2D1 Parallelsessies Week Digitaal Erfgoed: Patricia Alkhoven / Meertens Instituut
EarthScope GPS Tutorial PBO Geodetic Instrumentation – GPS Principles, Data Access and...
-
Upload
maximilian-white -
Category
Documents
-
view
214 -
download
0
Transcript of EarthScope GPS Tutorial PBO Geodetic Instrumentation – GPS Principles, Data Access and...
EarthScope GPS Tutorial
PBO Geodetic Instrumentation – GPS Principles, Data Access and
Applications
Chuck Meertens, David Phillips, Freddy Blume,
Mike Jackson, and Greg Anderson
UNAVCO, Boulder, CO
EarthScope in the Northern Rockies Workshop
Bozeman, Mt
17 September 2005
Outline
Science Introduction
GPS – Briefly how it works
Achieving High precision GPS results
GPS Science Examples
PBO Instrumentation
and Data
GEO-EarthScope
UNAVCO Facility-supported PI science includes plate tectonics, boundary zones, earthquakes and tectonics, volcanoes and active magmatic systems, glacial movements and isostatic adjustment, delta subsidence and precision mapping.
GPS Science: Global PI Research Projects
GPS – the global perspective
GSRM Model of Kreemer and Holt
Observed GPSVelocities
Plate TectonicModel with DeformableBoundaries Model Velocities and Plate
Boundary Strain
Global Plate Motions and Boundary Zones
5170 geodetic velocities from 86 different studies
• 24+ satellites• 6 orbital planes• 55 degrees inclination• 20,200 km altitude• 4 satellites in each
plane• 12 hour orbital period• 4 satellites visible
GPS: The System and How it works
Space Segment
Satellite Signal Structure
Carrier phase L1 L2
Frequency 1575.42 MHz 1227.60 MHz
Wavelength 19cm 24cm
Code Modulation C/A-code L2C-Coming…
P(Y)-code P(Y)-code
NAVDATA NAVDATA
Carrier
C/A-code
P-code
NAVDATA
ReceivedSignal
What your Geodetic GPS receiver measures…
Code Range Results
Autonomous Position+/- 10 m (30 ft) error (horizontal)+/- 15 m (45 ft) error (vertical)
Your location is:45o 30.323’ N
111o 45.162’ W
Carrier Phase Solutions
= First Partial Wavelength
N
N = Integer Ambiguity
D
Distance D = N +
For highest precision (mm-level) coordinates use:-Carrier phase to determine ranges-Dual-frequency receivers-Good monuments-Multiple stations-Sophisticated processing software-Collect lots of data
PBO Precision ~1 mm horizontal ~ 3-4 mm verticalFrom daily solutions
Reference Systems
• Precise Orbits• Reference Frames (ITRF and
SNARF)• Earth orientation parameters• Global Plate Motions and other
geophysical effects
You also need Global Tracking Systems for:
NASA Global GPS Network (GGN)Operated by JPL and UNAVCO – get products from the IGS
Reference Frames – ITRF/SNARF
Standard North American Reference Frame (SNARF)
- UNAVCO SNARF Working Group, Geoff Blewitt, Chair
Will provide an improved reference frame that accurately defines the precise coordinates and time evolution of a set of stations representing "stable North America."
ITRF 2000 Velocities (left) compared to a N.America-fixed Reference frame (WUSA, SAO, right)
Permanent Stations
Why Permanent Stations?
1. Improved precision and ability to assess precision- Longer time series- Tendency to invest in better monuments- Better able to characterize error sources
2. Measure transient phenomena- Earthquakes (co-seismic and high-rate), post-seismic,
interseismic - Volcano deformation- Subduction zone aseismic transients- Hydrologic signals- Post-glacial rebound
3. Improved reference frame4. Essential for orbits and clocks5. Economy
- Processing, data handling automated- Fewer personnel in field
6. Synergism with other applications (e.g. ATM, Surveying)
Global Plate Tectonics
Global GPS data are used to construct plate tectonic and strain rate modelsExample: REVEL-2000 from Sella and others, 2002.
Other plate motionModels have been determined from geology and seismology (Nuvel1A) and hot spot tracks (HS3).
UNAVCOPlate Motion Calculator
Also see NGS website for coordinate transformation tool.
Regional Plate Boundary Deformation
Finite Element Model
Observed GPS Velocity Field
Viscosity
L. Flesch and B. Holt
Deformation In the Plate Interior
Horizontal and Vertical Motions from Glacial Isostatic Adjustment
Stable North American Reference Frame (SNARF)
Permanent Stations
Tectonic
Signals
Basin and Range, Yellowstone U. of Utah, Caltech, Harvard SAO
Example of fairly linear motions(~2 to 3 mm/year)
Coseismic and Postseismic deformations for Parkfield 2004 earthquake.
