GRWG VIS/NIR + IVOS Web Meeting on

Planning 2017 Lunar Calibration Workshop

GSICS Web Meeting on 2016-12-06

Agenda

1. NOAA (F. Yu): latest results on the NOAA developments regarding lunar calibration: Lunar Radiance Site Selection
2. NOAA (T. Choi): update on the NOAA VIIRS lunar calibration
3. Zedikasolv (G. Matthews): Moon observations and Earth Radiation Budget instruments
4. Discussion: Second Lunar Calibration Workshop in 2017 - Workshop topics
   1. Measurements and Moon observations
   2. Using the ROLO/GIRO
   3. Inter-calibration using the Moon
   4. Alternative methods and applications

Attendees

Guest Chair: Sebastien Wagner - EUMETSAT

AIST: Toru Kouyama

CMA: Scott Hu, Lin Chen, Yang Wang, Rongua Wu

CNES: Bertrand Fougnie

Earth Space Solutions: Matthijs Krijger, Ralph Snel

EUMETSAT: Sebastien Wagner, Tim Hewison, Bartolomeo Viticchie

IMD: --

ISRO: --

JAXA: Hiroshi Murakami (EORC)

JMA: Masaya Takahashi, Arata Okuyama

KMA: Hyesook Lee, Tae-Hyeong Oh, Eun-Kyu Kim

NASA: Truman Wilson (NASA/GSFC), Zhipeng Wang (NASA/GSFC), Lawrence Ong (NASA/GSFC), Brian Markham (NASA/GSFC)

NIST: Stephen Maxwell

NOAA: Xiangqian Wu, Fangfang Yu, Manik Bali, Jason Choi

ROSHYDROMET: --

USGS: Tom Stone

VITO: Stefan Adriaensen

WMO: --

Zedikasolv: Grant Matthews

Summary

The meeting started with a few presentations left from the previous web meeting - although Ashim Kumar Mitra (IMD) is unavailable today.

1. NOAA (F. Yu): latest results on the NOAA developments regarding lunar calibration: Lunar Radiance Site Selection

Fangfang Yu gave a summary of her progress to characterise selected lunar sites as radiance references (as opposed to irradiance, as used by ROLO), which was presented at CALCON 2016.
She explained the most challenging aspect is the image-to-image registration, so the first step is to collocate different instruments on the same target. She also showed examples of the trade off between site size and noise, identifying large uniform sites at low elevation, suitable for GEO and LEO instrument-instrument inter-calibration and band-band degradation trending.

Question: Do NOAA intend to develop a BRDF model using AHI?

Answer: Yes - but also including other satellite data (such as SELENE, ABI and PLEIADES) to give a better geometric coverage.
NOAA expect to provide an update on the collocations in time for the March 2017 GSICS WG meeting.

2. NOAA (T. Choi): update on the NOAA VIIRS lunar calibration

Jason described his analysis of the VIIRS lunar observations to validate the calibration derived from the onboard solar diffuser (and its monitor). There was discussion about the approach adopted to avoid defining oversampling factors.

After a question by Lawrence Ong (NASA), Jason explained that the band M11 was chosen as a reference band for the analysis as it is the most stable in time. It is used as a reference band to check the evolution in time of the Solar Diffuser and Lunar Band Ratio.

3. Zedikasolv (G. Matthews): Moon observations and Earth Radiation Budget instruments

Grant Matthews described the application of lunar calibration to the Earth Radiation Budget experiments - ultimately to improve the ability to resolve the significance of climate trends. His previous work was based on the ratio of one Sun and Moon observation per day, which was noise limited to ~2%. Similarly, he derived the mean lunar surface temperature from a broadband long-wave channel.

Question: Grant was asked how to account for SW channel’s sensitivity beyond 2.5µm.
Answer: generates spectrum, based on assumed lunar surface temperature gradients and derived thermal emissivity. Improvements would require spectral characterisation of the lunar irradiance in the SWIR to the limit of the ERBE SW detectors (5µm). This could be discussed further at the 2017 Workshop.

4. Discussion: Second Lunar Calibration Workshop in 2017 - Workshop topics

Sebastien provided an update on the status of the GIRO and GLOD licence agreement. The licence agreement is ready and the official document to sign is about to be circulated for signature.
The cases to be used for the benchmarking dataset have been agreed, but the preparation of cases has not yet started. This benchmark will allow, among others, the validation of future versions of the GIRO vs ROLO.
He also gave an update on the study using SCIAMACHY data to validate the Spectral Band Adjustment Factors derived from GIRO, which are needed to generate inter-calibration products.

Sebastien also provided an update on plans for the Lunar Calibration Workshop. Scott confirmed that CMA propose to host the workshop at Dunhuang in the Gobi desert, during September 2017. Potential participants are encouraged to check their availability and travel arrangements to reach this site for dates in September 2017.

Topics for the lunar calibration workshop (discussion):

a) Measurements and Moon observations (proposed chair: Scott Hu - CMA):

See list of actions.

Agreed to include a presentation on GLOD database.

b) Using the ROLO/GIRO (proposed chair: Tom Stone - USGS):

• Use of the benchmarking dataset to characterise the new spectral analysis and interpolation
• New solar spectrum to accommodate hyperspectral instruments
• Uncertainties in lunar irradiance measurements (including oversampling factor), polarisation sensitivity, evaluation of deep space signal and Moon extraction methods.
• Potential improvements of spectral interpolation method used in the ROLO/GIRO, based on newly analysed datasets (e.g. SCIAMACHY)
• Other future improvements in ROLO (on the shape of a brain storming)

c) Inter-calibration using the Moon (proposed chair: Sebastien Wagner - EUMETSAT)

• Inter-calibration (following the progress made by EUMETSAT and JMA)
• Cross-calibration
• Inter-band calibration

d) Other possible topics (proposed chair: Fred Wu - NOAA):

• Radiance models
• Thermal IR & Microwave models of the Moon
• Band-band co-registration
• MTF characterisation
• Characterisation of cross-talk

Outcome

Action GRWG.20161206.1: Jason Choi (NOAA) to coordinate with NASA (Zhipeng Wang) to compare the VIIRS lunar results analysed by both teams.

Action GRWG.20161206.2: Sebastien Wagner (EUMETSAT) to set up a Doodle poll to establish whether the proposed location would introduce any difficulties to attendees.

Action GRWG.20161206.3: Scott Hu (CMA) to invite NIST and NASA ARCSTONE to present their activities.

Action GRWG.20161206.4: Fred Wu (NOAA) to consider coordinating a summary of new space-based Moon observations (since the last workshop).

Action GRWG.20161206.5: Scott Hu (CMA) to invite national metrology agencies to describe characterisation of instrumentation and its traceability to SI-standards (certification).

Action GRWG.20161206.6: Sebastien Wagner (EUMETSAT) to contact Jack Xiong (NASA) to discuss about the characterisation of cross-talk using lunar observations.

Action GRWG.20161206.7: Sebastien Wagner (EUMETSAT) to set up a Doodle poll to allow potential participants to indicate their interest in different topics.

Action GRWG.20161206.8: session chairs (Scott Hu, Tom Stone, Sebastien Wagner, Fred Wu) to coordinate speakers for each topic.