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TAMDEFI Project TransAntarctic Mountains Deformation Monitoring Network

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TAMDEF-I Project (TransAntarctic Mountains Deformation Monitoring Network) ... In November 1996, the Byrd Polar Research Center/Ohio State University, jointly ... – PowerPoint PPT presentation

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Title: TAMDEFI Project TransAntarctic Mountains Deformation Monitoring Network


1
TAMDEF-I Project (TransAntarctic Mountains
Deformation Monitoring Network)
  • L. Hothem (1) and M. Willis (1,2)
  • (1) U.S. Geological Survey
  • (2) Byrd Polar Research Center, Ohio State
    University

Antarctic Geodesy Symposium, AGS01, Saint
Petersburg, Russia, 18-20 July 2001
2
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3
South Victoria Land TransAntarctic Mountains
DEFormation Monitoring (TAMDEF-I) project
4
In November 1996, the Byrd Polar Research
Center/Ohio State University, jointly with the US
Geological Survey, began work on establishing a
network of about 30 stations located at sites in
the South Victoria Land region of the
Transantarctic Mountains. The 4th and last in
series of GPS observing campaigns for this phase
of the studies was completed in the December
1999-January 2000 field season. High quality
data were obtained in each of the 4 observing
campaigns. Objective test predictions of
leading models for ice sheet change and tectonism
5
Transantarctic Mountains Deformation Monitoring
Project (TAMDEF) South Victoria Land
  • Cooperative project - Ohio State University and
    USGS
  • Three GPS observing campaigns completed
  • 1996-97, 97-98, 98-99, and 99-00 field seasons
  • Objective test predictions of leading models
    for ice sheet change and tectonism
  • Other geodetic measurements
  • International GPS Service (IGS) stations in and
    near Antarctica
  • Absolute gravity
  • Tide gages

6
Transantarctic Mountains Deformation Monitoring
Project (TAMDEF) South Victoria Land
  • TAMDEF-I -- Four GPS Observing Campaigns
  • 1-year intervals
  • Field seasons 1996-97, 97-98, 98-99, and
    99-2000
  • Measure rock motion - 3-dimensional
  • Expected signals are
  • 1. Glacial rebound
  • 2. Tectonic
  • 3. Volcanic
  • Directions and patterns of these motions mostly
    distinct
  • GPS measurements designed to discriminate among
    them
  • Test predictions of leading models for ice sheet
    change and tectonism
  • Long-term project
  • TAMDEF-II is planned

7
GPS surveys formed geometrical elements generally
at three spatial scales
  • Long baselines (100 to 400 km) that span the
    features most expected to show motion.
    Simultaneous tracking time is at least 2 days,
    often 7 days.
  • Station at Cape Roberts (ROB0) occupied
    continuously during each of the 4 observing
    campaigns.
  • Some other stations with continuous data sets
    spanning periods of up to 15 days.
  • Short baselines (10 to 25 km) crossing suspected
    fault zones. Simultaneous tracking time 2 to 24
    hours.
  • Very short baselines (0.05 to 0.20 km) at each
    site (footprint array) to test for local motion
    due to such processes as frost action.
    Simultaneous tracking time is generally 60
    minutes.

8
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9
BTL
MCM4
ERR
ARR
ROB
TAMDEF Station
Local fault surveys
Other GPS Reference Stations
Absolute Gravity Station
10
To obtain high accuracy or mm-level GPS
measurements where biases are adequately modeled
or minimized and which are free of blunders due
to human error, requires careful planning and
successful execution of the field methodologies
employed.
11
Field Procedures
(1) Special pins set in rock outcrop (2)
Established a set of reference points,
footprint array, at each site to monitor
stability of the primary monument (3) Used
specially designed fixed-height level mounts to
ensure at a high confidence level, sub-mm
repeatability for the relationship of antenna
reference point (ARP) to the monument
reference point (4) Employed late model GPS
receivers with Dorne Margolin model choke ring
antennas (5) Collected multiple-day 24-hour data
sets simultaneously at 8 to 12 stations
12
TAMDEF Monuments
Nylon cap to protect threads
Plastic marker stamped with 4-character station
name
Threaded stainless steel 20-cm rod glued into
hole drilled in bedrock
13
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14
Attaching and leveling the antenna mount
15
Special Fixed-Height Level Mount for TAMDEF
Monuments
ARP
Station ARR0 located adjacent to IGS station MCM4.
At each station of the TAMDEF network,
relationship of Antenna Reference Point (ARP) to
station mark (bottom of divot for stainless steel
pin) is repeatable for each setup at the sub-mm
level.
16
Arrival Heights (ARR) TAMDEF Network
IGS Station MCM4
TAMDEF Station ARR0
17
IGS Station - MCM4
  • McMurdo Station - Operational since January 1994

MCM4 with raydome cover
MCM4
ARR0
18
GPS Equipment
Receiver Models
Ashtech Z12 Trimble SSE and SSi
Antenna Models
Ashtech Trimble Dorne Margolin Choke Rings
19
Footprint Array for ARR
20
Cape Roberts (ROB)
21
Footprint Array for ROB
ROB0
22
Station ROB0
23
Cape Roberts Tide Station (Installed
1991) co-located with TAMDEF Station ROB0 (Establ
ished November 1996) Install permanent GPS/GLONAS
S observing station during 2000-2001 field season
24
Bettle Peak (BTL)
Footprint array
25
TAMDEF Station ERE Mount Erebus, Antarctica
26
Reliable Power Supply Essential for Continuous
Data Collection
Transport Case and Site storage for GPS receiver
and two 40 amp-hour gel-cell batteries
30-watt solar panel generating system
27
Details on Field Procedures
  • Sites selected with relatively clear horizon
  • No obstructions above 10?
  • Minimal obstructions above 5?
  • Mask angle for data collection 5?
  • Data collection sampling rate
  • Daily (24-hour) data sets 30-sec or 15-sec
  • Footprint surveys 5-sec
  • Data management
  • All raw data translated into RINEX format
  • Categorized by station location and day of
    operation
  • Compressed and stored on CD-ROMs
  • Documentation for site and each occupation
  • Description of geology at each site
  • Satellite sky view
  • Model and serial numbers of GPS equipment used
  • Duration of site occupation

28
Quality Analysis Data Processing
  • Data quality analysis
  • TEQC Toolkit by UNAVCO
  • 24-hour data sets
  • Precise point positions computed by use of
    JPL/NASAs automated GIPSY-OASIS II package
  • Differential positions computed by use of
    National Geodetic Survey/NOAAs PAGES package
  • All processed using IGS orbital coordinate data
  • Footprint array surveys
  • Software packages used include
  • GPSurvey V2.3
  • Ashtech GPPS
  • Magellan AOS

29
SUMMARY
  • Methodology employed for TAMDEF GPS observing
    campaigns was successful overall in meeting goals
    for
  • data free of errors due to blunders
  • minimizing multipath effects
  • multiple-day data sets relatively free of gaps
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