Repeat-pass multi-temporal interferometric SAR coherence variations with Amazon floodplain and lake habitats

Hahn Chul Jung, Doug Alsdorf

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We have analysed interferometric coherence variations in Japanese Earth Resources Satellite (JERS-1) L-band synthetic aperture radar (SAR) data at three central Amazon sites: Lake Balbina, Cabaliana and Solimões-Purús. Because radar pulse interactions with inundated vegetation typically follow a double-bounce travel path that returns energy to the antenna, coherence will vary with vegetation type as well as with physical and temporal baselines. Lake Balbina consists mostly of upland forests and inundated trunks of dead, leafless trees whereas Cabaliana and Solimões-Purús are dominated by flooded forests. Balbina has higher coherence values than either Cabaliana or Solimões-Purús probably because the dead, leafless trees support strong double-bounce returns. The mean coherences of flooded woodland are 0.28 in Balbina and 0.11 in both Cabaliana and Solimões-Purús. With increasing temporal baselines, flooded and nonflooded wetland habitats show a steadily decreasing trend in coherence values whereas terra-firme and especially open-water habitats have little variation and remain lower in value. Flooded and nonflooded wetland coherence varies with the season whereas terra-firme and open water do not have similarly evident seasonal variations. For example, flooded habitats in all three study regions show annual peaks in coherence values that are typically 0.02 greater than coherence values from temporal baselines 180 days later, yet open water shows no variation with time. Our findings suggest that, despite overall low coherence values, repeat-pass interferometric coherence of flooded habitats is capable of showing the annual periodicity of the Amazon flood wave.

Original languageEnglish
Pages (from-to)881-901
Number of pages21
JournalInternational Journal of Remote Sensing
Issue number4
Publication statusPublished - 2010 Apr

Bibliographical note

Funding Information:
Funding for this research was provided by the Terrestrial Hydrology Program and Solid Earth and Natural Hazards Program at the National Aeronautics and Space Administration (NASA). JERS-1 SAR data were provided by the National Space Development Agency of Japan (NASDA). This work was also supported by a Korean Science and Engineering Foundation Grant (No. C00131).

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)


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