BackForwardInstrument:  SSIM 

Instrument details
Acronym SSIM
Full name Solar Spectral Irradiance Monitor
Purpose Spectral solar irradiance in UV/VIS/NIR/SWIR
Short description Prism spectrometer for spectral irradiance: range 165-1650 nm, split in three bands: 165-320 nm (resolution 1 nm), 285-700 nm (resolution 1 nm) and 650-1650 nm (resolution 8 nm). Absolute accuracy: 3% from 165 to 240 nm and 2% from 240 to 1650 nm. There are 5191 channels in total.
Background New development
Scanning Technique Sun pointing during orbital movement, data sampled every 2 min
Resolution N/A
Coverage / Cycle One measurement after integration of all data taken during the orbit; thus 100 min
Mass Power Data Rate


Providing Agency CMA
Instrument Maturity Flown on operational programme
Utilization Period: 2021 to 2035
Last update: 2024-01-29
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
  • Solar irradiance monitor
WIGOS Subcomponents
  • Subcomponent 1
  • Absolutely calibrated broadband radiometers, and TSI and SSI radiometers
  • TSI and SSI radiometers (for solar irradiance)
Mission objectives
Primary mission objectives
  • Downward short-wave irradiance at TOA
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
Downward short-wave irradiance at TOA*5 - marginalNo specific limitation.Spectral irradiance stretching to SWIR