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Surface Water and Ocean Topography - SWOT

Amazon River
Amazon River
Mission Science

Both the surface water hydrology and ocean surface topography communities recognize the importance of wide-swath altimetry for its capability of acquiring high-resolution elevation measurements.

  • Hydrology: Provide a global inventory of all terrestrial water bodies whose surface area exceeds 250 meters by 250 meters (lakes, reservoirs, wetlands) and rivers whose width exceeds 100 meters (rivers).
    • Measure the global storage change in fresh water bodies at sub-monthly, seasonal, and annual time scales.
    • Estimate the global change in river discharge at sub-monthly, seasonal, and annual time scales.
  • Oceanography: Characterize the ocean mesoscale and sub-mesoscale circulation at spatial resolutions of 15 kilometers and greater.

Mission Architecture

Artists concept of SWOT KaRIN instrument.
Artists concept of SWOT KaRIN instrument.
SWOT’s Ka-band Radar Interferometer (KaRIn) will determine ocean and surface water topography. A Jason-class altimeter beam will be located between these swaths.
  • KaRIn interferometric system with two 50-kilometer swaths will produce water heights and co-registered all-weather imagery
  • KaRIn will be configured to transmit from one side and receive on antennas at both sides
  • On-board interferometric radar image processing over the ocean (500m^2 resolution) for data volume reduction
  • Fast-sampling orbit (approximately first six months): 857 kilometer altitude, 77.6º inclination, 1 day repeat
  • Science orbit (nominally three years): 891 kilometer altitude, 77.6º inclination, 21 day repeat
  • Target Launch Readiness: April 2021

Altimeter System

Orbit HeightOrbit TypeSwathFrequencyHeight PrecisionSpatial ResolutionInstrument
SWOT857-890 km22-day repeat
78 Deg Inclination
120 kmKa-band~1 cm @ 1 km resolution<100 m imagingInterferometer
OSTM/Jason-21336 km10-day repeat
66 Deg Inclination
NAKu-band2 cm6.2 km along-track; 300 km cross-trackNadir Altimeter

Below are various technology presentations in Power Point format that relate to the SWOT mission.

Year: 2006
  • Vivien Enjolras, "Altimetry Waveform Data and SRTM to Retrieve River Characteristics." Venice 2006. (Link)

  • Vivien Enjolras, "Performance Study of Interferometric Radar Altimeters." Venice 2006. (Link)

  • Vivien Enjolras, "The WatER Mission in Europe: How Can It Help Science?." Venice 2006. (Link)

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