Antarctic Geodesy in Support of the U.S. Antarctic Program

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Antarctic Geodesy in Support of the U.S.
Antarctic Program

• Larry Hothem, Project Manager
• U.S. Geological Survey
• Reston, VA

20 November 2002
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Geodesy Program Activities

• Geodetic Reference System for the Antarctic
  continent
• International Terrestrial Reference Frame
• Support GIANT (Geodetic Infrastructure of
  ANTarctica)
• Geodetic Support to USGS and USAP Research
• Projects
• GPS Continuous Operation Reference Stations
  (CORS)
• Antarctic Remote GNSS Observatories (ARGO)
• TransAntarctic Mountains DEFormation Monitoring
  Network (TAMDEF)
• Cooperative project with Ohio State University,
  Byrd Polar Research Center
• Tide gauge measurements and calibration
• Cooperative project with Land Information New
  Zealand
• Absolute Gravity Observations

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ANTARCTIC GEODESY TECHNIQUES

• Intercontinental Baseline accuracies
• Astronomical fixes /- 400 meters
• PAGEOS (1969) /- 10 meters
• Doppler satellite (1972) /- 5 meters
• Early GPS (1985-90) /- 5-20 centimeters
• GPS today /- 3-10 millimeters

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GIANT

• Initially conceived 1992 as application of new
  space Geodesy to Antarctic mapping problems
• Space technological developments enabled
  monitoring of surface geodynamics

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GEODETIC INFRASTRUCTURE OF ANTARCTICA (GIANT)

• Objectives
• Geodetic framework for science
• basis for homogeneous spatial data
• linking isolated geodetic datums
• co-location of geodetic techniques

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Station CAMP AREA
STATION CAMP AREA Original datum point for
McMurdo and region for all mapping. Now
maintained as historical site and protected with
a berm established in December 1999.
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GEODETIC FRAMEWORK

• Permanent GPS Base Stations
• Epoch GPS Campaigns
• VLBI (Very Long Baseline Interferometry)
• DORIS (Orbit Determination and Integrated Radio
  positioning by Satellite)
• Tide Gauges
• Absolute Gravity

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International Terrestrial Reference Frames (ITRF)

• International Earth Rotation Service (IERS) -
  established since 1988 jointly by International
  Astronomical Union (IAU) and International Union
  of Geodesy and Geophysics (IUGG).
• IERS mission - provide to the worldwide
  scientific and technical community reference
  values for Earth orientation parameters and
  reference realizations of internationally
  accepted celestial and terrestrial reference
  systems.
• In the geodetic terminology, a reference frame is
  a set of points with their coordinates (in the
  broad sense) which realize an ideal reference
  system.
• The frames produced by the IERS as realizations
  of the International Terrestrial Reference System
  (ITRS) are named International Terrestrial
  Reference Frames (ITRF).
• Such frames are all of the global tracking
  stations and the related monuments which
  constitute the IERS Network, together with
  coordinates and their time variations.
• SCAR adopted in 1998 the ITRF as the fundamental
  geodetic reference system for Antarctica.

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GIANT Program Components

• Permanent geodetic observatories
• Crustal deformation network
• Physical geodesy
• Geodetic control database

• Tide gauge data
• Atmospheric impact on GPS observations in
  Antarctica
• Remote geodetic observatories
• New geodetic satellite missions

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Antarctic permanent GPS base stations

• Data from Red dots available through IGS
  (International GPS Service)
• Data from blue dots available on request from
  individual researchers

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GPS CORS - PALM

• Palmer Station
• Established in April 1997
• Ashtech Z12
• Observations at 1 Hz
• Archived at 15-sec sampling rate
• RINEX format
• Real-time broadcast
• carrier phase and
• range corrections

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GPS CORS - AMUN

• Amundson-Scott Station, South Pole
• Established in December 1991
• Ashtech Z12 (primary and backup)
• 1997 - Dorne Margolin choke ring antenna
  installed
• 1999 - Installed SCIGN radome
• Antenna operating in temperatures as low as -105F
  (-76C)
• 1999 - Began using Rubidium for EXT FREQ Standard

AMUN
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USGS performs annual survey to establish
location for Geographic South Pole
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IGS Station - MCM4

• McMurdo Station
• Established by JPL/NASA/USGS
• Allan Osborne Rogue model 8000
• Operational since January 1994

MCM4
ARR0
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MCM4
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GLONASS Observations

• International GLONASS Service - Pilot Project of
  the International Association of Geodesy
• Station CRAR - McMurdo Base, Antarctica
• Observations
• Dec 1998 - Feb 1999
• Jan 2000 to present
• Receiver JPS Legacy
• One of three stations operating in Antarctica

