BackForwardInstrument:  TIDI  

Instrument details
Acronym TIDI
Full name TIMED Doppler Interferometer
Purpose Solar-terrestrial interactions - Wind measurement in the mesosphere and lower thermosphere
Short description Fabry-Perot interferometer for fine spectral analysis (resolution 0.002 nm) in four oxygen bands (557.7, 630.0, 732.0 and 844.6 nm) to measure the Doppler effect due to wind
Background Follow-on of HRDI flown on UARS
Scanning Technique Limb sounding in four azimuth directions: ± 45° fore- and aft- the direction of the satellite motion. The four sequential measurements are taken at 750 km intervals along track
Resolution Vertical resolution from 2.5 km in the mesosphere to 25 km in the thermosphere; altitude range: 60-300 km
Coverage / Cycle Global coverage every day for cells of 800 km average
Mass 42 kg Power 20 W Data Rate 2.5 kbps


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2002 to 2024
Last update: 2021-11-27
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
  • Limb sounders
  • Limb sounder
WIGOS Subcomponents
  • Subcomponent 1
  • UV/VIS/NIR sounders, nadir and limb
  • UV/VIS/NIR scanning limb sounder
  • Subcomponent 2
  • UV/VIS/NIR/IR/MW limb sounders
  • UV/VIS/NIR/IR/MW scanning limb sounder
Mission objectives
Primary mission objectives
  • Wind (horizontal)
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
Atmospheric temperature4 - fairLimited to high atmosphere.NIR limb sounding by emission in the O2 A-band around 760 nm. Used for the thermosphere
Wind (horizontal)*4 - fairLimited to high atmosphere.VIS and NIR very-high resolution limb spectrometry. Doppler analysis of oxygen emission lines