BackForwardInstrument:  FSI 

Instrument details
Acronym FSI
Full name FORUM Sounding Instrument
Purpose To provide new insight into the planet’s radiation budget and how it is controlled. To measure the scattering of ice cloud at 20 um and the emissivity of snow/ice over the poles.
Short description Four-port double pendulum Fourier-Transform interferometer, to cover the range 100-1600 cm-1 (6.25-100 μm) with a spectral resolution of 0.5 cm-1 (unapodised). An embedded TIR imager centred at 10.5 μm with a bandwidth of 1.5 μm looking at the same scene as the interferometer acquires co-located images during the dwell time for detection of scene inhomogeneities. NedT of sounder 0.1K above 300 cm-1 and 0.2K for 200-300 cm-1.
Background New development
Scanning Technique Non-scanning. Step-and-stare acquisition along-track. FOV's of about 36 km x 36 km sampled at 100 km intervals. Inside the FOV there are a single 15-km IFOV of the interferometer and 60x60 0.75-km IFOV's of the embedded imager. The embedded imager collects at least 5 images over the FOV during a dwell time of 14 s.
Resolution Interferometer: 15 km; embedded imager; 0.75 km.
Coverage / Cycle The repeat cycle of the FORUM orbit is 29 days. Note only measurements at nadir are made.
Mass Power Data Rate

 

Providing Agency ESA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2027 to 2033
Last update: 2023-11-30
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
  • Passive optical radiometer or spectrometer
  • Cross-nadir infrared sounder, possibly including VIS channels
WIGOS Subcomponents
  • Subcomponent 1
  • IR hyperspectral sounders [in SSO]
  • IR hyperspectral sounder [in SSO]
Mission objectives
Primary mission objectives
  • Atmospheric temperature
  • Cloud ice
  • Cloud ice Total Column
  • Cloud ice effective radius
  • Height of the tropopause
  • Integrated Water Vapour (IWV)
  • Sea surface temperature
  • Specific humidity
  • Temperature of the tropopause
  • Upward long-wave irradiance at TOA
  • Upward spectral radiance at TOA
Evaluation of Measurements