An analysis of terrain properties and the location of surface scatterers from persistent scatterer interferometry

Standard interferometry poses a challenge in heavily vegetated areas due to decorrelation of the radar signal. To alleviate this problem, we implement StaMPS, a persistent scatterer (PS) technique, to obtain a more spatially complete signal in the Cascade Range of the Pacific Northwest. In addition to comparing the spatial extent of the signal from standard Interferometric Synthetic Aperture Radar (InSAR) and StaMPS, we further analyze the selection of scatterers over several terrain types in the Cascades, and systematically vary StaMPS parameters to minimize the selection of false positives and negatives. Utilizing the best parameters, we correlate the location of persistent scatterers to geologic units, and vegetation density derived from Light Detection and Ranging (LiDAR) data. Our findings indicate that persistent scatterers most frequently occur on young, rough basaltic to andesitic lava flows and to a lesser extent on older, reworked basaltic andesitic lava flows exposed as boulder fields in the forests. Very few or no scatterers were found over water, permanent snowfields, evergreen forest, or unconsolidated pyroclastics. Over 90% of the scatterers are located in areas with no or very sparse vegetation cover. Based on surface roughness and the percentage of bare earth within the radar footprint, we are able to predict where PS InSAR is most likely to be successful on natural terrains.