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Kiyo Tomiyasu, Co-Seismic Slip, and the Krafla Volcano:
Reflections on InSAR and Earth Science
Paul A. RosenJet Propulsion Laboratory
California Institute of Technology
Special Session Honoring the Achievements of Kiyo Tomiyasu
IGARSS 2010Honolulu, Hawaii
Background
OutlineTrends in Interferometric SAR (InSAR) for Earth
Science
Geosynchronous InSAR Concept
Presentation of 90th Birthday Celebratory Plaque of Appreciation to Kiyo Tomiyasu from JPL
Interferometric SAR for Measuring Earth Surface Change
€
Δφ =4π
λ(ρ (t1) − ρ (t2)) =
4π
λΔρ change
t1t2
Δρchangeρ(t1)
ρ(t2)
t1 t2
Trends in Observational Techniques for Earth Science
Frequent sampling in time
Fine spatial resolution
Time series / PS analysis
Extraction of geophysical parameters automatically
Exploitation of data for rapid response to events
Anticipated mean access times
for upcoming systems
Interferogram stack
time
U
Mean Access Time (Day)
∞ 4 2 1.3 1
A multi-scale approach to InSAR time series analysis
Interferogram stack
time
U
A geophysical perspective on deformation tomography
Example: Northern Volcanic Zone, Iceland
M. Simons, E. Hetland, P. Muse, Y. N. Lin & C. DiCaprio
Motivation
Assume that in the future we will have:• Frequent repeats (short DT)• Good orbits with small baselines• Ubiquitous high coherence
Challenge for the future:• How to deal with O(103) interferograms• How to use Cd - Invert all pixels simultaneously?
1000 igrams x 1000 x 1000 pixels = 1 billion data• Computational tractability
Approach: MInTS = Multi-scale InSAR Time Series
1. Time domain: A generalized physical parameterization (GPS-like)
2. Space domain: Wavelets – use all data simultaneously
1. Interpolate unwrapping holes in each interferogram whereneeded (temporary)
2. Wavelet decomposition of each interferogram
For later weighting purposes, track relative extent to which each wavelet coefficient is associated with actual data versus interpolated data
3. Time series analysis on wavelet coefficients
Physical parameterization + splines for unknown signals - all constrained by weighted wavelet coefficients of observed interferograms
4. Recombine to get total deformation history
MInTS Methodology
Example: Iceland Northern Volcanic Zone – Instantaneous Velocity
Example: Iceland Northern Volcanic Zone – Instantaneous Velocity (nonlinear)
Summary: Iceland Northern Volcanic Zone – Instantaneous Velocity
MInTS gives us continuous time, but does not yet combine multiple LOS to get 3D displacements. For the moment, we adopt a simple 2D reconstruction approach on a profile and neglect any rift parallel motion along the profile. Note asymmetries.
Rift zone models compared to data
Geosynchronous SARAn approach to observing the evolution of Earth’s surface
A Geosynchronous Synthetic Aperture Radar;
for Tectonic Mapping, Disaster Management and Measurements of Vegetation and Soil
Moisture
IGARSS, Sydney, July 9–13, 2001
Søren N. Madsen, Wendy Edelstein, Leo D. DiDomenico
Jet Propulsion Laboratory, California Institute of Technology
John LaBrecqueNASA Headquarters
A Geosynchronous SAR Concept
16
Previous Work
- Tomiyasu K.:
“Synthetic Aperture Radar in Geosynchronous Orbit,” Dig. Int. IEEE Antennas and Propagation Symp., U. Maryland, 42–45, May 1978
“Synthetic Aperture Radar Imaging from an Inclined Geosynchronous Orbit,” IEEE Trans. Geosci. Remote Sens. GE-21(3), 324–328 (1983)
- Holt, B. & Hilland, J.
“Rapid-Repeat SAR Imaging of the Ocean Surface: Are Daily Observations Possible?” Johns Hopkins APL Technical Dig., 21(1), 162–169, 2000
A Geosynchronous SAR Concept
17
GeoSync SAR Orbit and Measurement Description
Orbit- 35789 km altitude (geosynchronous)- 60˚ inclination (not geostationary)- 1 day repeat
Instrument- L-band SAR- Continuous strip mapping, interferometric ScanSAR, or spotlight operation
- 30 m diameter antenna aperture (electronically scanned array)• Distributed T/R modules on membrane• Nadir pointed, all steering electronic (only ±8º required side to side)
- Radar and spacecraft bus integrated on inflatable/rigidizable structure- 5500 km accessible ground swath on either side of nadir- 100% instrument duty cycle (always in view of land)
A Geosynchronous SAR Concept
18
Operational Modes Highly Flexible
Operational modes- Stripmap SAR with 400 km swath width:
• 10 m resolution @ 4–5 looks• Suited for high-resolution mapping
- ScanSAR over 5500 km swaths on either side of nadir track:• 50 m @ 4–5 looks • Daily continental coverage
- Squint-scanned SAR (beam hops to +45˚, broadside, –45˚):• 3–D displacement mapping of extended areas in a single day • Useful for tectonic studies
- Spotlight SAR (beam dwells on single target area for long time):• High resolution in azimuth, semi-continuous coverage• Suitable for disaster management
- High resolution stepped frequency SAR (step frequency within 80 MHz band on successive passes then combine coherently to get high resolution without losing SNR or increasing data rate):• 2 m ground range resolution, 2m azimuth resolution at far range• 6-10 m resolution at near range
Data rates and volumes- Data rate 220 Mbits/sec per 20 MHz channel- 2.4 TB/day with nearly 100% instrument duty cycle
A Geosynchronous SAR Concept
19
GeoSync Instrument Concept
Telescoping booms (x2)
Horizontal booms (x12)
L-band RF membrane
antenna aperture
Thin-filmSolar Arrays
Spacecraft Bus
• L-band single-polarization (HH) SAR• 30m diameter antenna aperture• 65 KW peak transmit power• 724 kg total instrument mass• 28 KW DC instrument power
Propulsion Modules (x2)
A Geosynchronous SAR Concept
20
GeoSync Constellations & Coverage
Constellation of 10 satellites in 5 groups (2 satellites per “figure-8” ground track)- Most of populated parts of Earth visible nearly continuously- Max duration of gaps in coverage less than 2 hours for 90 % of surface- 3-D displacement accuracy for select target areas < 1 cm with 24 hours of observations
Maximum coverage gap Maximum 3D displacement error
Relative AccuracyMinutes
InnovationNew concepts for geosynchronous deformation
observations
New ideas in enabling technologies
Seismology from Space
Improving Earthquake Forecasting
Celebratory PlaqueTo
Kiyo Tomiyasu
With greatest appreciation on your ninetieth birthday for a lifetime of innovation in remote
sensing
Signed by Charles Elachi, Director
Jet Propulsion Laboratory