BackForwardInstrument:  SHIOSAI 

Instrument details
Full name SAR Height Imaging Oceanic Sensor with Advanced Interferometry
Purpose Large-swath altimetry for local ocean circulation including sea state
Short description Equipped with two parallel antennas to implement interferometry. Frequency in X-band (about 9.5 GHz)
Background New development
Scanning Technique Two parallel swaths, 80-km each, total 160 km
Resolution 5 km
Coverage / Cycle Latitute coverage from about 50°S to 50°N in one week
Mass Power Data Rate


Providing Agency JAXA
Instrument Maturity Demonstration pending
Utilization Period: 2024 to 2027
Last update: 2021-08-30
Detailed characteristics
Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Instrument classification
  • Earth observation instrument
  • Active and radio-occultation sensor
  • Radar altimeter
WIGOS Subcomponents
  • Subcomponent 1
  • Wide-swath radar altimeters, and high altitude, inclined, high-precision orbit altimeters
  • Wide-swath radar altimeter
  • Conventional radar altimeter
  • Subcomponent 2
  • Interferometric radar altimetry
  • Interferometric radar altimeter [for wide-swath]
  • Subcomponent 3
  • Radar and lidar for vegetation mapping
  • Wide-swath radar altimeter for vegetation mapping
Mission objectives
Primary mission objectives
  • Geoid
  • Ocean dynamic topography
  • Significant wave height
Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
Note: * Primary mission objective.
VariableRelevance for measuring this variableOperational limitationsExplanation
Coastal sea level (tide)1 - primaryInfrequent coverage.Single-frequency X-band radar altimeter with large swath for mapping
Geoid*2 - very highInfrequent coverage.. Long time series needed.Geoid derived from multi-temporal analysis of radar altimetry data
Gravity field4 - fairPartial information (geoid).Gravity field derived from multi-temporal analysis of radar altimetry data
Ocean dynamic topography*1 - primaryInfrequent coverage.. Long time for mapping.Single-frequency X-band radar altimeter with large swath for mapping
Significant wave height*1 - primaryInfrequent coverage.The large swath enables more frequent global coverage
Wind speed (near surface)4 - fairOver sea only.. Infrequent coverage.Improved coverage associated to better resolution, that implies better accuracy