEOID-99)