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Water level changes in a large Amazon lake measured with spaceborne radar interferometry and altimetry
Author(s) -
Alsdorf Doug,
Birkett Charon,
Dunne Thomas,
Melack John,
Hess Laura
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl012962
Subject(s) - altimeter , geology , remote sensing , geodetic datum , interferometry , radar , geodesy , water level , synthetic aperture radar , volume (thermodynamics) , ocean surface topography , radar imaging , tide gauge , sea level , oceanography , geography , optics , cartography , quantum mechanics , telecommunications , physics , computer science
We demonstrate that interferometric processing of JERS‐1 SAR data over an Amazon lake containing ∼1500 islands yields centimeter‐scale changes in the height of the water surface from February 14 to March 30, 1997. For the method to work, we qualitatively find that inundation of about one or two leafless trees per 25 m² multi‐look SAR pixel is sufficient to return the radar pulse to the side‐looking antenna. Validation is provided by multi‐temporal TOPEX‐POSEIDON altimetry profiles, which directly measure surface heights relative to a fixed datum. Because SAR provides an image, the water height changes (∼12 cm) can be converted to a net volume measurement (280 million m³) over the 44 days separating the JERS‐1 acquisitions. Compared to historical gauge records, removal of this volume from the lake required a ∼50% greater flow.