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Investigating the Performance of the Jason-2/OSTM Radar Altimeter Over Lakes and ReservoirsMany inland water investigations utilize archival and near-real time radar altimetry data to enable observation of the variation in surface water level. A multi-altimeter approach allows a more global outlook with improved spatial resolution, and combined long-term observations improve statistical analyses. Central to all programs is a performance assessment of each instrument. Here, we focus on data quantity and quality pertaining to the Poseidon-3 radar altimeter onboard the Jason-2/OSTM satellite.Utilizing an interim data set (IGDR), studies show that the new on-board DIODE/median and DIODE/DEM tracking modes are performing well, acquiring and maintaining the majority of lake and reservoir surfaces in varying terrains. The 20-Hz along-track resolution of the data, and particularly the availability of the range output from the ice-retracker algorithm, also improves the number of valid height measurements. Based on test-case lakes and reservoirs, output from the ice-retracker algorithm is also seen to have a clear advantage over the ocean-retracker having better height stability across calm and icy surfaces, a greater ability to gain coastline waters, and less sensitivity to loss of water surface when there is island contamination in the radar echo. Such on-board tracking and postprocessing retracking enables the lake waters to be quickly gained after coastline crossing. Values can range from <0.1 s to 2.5 s, but the majority of measurements are obtained in less than 0.4 s or <2.3 km from the coast. Validation exercises reveal that targets of 150 km2 surface area and 0.8 km width are able to be monitored offering greater potential to acquire lakes in the 100 C300 km2 size-category. Time series of height variations are also found to be accurate to 3 to 33 cm rms depending on target size and the presence of winter ice. These findings are an improvement over the IGDR/GDR results from the predecessor Jason-1 and TOPEX/Poseidon missions and can satisfy the accuracy requirements of both the science-related and operational lake study programs.
Document ID
20110015313
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Birkett, C. M.
(Maryland Univ. College Park, MD, United States)
Beckley, B.
(SGT, Inc. Greenbelt , MD, United States)
Date Acquired
August 25, 2013
Publication Date
August 1, 2010
Publication Information
Publication: Marine Geodesy. Special Issue: OSTM/Jason-2 Calibration/Validation
Publisher: Taylor and Francis
Volume: 33
Issue: Supplemet 1
ISSN: 0149-0419
Subject Category
Instrumentation And Photography
Report/Patent Number
GSFC.JA.4684.2011
Funding Number(s)
CONTRACT_GRANT: NNX08AM72G
CONTRACT_GRANT: NNX08AT88G
Distribution Limits
Public
Copyright
Other

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