Ann Chen

I am currently a PHD student in Department of Geophysics. I joined the Stanford Radar Interferometry Group in fall 2008.

Phase measurements from interferometric synthetic aperture radar (InSAR) can potentially measure centimetre-scale changes in deformation over timespans of days to years. At present, I am using the Repeat Orbit Interferometry Package (ROI_PAC) to process InSAR data from spaceborne synthetic aperture radar instruments like the European Remote-Sensing Satellite (ERS) and the Advanced Land Observation Satellite (ALOS). The L-band ALOS data can be further used to study effects of the Earth's atmosphere and ionosphere on InSAR data. The interferograms generated from ALOS data show the phase changes that might be caused by the atmosphere or ionosphere. With Global Positioning System (GPS) data in hand, I hope to measure the electron density in the ionosphere on a given day based on ionospheric delay estimation with dual-frequency measurements. Comparing the interferograms and the electron densities of these days, I am trying to distinguish between the ionosphere's effects and atmospheric effect.

The different colors in the figure shows the phase changes that are caused by effects of atmosphere and ionosphere. (These are mainly due to the atmosphere, probably.)