Evaluation of RADARSAT-2 Acquisition Modes for Wetland Monitoring Applications

Interferometric synthetic aperture radar (InSAR) techniques can monitor water-level changes in wetlands with suitable coherence. RADARSAT-2 has many beam modes with varying system parameters to satisfy a wide range of applications. During data acquisition the SAR signals are digitized using eight-bit analog-to-digital converters followed by block adaptive quantization (BAQ) coding. Most RADARSAT-2 beam modes use three-bit BAQ but some modes use two-bit BAQ to accommodate larger data sets, including the wide multilook fine and wide ultrafine modes. These modes are attractive for surface monitoring applications due to good resolution over a wide swath. The two-bit BAQ can have signal saturation due to the smaller dynamic range and an increased phase noise. The Everglades National Park (ENP) has been used for numerous InSAR investigations of water level monitoring. This study describes the results of an evaluation of RADARSAT-2 products from different modes for the monitoring of water-level changes and flooded vegetation in ENP. The objective was to evaluate products from a variety of beam modes for wetland monitoring applications and subsequent unwrapping of the interferograms for water level estimation. The results show that wide-swath high-resolution modes are suitable for InSAR applications due to adequate coherence and high backscatter intensity.