A review of terrestrial radar interferometry for measuring surface change in the geosciences

Abstract

This paper presents a review of the current state of the art in the use of terrestrial radar interferometry for the detection of surface changes related to mass movement. Different hardware‐types and acquisition concepts are described, which use either real or synthetic aperture for radar image formation. We present approaches for data processing procedures, paying special attention to the separation of high resolution displacement information from atmospheric phase variations. Recent case studies are used to illustrate applications in terrestrial radar interferometry for change detection. Applications range from detection and quantification of very slow moving (millimeters to centimeters per year) displacements in rock walls from repeat monitoring, to rapid processes resulting in fast displacements (~50 m/yr) acquired during single measurement campaigns with durations of only a few hours. Fast and episodic acting processes such as rockfall and snow avalanches can be assessed qualitatively in the spatial domain by mapping decorrelation caused by those processes. A concluding guide to best practice outlines the necessary preconditions that have to be fulfilled for successful application of the technique, as well as in areas characterized by rapid decorrelation. Empirical data from a Ku‐band sensor show the range of temporal decorrelation of different surfaces after more than two years for rock‐surfaces and after a few seconds to minutes in vegetated areas during windy conditions. The examples show that the displacement field can be measured for landslides in dense grassland, ice surfaces on flowing glaciers and snowpack creep. Copyright © 2014 John Wiley & Sons, Ltd.

Polarimetric Calibration of the Ku-Band Advanced Polarimetric Radar Interferometer

“…An alternative imaging approach is to scan a fan beam by rotating a large antenna [27], [29]. This imaging method has been called type II in [30]. This configuration has certain advantages over groundbased synthetic aperture systems [31] of comparable rail length:…”

“…To process them, it is necessary to understand the data acquisition and correct several effects specific to KAPRI. For this purpose a signal model for type II [30] radar data using the deramp-on-receive FMCW architecture [46] is introduced. Consider a coordinate system having its origin at the location of a radar, as depicted in Figure 1.…”

Multi-method observation and analysis of a tsunami caused by glacier calving

“…A terrestrial radar interferometer (TRI; Caduff et al, 2014) was used in summer 2014 to measure ice flow velocities of the terminus area. The TRI system was a Gamma Portable Radar Interferometer (GPRI), a Ku-band real aperture radar with one transmitter and two receiver antennas.…”

Monitoring Alpine glacier surface deformations with GB-SAR

“…Although this novel technique is able to provide only a partial estimate of the actual ice flow, displacement maps of glaciers of some square kilometres in size, from 3-4 km distances and entirely remotely sensed, can be obtained. Exhaustive reviews of this state of the art technique, the different instrumentation available, and the performances thereof, are available in Caduff et al (2015) and Monserrat, Crosetto, and Luzi (2014). Especially in the case of alpine glaciers, which are particularly affected by cryosphere changes due to global warming (Deline et al 2012), research and monitoring can largely benefit from the spatial and temporal sampling provided by terrestrial radar surveys.…”