BackForwardInstrument:  ALTIUS 

Instrument details
Acronym ALTIUS
Full name Atmospheric Limb Tracker for Investigation of the Upcoming Stratosphere
Purpose To measures high-vertical-resolution profiles above 15km of ozone and possibly other trace gases, and aerosol concentration, in the UT/LS.
Short description

Limb sounding spectrometer. Three independent imaging spectrometers operating in UV, VIS and NIR respectively [see details below]. Acousto-optic tuneable filters for the visible and infrared channels and Fabry-Perot interferometer for the ultraviolet channel. For some of the trace gases only solar or lunar occultations are used.
Background

New development
Scanning Technique

Limb sounding by bright limb, solar, lunar and star occultation. 25-40 stars/orbit, i.e. average 500 occultations/day, global. Few tens/day for solar occultation, limited to latitudes above ~70°.
Resolution 1 km vertical, 300 km horizontal (limb geometry)
Coverage / Cycle The orbit has a 3 day repeat. The spatial coverage is limited with a global coverage/day of one measurement every 1000 x 1000 km2 cell on average.
Mass Power 250 W Data Rate

 

Providing Agency ESA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2025 to 2028
Last update: 2024-07-01
Detailed characteristics

Spectral Range

Spectral resolution

SNR @ expected input radiance

250-355 nm

 2.5 nm

 >70

440-675 nm

10 nm

>200

600-1020 nm

10 nm

>200
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 occultation limb sounder
  • Subcomponent 2
  • UV/VIS/NIR/IR/MW limb sounders
  • UV/VIS/NIR/IR occultation limb sounder
Mission objectives
Primary mission objectives
  • Aerosol Layer Height
  • Aerosol Optical Depth
  • Aerosol mass mixing ratio
  • Atmospheric temperature
  • H2O
  • NO2
  • O3
  • PSC occurrence
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
Aerosol mass mixing ratio*5 - marginalLimited to high atmosphere.UV, VIS, NIR limb sounding by solar & stellar occultation. Self-calibrating
BrO5 - marginalLimited to high atmosphere.. Daylight only.UV spectrometry. BrO lines around 300 nm. Limb sounding by solar occultation.
O3*5 - marginalLimited to high atmosphere.Ozone lines in the bands around 260 nm (Hartley) and/or 340 nm (Huggins) and 600 nm (Chappuis).
PSC occurrence*4 - fairLimited to high atmosphere.UV and VIS spectrometry.
Aerosol volcanic ash5 - marginalLimited to high atmosphere.UV, VIS and NIR spectrometry; limb sounding by solar & stellar occultation. Self-calibrating
Atmospheric temperature*5 - marginalLimited to high atmosphere.. Daylight only.VIS spectroscopy at lower resolution 10 nm
Specific humidity5 - marginalLimited to high atmosphere.. Daylight only.NIR spectrometry with several water vapour bands (main: around 940 nm).