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
	NOAA-21/CrIS
	AIRS			Operational
	MODIS(AQUA)			2002 to 2018.
VIS/NIR	NOAA-20/VIIRS		SDR Versions
	NOAA-21/VIIRS
Microwave	AMSU/MSU FCDR
	NOAA-20/ATMS		SDR Version
UV

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

VIS/NIR

•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.