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Station CRAR McMurdo, Antarctica JPS Legacy
L1/L2 combined GPS and GLONASS receiver
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Stations of the Transantarctic Mountains
Deformation (TAMDEF) Monitoring Network Joint
project of the Ohio State University, Byrd Polar
Research Center, and the USGS Project start
date for TAMDEF-I November 1996 ARGO
Stations Cape Roberts (ROB1), FLM2 and FTP1
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Antarctica Remote GPS Observatories (ARGO)

• A science strategy for Antarctic neotectonic
  research
• Supported by Scientific Committee on Antarctic
  Research (SCAR) Group of Specialists on Antarctic
  Neotectonics (ANTEC)
• Dr. Terry Wilson, BPRC/OSU, Convenor, ANTEC Group
• Funded by Office of Polar Programs, National
  Science Foundation

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Permanent GPS Observatory Sites
A project of the SCAR Geodetic Infrastructure
for Antarctica (GIANT) Program
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Station COAT (Located at Mt. Coates)Established
by Dr. Carol Raymond, JPL/NASA, January 1997
Station MTCX established in December 1997.
Operations at both sites terminated in December
2000.
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Marie Byrd Land Remote GPS Stations
Project Leader Dr. Andrea Donnellan, PI,
JPL/NASA Three stations established in January
1999. Operations terminated in December 2001.
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Antarctica Remote GPS Observatories (ARGO)

• Factors considered in planning for ARGO
  deployments
• Keep it simple, if possible - e.g. no mechanical
  devices.
• avoid using wind powered generators.
• Replace mechanical hard disk data storage devices
  with PC Compact Flash Cards or similar storage
  media.
• Consider supporting high sample rate data
  requirements in special studies or
  investigations.
• Co-locate with high quality and accurate
  meteorological sensor instrumentation.
• Employ satellite data modem communications link,
  such as possible use of the Iridium communication
  satellites.

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Initial Experiences - 2000-2001

• During 2000-2001 austral summer, installed a
  GPS/GLONASS reference station system at Cape
  Roberts.
• Station is TAMDEF project benchmark ROB1.
• Initial System Design objectives
• Demonstrate and evaluate latest in technology for
  high quality low-power instrumentation
  GPS/GLONASS receiver and storage media
• System deployed Legacy-E GPS/GLONASS receiver,
  3.5 watts
• Demonstrate and evaluate feasibility for
  continuous operation without requiring wind
  generating power system.
• Demonstrate future power management and
  upgradability for remote GPS observatories.

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2000-2001 Science Objectives

• Station site selected would meet science
  objectives for
• Monitoring relationship of Cape Roberts site over
  McMurdo Sound and southern end of the Terror
  Rift, relative to IGS station MCM4 on Ross
  Island.
• Research investigations to evaluate atmospheric
  refraction effects on GPS signals.
• The SCAR GIANT and ANTEC program for optimally
  spaced GPS stations around Antarctica.
• Co-location of various geodetic and geophysical
  measurement technologies (e.g. tide gauge,
  seismic, and absolute gravity stations)

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ROB1
FLM2
MCM4
FTP1
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Cape Roberts TAMDEF Station ROB1 (1)

• In December 2000, installed GPS/GLONASS dual
  frequency observatory, Legacy-E receiver with
  solar-battery power system and hard disk data
  storage media.
• Battery supply 500 amp-hours
• Solar panels 4ea 40 watt panels
• Power required up to 6.5 watts
• Hard disk storage 3 watts
• GPS receiver 3.5 watts
• Data sampling rate 15 sec.
• Mask angle 5 degrees

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Installation at Cape Roberts (ROB1) December 2000
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Chronology of events Cape Roberts TAMDEF Station
ROB1

• 18 Dec. 2000 to 4 May 2001 - logged data
• 5 May 2001 - system shutdown because battery
  voltage dropped below 10.5 vDC
• 29 Sept. 2001 - battery voltage level restored to
  12 vDC
• 30 Sept. 2001 to 9 Dec. 2001 - system operation
  resumed automatically with normal logging of data
• 205 days of possible 356 observing days!
• 15 sec sampling rate
• Up to 14 satellites in each measurement epoch
• 9 Dec. 2001 System shutdown in order to replace
  with lower power system.

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Preliminary Analysis (1) Station ROB1, Cape
Roberts, Antarctica Processed with PAGES-V
(NGS/NOAA software)
Years
Meters
Gradient -12.6 mm/yr
North component
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Preliminary Analysis (2) Station ROB1, Cape
Roberts, Antarctica Processed with PAGES-V
(NGS/NOAA software)
Years
Meters
Gradient 13.4 mm/yr
East component
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Preliminary Analysis (3) Station ROB1, Cape
Roberts, Antarctica Processed with PAGES-V
(NGS/NOAA software)
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Remote GPS observatory goals for 2001-2 field
season

• Reduce power of Cape Robert GPS tracking system
  by at least 50 or to less than 3 watts total.
• Expand battery capacity from 500 amp-hours to
  1000 amp-hours.
• Use SanDisk 512 Mb compact flash (CF) memory
  cards for storing data.
• Install Dorne-Margolin choke ring model antennas
  with SCIGN radome cover.
• Add two new low power GPS systems at remote sites
  of the TAMDEF network.

