BackForwardInstrument:  ACRIM-III 

Instrument details
Full name Active Cavity Radiometer Irradiance Monitoring - III
Purpose Total solar irradiance monitoring
Short description Assemblage of 3 active cavity radiometers, spectral range 0.15-5.0 µm
Background Evolution of ACRIM-I flown on SMM and ACRIM-II flown on UARS.
Scanning Technique Sun pointing during orbital movement, data sampled each 2 min
Resolution N/A
Coverage / Cycle One measurement after integration on all data taken during the diurnal orbit arc; thus 100 min
Mass 13 kg Power 10 W Data Rate 600 bps


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2000 to 2013
Last update: 2022-07-25
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*3 - highNo specific limitation.TSI over the range from UV to MWIR