SCEC Award Number 12096 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Independent assessment of the impact of atmospheric water vapor on InSAR time series
Investigator(s)
Name Organization
Rowena Lohman Cornell University
Other Participants William Barnhart (PhD student)
SCEC Priorities 1d, 1e, 2c SCEC Groups Geodesy, SDOT, Seismology
Report Due Date 03/15/2013 Date Report Submitted N/A
Project Abstract
 Interferometric Synthetic Aperture Radar (InSAR) and InSAR time series analysis are powerful tools for imaging continental surface deformation globally. In regions with many SAR acquisitions and favorable imaging characteristics, InSAR time series techniques are able to constrain time-averaged rates as low as 2-3 mm/yr over short spatial scales (<25km). The precision of measurements in individual interferograms, however, is impacted by several sources of noise, notably spatially correlated signal caused by path delays as the radar signal propagates through the stratified and turbulent atmosphere and ionosphere . In many instances, this noisy signal, termed the “wet delay,” may account for several centimeters of apparent deformation in the radar line-of-sight (LOS) over short spatial scales (<10km). Moreover, wet delay signals, like expected subsidence and uplift signals associated with interseismic deformation, are often spatially correlated with topography. We show that the use of independent satellite observations of precipitable water vapor can allow assessment of the significance of individual features in InSAR-based time series analyses.
Intellectual Merit This work contributes to SCEC's goals of generating maps of vertical and horizontal displacements from both GPS and InSAR.
Broader Impacts This work supports a female junior faculty member, as well as a graduate student.
Exemplary Figure Figure 3: (left) InSAR time series (black) from Figure 7 and displacements inferred from all 100 MODIS time series (gray). (right) InSAR time series (black) with 1-sigma confidence envelope (gray) determined from the MODIS time series in a-c.