BackForwardInstrument:  TGRS (COSMIC-2) 

Instrument details
Acronym TGRS (COSMIC-2)
Full name TriG (Tri-GNSS) GNSS Radio Occultation System
Purpose Temperature/humidity sounding with highest vertical resolution, space weather
Short description

Measuring the phase delay due to refraction during occultation between GPS and LEO. For TEC the accuracy is < 3 TECU. 
Background

New development
Scanning Technique

Neutral atmosphere : Limb scanning from 90 km with digital beam steering (medium gain). 130° azimuth in fore and aft directions. Space weather: Zenith to limb scanning from 550 km (low gain). 140° azimuth in fore and aft directions.
Resolution About 200 km horizontal, 0.5 km vertical
Coverage / Cycle 3 GNSS constellations possible to track, only 2 actually tracked. About 5000 soundings/day (with 6 satellites) - Average spacing 320 km - Global coverage (300 km spacing) in 24 h
Mass 6 kg Power 65 W Data Rate 100 kbps

 

Providing Agency NASA
Instrument Maturity Backed by strong heritage
Utilization Period: 2020 to 2026
Last update: 2024-04-15
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
  • GNSS radio-occultation
WIGOS Subcomponents
  • Subcomponent 1
  • GNSS radio occultation (basic constellation)
  • GNSS radio occultation sounder (basic constellation)
  • Subcomponent 2
  • Magnetospheric energetic particles and magnetometers
  • Ionospheric total electron content sensor [at LEO and cross magnetosphere]
  • Ionospheric electron density sensor [in LEO and cross magnetosphere]
Mission objectives
Primary mission objectives
  • Atmospheric temperature
  • Height of the top of PBL
  • Height of the tropopause
  • Ionospheric Total Electron Content (TEC)
  • Specific humidity
  • Temperature of the tropopause
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 temperature*1 - primaryInaccurate in low troposphere.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite
Geoid4 - fairHighly indirect.Radio-occultation processing implies precise orbitography. Geoid derived from multi-temporal analysis
Gravity field5 - marginalHighly indirect.Radio-occultation processing implies precise orbitography. Gravity field derived from multi-temporal analysis
Height of the top of PBL*1 - primaryNo specific limitation.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite. PBL top measured as discontinuity of the refraction index
Height of the tropopause*1 - primaryNo specific limitation.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite. Tropopause height measured as discontinuity of the refraction index
Specific humidity*2 - very highInaccurate in high troposphere.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite
Temperature of the tropopause*1 - primaryNo specific limitation.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite
Atmospheric density1 - primaryNo specific limitation.Measuring atmospheric density
Electron Density1 - primaryNo specific limitation.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite
Ionospheric Total Electron Content (TEC)*2 - very highNo specific limitation.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite
Ionospheric Scintillation4 - fairNo specific limitation.Flown in a satellite cluster. Two directional antennas, one GNSS system tracked, about 500 soundings/day per satellite