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Installation at Mount Fleming (FLM2) in

• Site selected in order to provide
• A strong reference point upon the stable East
  Antarctic craton from which measurements of
  movement over the Transantarctic Mountains Front
  Zone and the Terror Rift can be calculated.
• A site from which tropospheric effects on GPS
  measurements in this part of Antarctica can be
  evaluated. The elevation of site is 1800 m.

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Station FLM2
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Station FLM2
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Installation at Fish Tail Point (FTP1)

• Site selected to
• Measure motion from the southernmost extent of
  the TAMDEF network.
• Provide a reference point for southward
  continuation of TAMDEF network.

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Station FTP1
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To Antenna, Second Battery Bank and Solar Panels
Solar charge controller (Sun Selector)
Low Voltage Disconnect (Sun Selector)
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Antarctica Remote GPS Observatories

• Presently feature
• Maximum power consumption of less than 2.2 Watts.
• Battery bank with storage capacity of more than
  1000 Amp-hrs.
• High-capacity hard storage media (512 Mb compact
  flash cards).
• Dorne-Margolin choke ring type antennae with
  SCIGN Radomes.
• Future Plans for ARGO stations
• Upgrade hard storage media to 1024 Mb compact
  flash cards.
• Install IRIDIUM satellite transceivers for two
  way communication and daily upload/download
  capability from each site.
• Install meteorological sensors.
• Depending on success with current installations,
  plan to expand network of ARGO sites during the
  2003-4 field season in the South Victoria Land
  region of the Transantarctic Mountains.

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Data collected at ARGO sites will be used to

• Calculate continuous baselines over McMurdo
  Sound, the southern part of the Terror Rift, and
  the Discovery Accommodation Zone.
• Evaluate the stability and quality of data from
  the IGS station MCM4 located on the volcanic Ross
  Island.
• Support the goals of SCAR GIANT program for
  optimally spaced GPS stations around Antarctica.
• Demonstrate the use of high quality low power GPS
  instruments to operate for as much of the year as
  possible.
• Support other special science objectives in South
  Victoria Land, Antarctica.

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Summary Status for ARGO Stations
LOW POWER CONTINUOUS OPERATING REMOTE GPS
OBSERVATORIESINSOUTHERN VICTORIA LANDFLM2 -
Mount FlemingInstalled Jan. 2002FTP1 - Fish
Tail PointInstalled Dec. 2001ROB1 - Cape
RobertsInstalled Dec. 2000
December 2002 field season work plan includes
visits to each of the three sites to retrieve
data (hopefully), and perform maintenance and
upgrades to firmware.
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TransAntarctic Mountains DEFormation Monitoring
Network (TAMDEF)
South Victoria Land
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Transantarctic Mountains Deformation Monitoring
Project (TAMDEF-I)South Victoria Land (1996-2001)

• 4 major GPS observing campaigns
• 12 dual frequency GPS receivers
• Dorne Margolin choke ring antennas
• Multiple day 24-hour data sets
• Repeat long baseline measurements

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Arrival Heights (ARR)
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ARR0
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Antarctic VLBI sites
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Cape Roberts Tide Gauge Station, Antarctica, Estab
lished 1991 TAMDEF Station ROB0 Established Novem
ber 1996 Remote GNSS Station ROB1 Established Dec
ember 2000
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Cape Roberts Tide Gage Station
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Calibration of Tide Gage
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Absolute Gravity Measurements

• Independent Measurements supports TAMDEF project
  objective to detect vertical motion
• 1995
• McMurdo - 2 independent measurements
• Terra Nova Bay - repeat measurement
• 1997
• Repeat measurements at McMurdo and Terra Nova Bay
• New stations Cape Roberts and Mt. Coates
• Future 2003-2004 (?)
• Repeat measurements and network of points
  extended by use of new portable Micro-g model A10
  meter
• Micro-g FG5 meter used to occupy stations at
  McMurdo, Terra Nova Bay, and possibly Cape Roberts

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FG5 Absolute Gravimeter
Cape Roberts station occupied in December 1997
Absolute Gravity Stations
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Absolute Gravity Instruments
Portable A10 Meter
FG5 Meter
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Old Gravity Base Station SATGRAV
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New Gravity Base Station THIEL
SATGRAV

THIEL
THIEL
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THIEL Gravity Base Station
McMurdo
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Thank you