Polarimetric synthetic aperture radar (SAR) and geodynamic applications: An overview of a new Earth system observation concept

Abstract

Space-borne Earth observation technique is one of the most cost effective and rapidly advancing Earth science technological research tools today and the micro-wave radar applications have been leading the discipline. The new Earth observation satellites ENVISAT (launched on March 1 2002, specifically for Earth environment observation), ALOS (planned for launching in 2004 and stands for Advanced Land Observation Satellite), and RADARSAT-II (planned for lauching in 2004) all have synthetic aperture radar (SAR) onboard, which all have partial or fully polarimetric imaging capabilities. In addition to the radar altimeter and scatterometer, these new types of polarimetric imaging radars are opening up completely new possibilities in Earth system science research. The main advantage of a SAR system is the all weather imaging capability without Sun light and the newly developed interferometric capabilities, utilizing the phase information in SAR data further extends the observation capabilities of directional surface covers and neotectonic surface displacements. In addition, if one can utilize the newly available multiple frequency polarimetric information, the new generation of spaceborne SAR systems is the future research tool for Earth observation and global environmental, change monitoring investigation. In preparation of the up-coming new generation of satellites ENVISAT, ALOS, and RADARSAT-II, the Korean scientists and engineers planned the PACRIM-II experiment with NASA(JPL) AIRSAR/MASTER team and carried out multi-disciplinary experiments in the fall of 2000, followed by extensive ground truth field work. The main sensors being utilized included the fully polarimetric SAR systems capable of routine imaging as well as both coss- and along-track interferometry, selectively in three frequencies (C-, L-, and P-bands). The newly added MASTER simulator was a hyperspectral optical imaging system with spectral windows duplicating the MODIS and ASTER multispectral imaging systems. The participating science and engineering disciplines include EM engineering, communication technology, image processing, meteorology, forestry, archeology, geology, environment, natural disaster monitoring and management, geohydrology, agriculture, fishery, coastal changes and oceanography. The geodynamic applications being investigated with the multiple frequency fully polarimetric AIRSAR data include precise generation of digital elevation model (DEM), development of multi-temporal differential crosstrack SAR interferometry, and surface geological mapping without look-direction bias.