Geodesy in the 21st century

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Geodesy in the 21st century

• Shimon Wdowinski
• University of Miami
• Susan Eriksson
• UNAVCO

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Geodesy - it aint what it used to be

• Geodesy and space-geodesy
• What is geodesy?
• Historical perspective
• Space-based technologies
• Applications
• Lithosphere (Solid Earth)
• Hydrosphere
• Cryosphere
• Atmosphere Ionosphere
• Geodesy and Big Ideas of geoscience

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Geodesy

• Geodesy is the science of accurately measuring
  the Earths size, shape, orientation,
  gravitational field and the variations of these
  quantities with time.

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Geodesy
Eratosthenes (276 BC - 194 BC) measured the shade
angle between Alexandria and Syene (Egypt) and
distance. Earths circumference 252,000 strades
(roughly 46,000 km, only 15 higher than the
current estimate).
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Geodesy in the 21st century

• Space geodesy has application in areas of great
  societal impact such as climate change, water
  resources, and natural hazards and disasters.

New Orleans subsidence
Sea level change
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Space Geodesy

• Space or satellite geodesy completely
  revolutionized the field of geodesy in both
  accuracy and availability of measurements.
• This era began in the 1970s with the
  utilization of exciting radio-telescope
  technologies (Very Long Baseline Interferometry
  VLBI).
• Initial accuracies 5-10 cm.
• Current accuracies sub-cm.

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Tectonic plate motion
Revel-1 (Sella et al., 2004)
Observations VLBI, SLR, DORIS, GPS
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Space geodetic technologies

• Positioning techniques
• Global Navigation Satellite Systems (GNSS)
• Altimetry
• Interferometric Synthetic Aperture Radar (InSAR)
• Gravity missions

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Positioning techniques

• Very Long Baseline Interferometry (VLBI)
• Satellite Laser Ranging
• Lunar Laser Ranging
• Doppler Orbit determination and Radiopositioning
  Integrated on Satellite (DORIS)

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Global Navigation Satellite Systems (GNSS)

• Global Positioning System (GPS)

• GLObal NAvigatsionnaya Sputnikovaya Sistema
  (GLONASS)
• Galileo (European, 1st launched 2005)
• Beidou-1(China, test launch 2000)
• IRNSS (India, in planning)

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Altimetry

• SeaSAT
• GeoSAT
• TOPEX/Posiedon
• Jason-1
• ERS-2
• ENVISAT
• ICESAT
• CryoSAT

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Interferometric Synthetic Aperture Radar (InSAR)

• SeaSAT
• ERS-1/2
• JERS-1
• RADARSAT-1
• ENVISAT
• ALOS
• RADARSAT-2
• TerraSAR-X
• COSMO-SkyMed

Repeat path data acquisition
Calculating phase changes
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Gravity missions
LAGEOS-1

• LAGEOS-1/2
• Ajisai
• CHAMP
• GRACE
• GOCE

GRACE
Measurements of small changes in the Earths
gravitational field
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Applications
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Earthquake deformation cycle
Elastic rebound theory
GPS time series
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Earthquake induced deformation
M6.6 B, 2003 Bam earthquake (Iran)
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Magmatic induced deformation
GPS, InSAR
Magmatic inflation prior to eruptions
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Volcano Monitoring
Studies of hazardous volcanoes in México, Central
America and the Caribbean Monitor eruption
pre-cursors
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Slow slip events
Seismicity and hazard at subduction zones
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Urban and infrastructure subsidence
New Orleans subsidence (2002-2004) prior to
Hurricane Katrina
Dixon et al. (2006)
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Geoid determination
Long term geoid shape reflecting mass
distribution within the Earth
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Global and regional water budget
Short-term changes of the geoid reflect mainly
water and ice mass redistribution
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Wetland water level changes
InSAR monitoring of water resources (Everglades,
south Florida)
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Soil moisture
Soil moisture is critical for vegetation growth
and survival. It can be monitored by InSAR and
GPS.
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River and lakes water levels
Remote monitoring of water resources
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Glacier Flow
InSAR measurement
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Landslides
Ground movements in Berkley Hill, near San
Francisco (InSAR monitoring)
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Subsidence aquifer system deformation
Las Vegas - Subsidence due to water extraction
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Hydrocarbon production
Surface subsidence due to oil extraction
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Measuring the Atmosphere and Ionosphere
Perceptible water
Total Electron Content
GPS measurements are sensitive to changes in the
atmosphere and ionosphere.
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Conclusions

• Small changes of the Earths solid and aquatic
  surfaces with cm- and sub-cm level accuracy
• A variety of application include
• Lithosphere (earthquakes, volcanoes, subsidence)
• Hydrosphere (oceans, rivers, lakes, wetlands)
• Cryosphere (icecap, glaciers)
• Atmosphere Ionosphere (Perceptible water, TEC)
• Anthroposphere (urban subsidence, oil fields)
• Societal important issue
• global climate change,
• sea level rise and
• natural hazard mitigation

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Related but..

• Big Idea 2 Earth is 4.6 billion years old. 2.7
  Over Earths vast history, both slowly acting and
  catastrophic processes have produced enormous
  changes. Supercontinents formed and broke apart,
  the compositions of the atmosphere and oceans
  changed, sea level rose and fell, living species
  evolved and went extinct, ice sheets advanced and
  melted away, meteorites slammed into the Earth,
  and mountains formed and eroded away.
• Big Idea 4 Earth is a continuously changing
  planet.
• 4.1 Earth? geosphere changes through geological,
  physical, chemical, hydrological, and biological
  processes that operate according to universal
  laws.
• 4.7 Landscapes result from the dynamic interplay
  between processes that form and uplift new crust
  and processes that depress and break it down.

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How do we do science?

• 3.4 Earth systems interact over a wide range of
  scales of space and time.
• These scales range from microscopic to global in
  size and operate over fractions of a second to
  billions of years.

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21st century Geodesy

• Big Idea 5 Earth is the water planet.
• The availability and distribution of clean,
  accessible water affects the security and quality
  of human life. Once contaminated, water quality
  is difficult to restore. In many places, both
  surface water and groundwater are withdrawn
  faster than they are replenished.

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• Upcoming resources for broader education related
  to modern geodesy
• Upcoming EOS article
• Websiteunavco.org/geodesy21stcentury
• Poster series published in 2009
• Community working on curricular materials
  appropriate for different college classes.