EarthQuake Transients
P067
P278 P576 P526P295
Non-Tectonic Signals
Hydrologic
(non-tectonic
time-dependent signals)
Example from
the Salt Lake Basin
+- 3 cm vertical annual
Signals from spring runoff
(U. Utah)
GPS Seismology
High rate Kinematic GPS….1 hz GPS “seismogram” compared with seismometer, Denali EQ. Bock, 2004.
Reasons to look atHigh rate GPS EQs:
-GPS directly measures displacement (not velocity or acceleration)
-GPS does not clip
…but GPS is considerably less sensitive than a seismometer
EarthScope Instrumentation
• 3.2 km borehole into the San Andreas Fault
• 875 permanent GPS stations• Up to 174 borehole strainmeters • 5 laser strainmeters• 39 Permanent seismic stations
• 400 transportable seismic stations occupying 2000 sites
• 30 magneto-telluric systems• 100 campaign GPS stations• 2400 campaign seismic stations
PBO Permanent Stations
Rocky Mountain
Permanent GPS Stations
Making Stable Monuments –Different options depending on cost, geology, permits
Campaign GPS
EarthScope Campaign GPS
28 Portable Campaign GPS instruments and ancillary equipment purchased and ready for deployment.
72 Portable Campaign GPS instruments and ancillary equipment purchased in FY06.
Rio Grande Rift 5-year proposal funded through ES science
30 instrument Cascadia ETS Campaign for summer/fall 2005 (underway)
Campaign GPS
Come see the new EarthScope/PBO GPS gear in the poster session!
Topcon GB-1000Tech 2000 mast
PBO Campaign – ETS Cascadia
Cascadia Episodic Tremor and Slip Event Principal Investigator (PI): Ken Creager, Dan Johnson & Rick Bennett
UNAVCO staff: Freddy Blume (PBO Project Manager) & Nicole Feldl
Photo Location: Clallam Bay, Washington
30 Portable GPS Systems deployed
EarthScope Operational Status
Shown are PBO GPS Stations with data available from the UNAVCO Archive
GPS Data Flow and Access
The user will get raw data,Solution time series and velocity vectors
Borehole Strainmeters & Seismometers
Long-baseline Laser Strainmeters
Borehole Strainmeter Data Processing
0
1 105
2 105
3 105
4 105
5 105
04-Jan-1 04-Apr-1 04-Jul-1 04-Oct-1 05-Jan-1
Time
0
4000
8000
2004-Jun-24 2004-Jul-1 2004-Jul-8 2004-Jul-15 2004-Jul-22
ST
RA
IN (
CO
UN
TS
)
Time
• BSM Data Analyst: Kathleen Hodgkinson
• First Level 0 data: June 2005
• Pre-processing:– Decimate, linearize, remove tidal & borehole effects– Determine data edits using initial corrections
• Processing:– Edit raw data for outliers, offsets, etc.– Remove borehole trends– Generate tidal correction– Compute areal and shear strain– Convert to XML
• First Level 2 products: Sep 2005
• Similar products from LSM (SIO)
Strainmeter Data Flow and Access
GEO-EARTHSCOPE
EarthScope Imagery and Geochronology
“The EarthScope program invites proposals that include the acquisition of aerial and satellite imagery and geochronology that will examine the strain field beyond the decade time scales available from the PBO geodetic instrumentation.
A goal of EarthScope is the improved understanding of the tectonic evolution of the North American continent. Identifying and understanding deformation rates in all tectonic regimes is critical to reaching that goal.
Proposals should indicate how the imagery or geochronology will contribute to the success of EarthScope.”
2005 NSF EarthScope Announcement of Opportunity
GEO-EarthScope Possibilities
1. Airborne LiDAR image of the San Andreas fault. Courtesy of Ken Hudnut, USGS.2. InSAR image of the Hector Mine earthquake. Courtesy of Howard Zebker, Stanford.3. Ground Control using UNAVCO GPS receiver being deployed on the San Andreas fault to support
an airborne LiDAR survey. Photo courtesy of Francine Coloma, NSIDC.4. Geocronology associated paleoseismology study site on the San Andreas fault near Wrightwood, CA. 5. AMS Lawrence Livermore Accelerator Mass Spectrometer
1.
2.3.
4.
5.
Contact: Dr. David Phillips, UNAVCO/PBO Geo-EarthScope Project Manager
UNAVCO Support
UNAVCO Support Requests
• Permanent Stations
• Semi-permanent Stations
• Campaign Surveys
• GeoEarthScope
Come to UNAVCO
for help with your project
from proposal planning to
project implementation!
For more information…
http://pbo.unavco.orgwww.earthscope.org