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

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

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

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

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

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

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

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

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

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

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

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.

Rethinking L1B calibrated radiance datasets

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