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

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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

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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

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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

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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