1. Summary 2017 GRWG+GDWG meeting Tim Hewison
Special Issue of the IEEE TGRS on “Inter-Calibration of Satellite Instruments”:
Special Issue of the IEEE TGRS on “Inter-Calibration of Satellite Instruments”:
01 January 2019
Summary 2017 GRWG+GDWG meeting Tim Hewison

2. Executive Summary
Good – some steady progress, but limited by being under resourced – lots of ideas, but not enough resources to follow-through:
Given the current concerns about CLARREO funding, the CLARREO team are looking for white paper stating the importance of the traceable reference instrument on-orbit.
LEO-LEO inter-calibration should be developed for LEO imagers to complement the current GEO-LEO products.
Many topics concluded that inter-band calibration is important and should be given a higher profile in GSICS.
Progress in two key GDWG activities; synchronisation of GSICS products across calibration servers and the creation of GitHub repositories for collaboration developments.
Updates to the GSICS ToR have been prospered to clarify the roles of the co-chairs, and to clarify the resources needed to support GDWG systems development and operations of these system as requested by the 2016 CGMS action A44.04

3. IR Sub-Group session
GEO-LEO IR products – which are now available (at different levels of maturity) for all current GEO imagers. This allows them to be inter-compared as part of the GEO-ring initiative.
The diurnal calibration variation is also now becoming more and more important as most of the platforms are now 3-axis stabilised. Techniques are being developed to characterise the diurnal variations using multiple reference instruments and GEO-GEO comparisons.
Developing a report on the traceability and uncertainty of the current GSICS IR reference instruments, building on Dave Tobin’s analysis of the CrIS calibration error budget, and a series of comparisons between different reference instruments based on different techniques. However, progress is slow – not only on our side.
Starting to develop GSICS deliverables for the LEO-LEO IR and scoping the potential for defining spectral corrections or retrieving SRFs. There was particular interest from SSEC in the application to HIRS, based on comparisons with IASI on Metop. However, we were unable to commit to follow this up. One outstanding activity critical to SLSTR (amongst others) is to characterise the uncertainty introduced by extrapolating IASI’s radiance spectra to shorter wavelengths.
Instrument specification, pre-launch char, cal/val testing: a workshop is being planned (date to be confirmed)

4. GSICS GEO-LEO IR Product Status 2017-03
01/01/2019
GSICS GEO-LEO IR Product Status
GPRC
Monitored Instrument
Reference Instrument
GSICS NRT Correction
GSICS Re-Analysis Correction
GSICS Bias Monitoring
EUMETSAT
Meteosat-8-11/SEVIRI
Meteosat-7/MVIRI
Metop-A/IASI
Operational
Demo
Plots RAC
JMA
MTSAT-2 Imager
IASI (+ AIRS)
NOAA
GOES-13 & -15 Imager
GOES-11 & -12 Imager
Pre-op
Prototype
GOES Sounder
Development
In development
CMA
FY2C – E
KMA
COMS-1
IASI
Submitted as Demo
ISRO
INSAT-3D
Full GSICS Product Catalog available at

5. Linking the GEO ring Comparing GEO-LEO and GEO-GEO Differences
To Validate Uncertainty estimates
Ensure consistency
Generate global L2 products
SCOPE-CM IOGEO

6. Lunar Calibration session
The achievement of GIRO/GLOD licensing, which was greatly appreciated.
Developing inter-calibration method and products
Defining detailed plans for the next Lunar Calibration Workshop, which will take place in China in autumn Final date and location will be decided by end April 2017.
We received a request from CMA for GOME-2 lunar data and from Dave Doelling and CMA for GOME-2 degradation model.

7. VIS/NIR session
Further development of the DCC method to improve the characterisation of the seasonal variations and a publishing a paper or special issue on the subject.
The decision to move now from Aqua/MODIS to S-NPP/VIIRS as our inter-calibration reference.
Debrief on IVOS discussion on Reference Solar Spectrum
Vicarious calibration monitoring of Sentinel-3/OLCI and SLSTR
Combining inter-calibration methods – which led to a long discussion and is clearly the subject for further work.

8. UV session
There is growing interest in the UV Sub-group activities ~approx. 20 participants (see minutes for list of participants). Four projects were presented - Reference Solar Spectrum; Match-ups and Targets; Cross-calibration below 300nm (ozone profile project); White Paper on On-ground Calibration and Characterisation.
There is most interest in the Reference Solar spectrum project - L. Flynn NOAA will continue to collect more spectra from participants and expand the analysis. The aim is to make a recommendation for a high spectral resolution reference solar spectrum to be accepted by the community as a standard. This selection will also be communicated to the VIS/NIR sub-group who have less need for high spectral resolution.
The White Paper on On-ground Calibration and Characterisation is also of interest to the broader GSICS community, and relate to the workshop on this topic planned jointly with CEOS WGCV. Drafts based on UV/VIS spectrometers will be circulated to a wider group when available.
In general there is a need to develop tools etc for community use to generalise the methods available in individual Agencies (mainly NOAA) for use by other participants. Here we are lacking resource. The first action (Rose) is to define what would be needed so we can then explore possibilities for tools development, potentially through an external study or activity.

9. Microwave Sub-Group session
Microwave sub-group, chaired by Ralph Ferraro (NOAA, remotely!), also met, covering a range of topics including
updates on the problematic ATMS calibration,
reviewing potential GSICS products for the window and temperature-sounding channels
Discussion of new blackbody standards and
choice of on-orbit reference instruments – including the potential use of FCDRs as a reference.
RTM issues were also discussed.

10. GDWG Breakout Session
Overall a successful meeting where 15 agenda items were discussed resulting in 29 new Data Management related actions.
KMA have assigned a new GDWG member, Jin Woo, who contributed significantly to the GDWG.
 Updates to the ToR proposed are to clarify the term of service for the co-chairs of the GDWG as it currently only provides a reference for the Chair; 3 years renewal, with the vice chair taking on the chair role after this term if needed.
 This clarification is needed as if the 3 year renewal term is applied to the co-chairs, they would have completed their term of service at the end of If this is the case, the GDWG is required to make a recommendation for chairing the group from This has been discussed by the group and a controversial proposal has been made which needs support from the EP to clarify how the GDWG should conduct the recommendation of chairs in the future.

11. External Partnerships
GRUAN
Tony Reale presented some work on the use of the GCOS reference upper air network radiosondes for satellite calibration validation.
He was encouraged to submit a draft uncertainty analysis to show how this could be applied to IR and MW instruments, due to concerns about the limiting effects of atmospheric variability and the small number of collocations with radiosondes.
ISCPP
Ken Knapp (NOAA) taken over stewardship of ISCCP (International Satellite Cloud Climatology Project)
Discussed ways to assess impact of GSICS corrections on ISCCP products
Requested 1 month of test data for VIS & IR GEO imagers from Dec 2009
Important & high profile feedback for GSICS

12. Thank You for your contributions!