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Ocean Surface Topography from Space
The Application of Multiple Satellite Radar Altimetry Data Sets to Inland Surface Water Projects
Charon Birkett
(University of Maryland)

David Bjerklie
(United States Geological Survey)
Matthew Rodell
(NASA/Goddard Space Flight Center)
Image (left): This image shows the orbital path (depicted by series of points) of the Jason-1 satelite is shown in this image. The base map image of Lake Michigan was taken in 1990 by Landsat 5. Image (right): This image shows the relative lake height variations computed from TOPEX/POSEIDON (T/P) and Jason-1 altimetry with respect to a 10 year mean level derived from T/P altimeter observations.
Larger image with caption


This effort explores several inland water investigations using archival (T/P, ERS-1, ERS-2), current (Jason-1, GFO, ENVISAT) and future Ocean Surface Topography Mission (OSTM) mission data. The main science focus is on river dynamics, the use of lakes as proxy indicators of climate change, and the forecasting of drought/flood episodes in remote regions. A multi-altimeter approach provides a global outlook, combining the temporal and spatial resolution merits of each instrument, while each series (NASA/CNES or ESA) offers 15 to 20 years of observation. The utilization of multiple data sets is critical, seeking refined radar echo interpretation and atmospheric correction methods to improve measurement quality. Results from this work will feed directly into a USDA-funded near real time operations program that monitors large lakes and reservoirs around the world for irrigation resource concerns. The main objectives of this program are:

  1. To examine the overall performance of the OSTM radar altimeter over inland water targets.
  2. To refine echo interpretation and data evaluation methods to improve elevation accuracy and target resolution.
  3. To examine the merits and problems inherent in combining the NASA/CNES/ESA/NRL data sets,
  4. To undertake 3 science investigations,
    1. Evaluate the contribution of satellite radar altimetry to the determination of river discharge and river dynamics.
    2. Search for and interpret the correlations between observed lake/reservoir/river stage variations over a 20 year period and climatic indices such as ENSO and NAO. The long-term goals here are the evaluation of regional vulnerability to drought and floods.
    3. Determine GRACE volume storage changes and correlate the results with altimetric lake and tributary stage variations.

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