GSICS References GSICS in-orbit References are in-orbit instruments that are highly stable instruments, that can help in monitoring other in-orbit instruments when compared with. Below is a table with references for each channel.

Channel Reference Instrument/Record Period *Version* Status Major Events GSICS Maturity End Date Recommendation to Users
Infrared IASI-A Deorbiting
End of Life Schedule
Apr 2021 Switch to IASI-B/C/ and Beyond for instrument monitoring
IASI-B Operational
IASI-C Operational
NOAA-SNPP/CrIS Instrument completes designed lifespan Change of Electronics July 22, 2021 Switch to Jx-CrIS for instrument monitoring
NOAA-20/CrIS Operational
AIRS Operational
MODIS(AQUA) 2002 to 2018.
NOAA-20/ATMS SDR Version
Glossary * Channel * Reference Instrument * Period ( of best reference) * Version: The version of records that is best recommended ( can be more than one ) * Status: Most recent status of the reference instrument that can directly impact inter-calibration outcomes. * Major Event: Major events during the best lifetime of the reference instrument * GSICS Maturity: Three colors denoting ( Green: If GSICS has formally designated it as GSICS Reference, Yellow: If recommended as a GSCICS reference ).
Reference Selection Matrix

IR sounder
1. Sensor performance stability
2. Spectral coverage/Spectral resolution
3. Error budgets (prelaunch characterization and post-launch verification)
4. Geo-location accuracy
5. Data availability

MW sounder

1. Sensor performance stability
2. Field of view (FOV) consistency (ATMS has oversampling FOV and can be B-G to AMSU-A and MSU)
3. Error budgets (prelaunch characterization and postlaunch verification)
4. Geolocation accuracy
5. Data availability


•The reference instrument must have an active instrument calibration team funded by the project over the lifetime of the satellite

  • Must have onboard calibration that is well characterized, preferably with SD and lunar monitoring
  • The pre-launch and on orbit calibration must be well documented in journals
  • The data must be publicly available and easy to order and download and be released in near real-time
  • The instrument must have many users to verify the calibration and discover any calibration anomalies

For the UV we don't have a reference instrument and a selection Matrix


as yet, however GOME and OMPS are the most commonly used instruments for 200nm-350nm measurements

** References*

Likun Wang NOAA IR Reference Sensor Traceability and Uncertainty 3q

Manik Bali et a. NOAA Selecting GSICS References: IR, VIS and MW 3e
Related Decisions

D.GIR.2019.7k.1 All agencies to switch to IASI-B asap as Anchor reference for NRTC and RAC products.
D.GIR.2018.4w.1 CrIS accepted as a reference on the basis of a positive answer to all the above questions.
D.GVNIR.2017.8u.1 S-NPP/VIIRS a GSICS inter-calibration reference.
Topic revision: r8 - 23 Mar 2022, ManikBali
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