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The geodesy and mapping program of the United States in Antarctica

Jerry L. Mullins and Larry D. Hothem, U.S. Geological Survey, Reston, Virginia 22092

The National Science Foundation (NSF) through the U.S. Geological Survey (USGS) supports geodesy and mapping in Antarctica. During the 1995-1996 season, the USGS directed its antarctic geodesy and mapping program toward management of the global positioning system (GPS) base station at McMurdo, the establishment of GPS geodetic control, topographic and satellite image mapping, seismology, management of the Scientific Committee on Antarctic Research (SCAR) Library for Geodesy and Geographic Information, and the publication of a new antarctic gazetteer.

The USGS continued its management of the International GPS Geodynamics Service (IGS) geodetic station at McMurdo station. The station, named MCM4, is located at the Radarsat facility. A Turbo Rogue 8000 receiver capable of obtaining centimeter-level positional accuracy is operated at the station. The data support activities such as improving and extending the International Earth Rotation Service Terrestrial Reference Frame, monitoring deformation of the solid Earth, variations in sea level, ice sheets, and monitoring the ionosphere.

The USGS participated in the SCAR Epoch 96 continentwide GPS campaign conducted between 20 January and 10 February 1996. The campaign connected antarctic GPS geodetic stations to stations on other continents as part of a geodetic network for geodynamics investigations. Also, the campaign connected rock-based stations to the global International Terrestrial Reference Frame. During the campaign, the USGS operated GPS stations at McMurdo Station and Amundsen-Scott South Pole Station. These geodetic data will be used to study geodynamics affecting the Antarctic and adjoining tectonic plates.

The USGS's geodetic field crew established geodetic control in the Shackleton Glacier area. The geodetic control will be used to support large-scale mapping of Vinson Massif and Bennett Platform. Also, USGS conducted geodetic surveys on Ross Island, White Island, Cape Roberts, and Marble Point and to the tide gauge at Cape Roberts. This geodetic network will assist in defining a sea-level tide datum for the McMurdo Sound area.

In January 1995, USGS surveyors conducted a geodetic survey to establish the position of the true South Pole (geodetic marker) at Amundsen-Scott South Pole Station. Using this season's observations and data from previous surveys, it has been determined that the ice sheet at the South Pole moves 9.98 meters per year in a northwesterly direction. The team installed a permanent brass marker identifying the 1995-1996 austral summer position.

Cheryl Hallam managed the digital cartography and geographic information system (GIS) program at McMurdo Station during the summer season. The program provided assistance to the automatic geophysical observations project, long-duration balloon program, the ecology and physiology of sea-ice brine microalgae, South Pole inland traverse, and the long-term ecological research project. Researchers' data were incorporated into a digital database where they became available for integration using GIS analysis.

The USGS's mapping program includes 1:50,000-scale topographic maps for areas in the McMurdo Dry Valleys. The mapping is being conducted in cooperation with the Land Information New Zealand. Under this cooperative program, the USGS obtains the aerial photographs, establishes the geodetic control, and performs the aerotriangulation. New Zealand performs the stereocompilation, collects digital cartographic data, prepares the shaded relief data, and provides color separates. The USGS will print the maps. The maps cover the Taylor and Wright Valleys, the Convoy Range, and Royal Society Range in the McMurdo Dry Valleys area. These 1:50,000-scale, 15-minute topographic maps have 50-meter contour intervals and 25-meter supplemental contours. The maps will include existing and new place names approved by the U.S. Board on Geographic Names (BGN). Five maps covering part of the Royal Society Range were published in August 1993 and seven additional maps will be published in 1997.

The USGS published the second version of the advanced very-high-resolution radiometer digital image map of Antarctica at 1:5,000,000 scale. This version contains contour data, permanent station locations, and BGN place names. This map was printed in July 1996. Also, a large-scale photomap of McMurdo Station was published in November 1995.

The USGS's South Pole seismic program continued operation during the 1996 austral winter season. The seismic station serves as a key station in the Worldwide Standardized Seismograph Network. These data are used by the USGS National Earthquake Information Center to help locate earthquake epicenters and origin times for seismic wave propagation.

The USGS manages the SCAR geodesy and geographic information library for the U.S. Antarctic Program. The library is the official depository and distribution point for antarctic photographic and cartographic products produced by the United States. The library has approximately 450,000 black-and-white and color aerial photographs of the Antarctic dating from Operation Highjump (1946-1947) through the 1995 field season. The library also houses geodetic control records, satellite images, maps, charts, and publications. These maps, charts, and publications are exchanged with other nations under the provisions of the Antarctic Treaty.

A new edition of the U.S. antarctic gazetteer, Geographic Names of the Antarctic, containing approximately 13,000 official decisions of the BGN was published in November 1995. It was compiled and edited by Fred G. Alberts. The gazetteer catalogs decisions made through 1994 in the same format as the 1980 edition, including name, geographical coordinates, descriptive text, and reason for naming. As in the 1980 edition, variant (unofficial) names will appear as cross-references to the official entry. All variant names will also be listed along with the related official name.

In parallel with publication as a textual reference, the information in the new gazetteer was converted to a digital database as part of the Geographic Names Information System (GNIS) of the United States. The digital file will be released in the near future to the Internet as a digital gazetteer with software for searching and analyzing the data.

These programs were funded by National Science Foundation grant OPP 91-14787.