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Ocean Surface Topography from Space
Application of Multiple Satellite Radar Altimetry Data Sets to Serve Inland Surface Water Projects


Charon Birkett - (University of Maryland)

  David Bjerklie
Claudia Carabajal
(United States Geological Survey, Water Resources Division, Connecticut District)
(Sigma Space Corporation @ NASA/GSFC, NASA Goddard Space Flight Center, NASA/GSFC Planetary Geodynamics Laboratory)
  Ben Gouweleeuw
Eric Wolanski
Benjamin Zaitchik
Curt Reynolds
(CSIRO, Land and Water )
(James Cook University, TropWater ACTFR )
(Johns Hopkins University, Department of Earth and Planetary Sciences)


Satellite radar altimetry is a valuable tool in providing surface height (stage) measurements of inland water targets. The technique is being utilized in various interdisciplinary research and operational-based projects, in many cases providing new datasets for regions where traditional gauge data is sparse. Multiple radar altimeter data sets are now available from NASA and other agencies. While tandem operating periods or synergistic missions offer increased spatial resolution over river basins and wetlands, the provision of continuous (current and archival) data sets transfers lake height measurements into long-term proxy indicators of climate change.

This proposal seeks to explore several inland water science investigations using archival (T/P, Jason-1, ERS), current (Jason-2/OSTM, ENVISAT) and future (Jason-3, SARAL, Sentinel-3) radar altimeter data. The science focus is on river and wetland dynamics and the utilization of lake levels as a proxy indicator of climate change. A multi-altimeter approach provides a more global outlook, combining the temporal and spatial resolution merits of each instrument, while the exploration of additional synergistic data such as NASA's ICESat-1 mission offers a multi-sensor approach for the determination of river discharge. A strong instrument performance and validation theme runs throughout the proposed program with respect to ongoing and future missions. This includes addressing the problems inherent in the merger of multiple datasets, and seeking refined radar echo interpretation methods to improve target detection and elevation accuracy. Technical results will feed directly into a near real time NASA/USDA operational program that monitors large lakes and reservoirs around the world for drought and water resources issues.

The main objectives are thus:

  1. To focus on the performance of NASA/CNES Jason-2/OSTM and Jason-3 altimeter instruments over inland water targets. To develop data evaluation methods that maximize accuracy and resolution, and to provide feedback to the SWT community and to the NASA/USDA lake monitoring program.
  2. To investigate the dynamics of the Yukon River. To test radar and lidar altimeter capabilities for measuring hydraulic parameters such as height and along-channel water-surface slope, and when combined with water-surface width (from imagery), for estimating the capability of determining river discharge. The identification of freeze/thaw periods, the effects of ice on the radar and lidar signals, and the seasonal and inter-annual dynamics of the river will be under investigation.
  3. To examine the correlations between observed lake height variations and climatic indices (e.g. ENSO, NAO). The long-term goals are the evaluation of regional vulnerability to droughts and floods and the utilization of near-real time elevation data.
  4. To investigate the application of radar altimetry within three Pilot Projects
    1. The Balonne River, southern Queensland, regarding issues relating to water storage management in the light of regional drought and flood events.
    2. The Sudd wetlands, Africa, regarding drought susceptibility in the Nile basin and wetland water storage considerations.
    3. The Usangu wetlands, Africa, regarding conservation and ecology issues and the role of vegetation in the regional water budget.

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