GSICS webmeeting on the Annual Calibration Report
Chair: Fangfang Yu
Minutes: Tim Hewison
CNES: Laura Le Barbier
CMA: Scott Hu, Na Xu, Chengli Qi, Ning Lei
ESA: Paolo Castracene, Stefano Casadio
EUMETSAT: Tim Hewison, Dorothee Coppens, Sebastien Wagner, Ken Holmlund, Rose Munro
IMD: Ashim Mitra
JMA: Arata Okuyama, Kuzuki Kodera, Tanaka Hidecki
KMA: Dohyeong Kim, Minju Gu, Eunkyn Kim, Tae-Hyeong Oh
NOAA: Fangfang Yu, Larry Flynn, Robbie Iacovazzi, Manik Bali, Flavio Iturbide, Mitch Goldberg, Fred Wu
NASA: Amit Angal, Sirish, Taejoung Choi, Jack Xiong, Dave Doelling, Aisheng Wu, Ben Scarino, Vincent Chiang
UMBC: Larrabee Strow
UMD: Hyelim Yoo
WMO: Werner Balogh, Heikki Pohjola
Fangfang introduced the web meeting and presented the proposed outline of the GSICS Annual Calibration Reports, including lists of revelant events, summary tables of bias and variability in all channels of each monitored instrument - usually over the last year - and long-term trends, including plots where necessary. In discussion, it was emphasised that at least the primary reference instrument for each band should be used - this is currently IASI-B for the IR. (Decision?)
She also highlighted the outstanding need for characterisation of other components of the radiometric uncertainties - particularly radiometric noise and geometric calibration accuracy.
A.GWG.20200416.1: Dorothee Coppens (EUMETSAT) to circulate plans for Metop-A End Of Life testing, which is expected for 2021Q3/Q4 for IASI
CMA's report covered both their GEO instruments:
FY-4/AGRI: Shengli showed strong attentuation of the reflected solar bands' calibration coefficients, especially at the shortest wavelength - and that the striping issue previously experienced in AGRI has been alieviated by the introduction of an adaptive wavelet filter.
FY-4/GIIRS has also been improved substantially during 2020 - in terms of spectral, radiometric and processing optimizations, which have resulted in fewer bad granules
CMA plan to generate GSICS corrections for AGRI and add GIIRS inter-comparisons to their GSICS portfolio in 2020, which was strongly encouraged.
CMA were also encouraged to quantify the variability of the biases in their future Annual Calibration Reports.
EUMETSAT covered the performance of all 4 SEVIRI imagers, which are currently operational on all Meteosat Second Generation satellites. Their calibration is now basically stable, so Tim's presentation focused more on the details of what should be included in the report. He proposed that if GSICS agencies generate GSICS Corrections for their instruments and upload them to the Data and Products Servers, it would be possible to develop common scripts to generate the contents of the Annual Calibration Report. This could be followed up in the Data Working Group.
Recommendation: - TBC?
A.GDWG.20200416.1: Manik Bali (NOAA) to coordinate GDWG to investigate developing scripts to generate contents of Annual Calibration Reports from GSICS Corrections.
Tim went on to summarise comparisons between IASI-A and IASI-B based on time series of the double-differences, highlighting the small, but measureable impact of the updates to their onboard processing. He showed that since September 2019 their calibration is now very well aligned - within 25mK for standard radiance scenes.
Ashim showed comparisons of INSAT-3D and -3DR with AVHRR and results of comparisons with in-situ measurements in the Raan of Kutch.
IMD were encouraged to implement GSICS algorithms to monitor the calibration of their satellite instruments.
Arata summarised the mean calibration bias and uncertainty in all the channels of the AHI imagers on Himawari-8 and -9, based on GSICS GEO-LEO algorithm for the IR channels as well as Ray-matching and vicarious calibration for the Reflected Solar Band.
He explained that the Himawari-8/AHI VNIR channels' calibration coefficients were updated in July 2019 as annual event. He also showed that revising the Best Detector Selection map, which reduced the striping. The selection map was updated in 2019 for the first time in 2 years.
There were interesting discussions on features of the results, including the apparently anomalous degradation of the 0.47µm channel.
Tae-Hyeong presented the result of KMA's calibration monitoring applied to the COMS and new AMI imagers' reflected solar band channels, which will be further extended in next week's web meeting. Minju showed the results from the GSICS GEO-LEO IR algorithm. These were applied during the AMI commissioning to identify a small shift in the 13.3µm channel's Spectral Response Function, which have alread been communicated to the user communities.
Fangfang Yu - NOAA GEO Annual Calibration Report - need to link to presentation
Fangfang summarised the calibration of the ABI imager on GOES-16 and -17. She explained the CAL LUTs had been updated in April 2019, and that the newly implemented Predictive Calibration Algorithm improves the calibration of the GOES-17 IR channels during nighttime (which is expected to continue to improve). All calibration of all IR channels on GOES-16/ABI is now excellent (within 0.1K), but there are residual biases in the sounding channels on GOES-17, which are thought to be due to SRF changes due to operating at non-nominal temperatures and are expected to be reduced in future.
NASA's analysis of SNPP/VIIRS confirmed the continued good performance, with noise much better than requirements and improved modelling of the solar diffuser screen transmittance, which has improved the calibration stability. NASA showed all channels are now very similar to NOAA's F-factors for NOAA-20/VIIRS. They plan to use lunar observations to further adjust the degradation model.
Jason reported that all VIIRS bands' calibration have been stable since the LUT update in April 2018 - so NOAA have adopted constant F-factors. They have also consolidate solar diffusor and lunar F-factors within 1%.
It was pointed out that only absolute Moon phases between 2° and 92° are supported by GIRO.
Flavio Iturbide - NOAA CrIS Calibration Report
Flavio reported the SNPP CrIS
anomaly in 2019. After the electronic side switch, the radiometric and geometric calibration accuracies and the noise performances are comparable with those before the switch.
- GPRC GEO Instrument report (10 minutes for each agency)
- GSICS reference instrument report (L1B
products) (10-15 minutes for each L1B
Calibration and Data Collection (NASA VIIRS Land SIPS L1B
VIIRS (NOAA VIIRS VNIR SDR)
Discussion/Wrap-up (20 minutes)