WInSAR Highlights for Fringe
 InSAR Workshop Report with hi-res figures
 InSAR Workshop Report
 UAVSAR CDR Powerpoint
 Correlation corrections on Antarctic data
 Titan's surface as observed from the 15-FEB-05 pass of the Cassini spacecraft radar This is the second radar image of Titan from Cassini.
 First view of the surface of Titan from the Cassini radar Titan is the largest moon of Saturn, and is covered by a dense atmosphere making the surface almost impossible tro see without an imaging radar instrument.
 Land subsidence in Las Vegas, Nevada Falk's paper
 Glacial movement of the Petermann Glacier, Greenland
 Volcano inflation (simulated) of Mt. Kilauea on the big island of Hawaii
 Earthquake deformation from the Landers earthquake, California
 Atmospheric water content from ERS interferometry
 Sjonni's paper on solution for subsurface deformation at Frenandina volcano, Galapagos, from ERS interferometry
 Two-dimensional phase unwrapping using network flow techniques
 Large and small versions of inverse solutions for slip distribution from the Hector Mine earthquake of 16 October 1999

• Prof. Howard Zebker
• Noah Bechor
• Ana Bertrán Ortiz
• Fayaz Onn
• Shadi Oveisgharan
• Piyush Shanker Agram
• Lauren Wye
• Sang-Ho Yun

• Falk Amelung
• Sarah Colclough
• Margrit Gelautz
• Ramon Hanssen
• John Lin
• Shachak Pe'eri

Science applications
• Crustal Deformation from Earthquakes
  Our emphasis here is on i) detecting inter-seismic and potentially pre-seismic transient strains, which remain elusive and raise a major challenge to our understanding of the earth, and ii) modeling faulting and crustal rheology from vector co- and post-seismic displacement maps, which complement conventional seismological and geodetic measurements. Sjonni Jonsson has analyzed this radar interferogram of the Hector Mine earthquake
• Volcanological Studies
  Deformation is also important in understanding volcanic processes. Our work here includes i) modeling magma migration from the spatial and temporal extent of deformation, ii) quantifying pressure changes at depth resulting from magma intrusion beneath volcanic edifices, and iii) analyzing the spatial extent of new material deposited during eruptions. Sjonni also has produced and modeled deformation at Sierra Negra in the Galapagos Islands.
• Earth's polar regions and the world's climate
  Ice sheets and glaciers in the Earth's polar regions both control and reflect changes in the world climate. InSAR allows us to investigate the mass balance, or the accumulation and loss of ice, in these remote areas. Weber Hoen's thesis examines how InSAR correlation measurements help us estimate ice accumulation rates worldwide. Here is a sample accumulation map, and we need to apply this method to the full Antarctic continent to understand global warming or cooling.
• Other studies of ground subsidence
  Our group is pioneering other new applications for InSAR. We have found these data to be useful for studying many geophysical phenomena of strong scientific value and societal benefit, such as the study and management of groundwater aquifer systems. Joern Hoffmann has concentrated on the use of InSAR to better model the flow of water underground (figure here) . Other fields under investigation include landslides, floods, oil extraction, and coastal erosion.
• Mapping the surfaces of planets and moons in our Solar System
  Leif Harcke uses the Arecibo Observatory in Puerto Rico, the NASA Deep Space Facility, and the Very Large Array in New Mexico as powerful radar systems to map the surfaces of solar system objects. We have studied Mercury, Mars, and the Galilean satelltes of Jupiter using these instruments. Here is a sample observational plan.
  
  Signal processing, design, and analysis
• Phase Unwrapping
  Phase unwrapping is a multidimensional signal processing technique that permits unambiguous interpretation of modulo-two pi phase measurements. Curtis Chen has recently developed a method based on maximum likelihood statistics and network flow models -- see his thesis and a sample figure.
  
• Atmospheric propagation and correction
  When radar signals travel through the atmosphere, they are delayed by the presence of water vapor. This corrupts the phase measurements in interferograms. Fayaz Onn is studying this phenomenon and how InSAR data may be improved through combination with GPS data. See a corrupted interferogram.
• Very high speed networking and data serving using Internet II
  One of our latest technical challenges is serving the science community with very large amounts of radar data via an online archive and distribution. We are now designing and implementing a system that catalogs 150 Gbytes of SAR data each day, and presents these to the world over a web-based interface. There are great challenges here in delivering data at gigabit speeds. Our group is using the new Internet II backbone (map) and developing special purpose data transfer codes to facilitate transfer of these data.

Student Opportunities

Research Assistantships
Most of our graduate students are supported by research assistantships, which generally means that initially you spend half of your time on coursework, and half on a research project. As you complete coursework, all of your time will be spent on research. In some cases projects are set by group needs, but in most cases we are able to define projects according to students' interests. We often have opportunities available in the group, so stop by and ask if you think that radar remote sensing and interferometry is an area that you'd like to work on for 5 years.

Skills and disciplines
Our work is broad in scope, and we expect students to be familiar with many technical areas. Since radar is an eclectic subject, as a group our students encompass many skills. Over the past few and next few years we have completed and anticipate theses comprised of original research in many areas, including:

Digital signal processing	Modeling crustal deformation
Digital image processing	Modeling groundwater flow
Electromagnetic wave propagation and scattering	Space geodesy
High-speed computing	Inverse modeling
High-speed networking

Open RA's and other opportunities

Undergraduate Research:

Our group sponsors undergraduate research both during the academic year and in the summer as part of the REU program. During the academic year this is most often in the form of directed research with course credit; the summer program involves a small stipend and on-campus housing. Interested students should contact group members for opportunities.

Summer 2004 Posters from our undergraduate students:

• Sandy Yu, "Analysis of Phoebe Rotation Rate and Spectral Bandwidth based on Cassini Satellite Data"
• Katherine Chen, "Correlation Estimation in SAR Interferograms"
• Abheek Banerjee, Rob Boyle, Wei Hsu, "WInSAR Data Archive and Server"
• Abheek Banerjee, Rob Boyle, Wei Hsu, "WInSAR Technical Details"

Weekly group meetings:

Wednesday, 12:00 p.m.
Mitchell Building
Room 372

Software

Downloadable software packages for radar and InSAR processing
--These are free, but please acknowledge their use in your research--
Documentation is included in some packages, but note that we do not support any of these products formally. You are free to use them but you are on your own as regards installation and usage.

• SNAPHU phase unwrapping code
• ROI InSAR processor source code for Linux

Computer resources

Our group barbecue in June 2002 was well attended. Here are view 1 and view 2 from our group dinner in June 2001. We also have a picture from a pizza party in the spring of 2000.

Contact: zebker_group@insar.stanford.edu