1. GRWG VIS/NIR sub-group briefing report
GSICS VIS/NIR Sub-Group Members presented by David Doelling
GSICS annual meeting, Shanghai, China, March 19-23, 2018

2. Wish to thank CMA for hosting GSICS meeting
Many CMS VIS/NIR presentation in the mini conference and during the lunar and VIS/NIR sessions
Hope to gain new calibration insights

3. GSICS and CEOS IVOS recommended solar spectra
Short term approach to construct a solar spectra based on the best solar spectra datasets, which have been scaled to a common TSI reference in the more temporal stable part of the spectra. (Thuillier and COSI datasets)
Long term approach to account for the variability in the UV radiation, the solar sunspot cycle, and higher spectral resolution using both observed and modeled datasets
No solar spectra meetings anticipated this year

4. VIS/NIR Reference Instrument
Status of Terra/Aqua MODIS and NPP/JPSS1 VIIRS to be presented by Jack Xiong in VIS/NIR section Thursday afternoon.
Propose to use NOAA IDPS VIIRS dataset with correction factors referenced to the NASA LandPEATE version 1 calibration
There are multiple calibrated versions of VIIRS
Propose using the I1 band for the 0.65µm, since the spectral response is very similar to the new GEOs
Topic to be discussed in the VIS/NIR section on Thursday afternoon

5. Transfer of the reference calibration
We are in the process of migrating to NPP-VIIRS as the reference instrument
Most of the new 3rd generation GEOs will have similar band spectral response functions as VIIRS.
There will be four more VIIRS instruments on JPSS-1 through JPSS-4
Aqua-MODIS is ageing and will be de-orbited by 2023
Would like to see a transfer of the MODIS and VIIRS band calibration using the moon
The GSFC and Langley NASA teams are working on Aqua-MODIS and NPP- VIIRS scaling factors as well as future NPP-VIIRS and JPSS-1 scaling factors
Doelling presentation in VIS/NIR session on Thursdays afternoon

6. Spectral Band Adjustment Factor Status
There are 3 VIS/NIR hyperspectral datasets that can be used for SBAF
SCIAMACHY 30x240 km FOV, mostly complete visible spectra (except > 1.6µm), high resolution spectra
GOME-2 40x80 km FOV, limited visible spectra, high resolution spectra
Hyperion 30m FOV, complete spectral range, low spectral resolution, limited sampling
NASA-Langley SBAF tool (web site here)
The Hyperion and GOME-2 now have the same functionality of SCIAMACHY
AIR and IASI are now updated
The SCIAMACHY, Hyperion, and GOME-2 spectral plotting tool is functional
Additional SRF and solar constant tools
Ben Scarino presentation in VIS/NIR session on Thursday afternoon

7. Lunar Calibration Status Sebastien and Tom
2nd Lunar Calibration Workshop held in Xi'an China in November
Development of the GIRO benchmark for validating lunar models
Using the Moon to character the sensor MTF effort is being lead by NOAA
GIRO/GLOD license agreement have been recently signed by JMA, USGS, KMA, JAXA, CNES, ESA
The distribution of the GIRO code has started for those agencies. But the GLOD will be provided at a later stage once it is consolidated

8. GIRO benchmark status
Primary purpose is to validate the GIRO model against OLRO reference
Complete benchmark dataset created by EUMETSAT (Seb Wagner)
Designed to work with GIRO
Results delivered to USGS for comparison to ROLO
Initial comparison test have been run, preliminary results will be shown at talk 7f Thursday

9. DCC Calibration Status
Most GPRCs have implemented the DCC calibration successfully
KMA to discuss their implementation in VIS/NIR discussion section Thursday afternoon
Obtain demonstration product status this year
Need product acceptance procedure
Write a GSICS DCC calibration methodology/implementation paper that combines the efforts of all GPRCs
Begin to implement DCC methodology for GEO SWIR bands
DCC product file convention is nearly finalized
Bias plotting package is being developed

10. Combining VIS/NIR method calibration gains
Combine the multiple calibration approaches to provide users calibration coefficients with the least uncertainty for their application
GSICS to provide to both lunar and DCC calibration coefficients, as well as an optimized blend
Some methods are suited for stability or calibration transfer, the uncertainties will vary by wavelength
Some methods are best suited for certain retrievals,
ocean color/aerosols would rely more on Rayleigh scattering

11. New VIS/NIR approaches
Advance the Rayleigh scattering approach
Yusuke Yogo to present the JMA Rayleigh scattering approach during VIS/NIR section
Bertrand Fougnie to present and begin formulating Rayleigh scattering approach during VIS/NIR section
GPRC VIS/NIR priorities
During the VIS/NIR section we hope to obtain the GPRC priorities in order to prioritize and combine VIS/NIR efforts

12. Rethinking L1B calibrated radiance datasets
Currently, every time the L1B imager data is reprocessed, which can be yearly, you have to download the whole dataset (TB’s) all over again
If the user could only download the dataset once and apply calibration modules, could save reprocessing and storage requirements
Must ensure accurate calibrated radiances when applying calibration module
The remote sensing instrument community would release a level 1b dataset that contains all of the required on orbit instrument measurements.
The calibration module can then be downloaded and applied to update calibration, for example the Terra-MODIS WV detector striping anomaly
The instrument providers would then provide a calibration module and test dataset to ensure proper implementation, similar to GOME-2 and SCIAMACHY
I have presented this at the 2017 CALCON and November CLARREO meeting
Two reservations, the users do not want to apply a post calibration (if only grabbing small amounts of the data
The onboard calibration parameters are too extensive and perhaps the instrument calibration team loss of control of the dataset
When reviewing papers that use dataset, make sure the authors attribute the project name, product name, version number and doi.

13. Rethinking L1B calibrated radiance datasets

14. VIS/NIR discussion topics
Recommended VIIRS channels as calibration references
Which L1B calibrated product?
Discuss the impact of multiple existing VIIRS calibrations
Is there a better way?
GSICS multi-GPRC DCC calibration paper
Begin to implement DCC methodology for GEO SWIR bands
GSICS requirements for CLARREO Pathfinder mission
Rayleigh scattering calibration approach next steps
Web meeting agenda
GPRC VIS/NIR upcoming priorities
Rethinking L1B calibrated radiance datasets