GRWG/GDWG IR Group Web Meeting 2021-07-08


1) Xingwei He (CMA): Assessing Radiometric Calibration of FY-4A/AGRI Thermal Infrared Channels Using CrIS and IASI

2) Flavio Iturbide (NOAA): Update on CrIS /SNPP status (No slides available please contact him directly at


Guest Chair: Likun Wang (NOAA Affiliate)

ESA: Paolo Castracane

JMA: Kazuki Kodera, Arata Okuyama, Misaki Eiki, Kazutaka Yamada

KMA: Minju Gu

CMA: Xingwei He, Chengli Qi, ZhangQrl (?)

NOAA: Likun Wang, Fred (Xiangqian Wu) Wu, Fangfang Yu, Erin Lynch, Peter Beierle, Manik Bali

Universität Hamburg: Martin Jörg Burgdorf


1) Xingwei He (CMA): Assessing Radiometric Calibration of FY-4A/AGRI Thermal Infrared Channels Using CrIS and IASI

Xingwei presented the inter-calibration results of using SNPP/CrIS and Metop-B IASI to assess radiometric calibration of FY-4A/AGRI thermal infrared channels. The results include six IR bands except for SW IR channel 8 with central wavelength 3.8µm that are not full covered by the IASI and CrIS. For the CrIS, the CrIS gap filling methods are used to fill the spectral gaps. The overall statistics, scene dependent feature, diurnal variation, long-term time series, and spatial distribution of GEO-LEO brightness temperature (BTs) bias were presented.
Likun Wang (Comments): Hui Xu from UMD has developed the coefficients to extend IASI spectra toward SW spectral domain. You can contact him if you like use IASI to inter-calibrate channel 8 (3.8µm).

Fred Wu (Question): For diurnal variation slides, this is one day’s results or the results based on several days (how many days) average?
A: It is based on Four Months’ data.

Fred Wu (Question): Why are the mid night are so different in the slide 6?
A: Mid night is the local time.

Likun Wang (Question): For slide 7 on long-term time series of BT bias, there are sudden changes indicated by the red arrows. Do you have any ideas what calibration parameters were updated for these sudden changes?
A: This was done by another group, and I will contact them to understand.

Fred Wu (Question): How many are there focal planes for FY-4A/AGRI IR channels?
A (Chengli Qi): I will find the information to send you the email.

Fangfang Yu(Question): For slide 8 on spatial distribution, they are daytime or nighttime data?
A: They are both and mixed together.

Likun Wang (Question): In your summary slide, you showed that Channel 10\11\14 show gradual degradation. What does it mean? What physical reason caused that?
A: I mean the trend of the bias.

Arata Okuyama (Question): For seasonal variation slides, do you think sensor have calibration diurnal variation effects or this is artificial effects? I also have similar features sometimes.
A: I don’t know the answers.
(Comments from Likun Wang): This is really a good question. It is really hard to distinguish these two.

Fred Wu (Comments): Slide 7, channels 10 and 11 have downward trends. It is somehow I was thinking there are on the different focal planes. This downward trend is different from channel 13’s upward trend. These features should not be caused by the blackbody.

Likun Wang(Comments): Following Fred Wu’s comments, if you use the results on Slide 7 to bin the data together to investigate the diurnal variation. The trend and seasonal variation will be mixed together.

2) Flavio Iturbide (NOAA): Update on CrIS /SNPP status (No slides are available and please contact him directly at

Flavio gave the oral updates on CrIS /SNPP status. He said that it is scheduled for CrIS /SNPP to switch to Side 1 for LW coverage (needed for NWP) on July 12. After Side 1 switch, there will be calibration and validation efforts to adjust all calibration parameters.

Likun Wang (Question): Are there any data format changes after switch?
A: It is not what we expect.

Fangfang Yu (Comments): Are there any plan to switch the GSICS reference from SNPP/CrIS to NOAA-20/CrIS?
A (from Likun Wang and Manik Bali): Manik will find the procedures from IASI-A to IASI-B switch based on previous switch.

Arata Okuyama (Question): How long will it take for CrIS Cal/Val work?
A: We expect it will take 3-4 weeks.

Likun Wang (comments): I suggest that the GSICS community should prepare for the switch from SNPP/CrIS to NOAA-20/CrIS.

Finally, Likun Wang shares the special issue information on special Issue "Satellite Observations on Earth’s Atmosphere" from Remote Sensing (You find the information here). Flavio also mentioned there JSTAR Special Issue announcement for future GEO and LEO sounders.


R.GIR.20210708.1: It is recommended that the GSICS community should prepare the switch from SNPP/CrIS to NOAA-20/CrIS as the GSICS Reference.
Topic revision: r3 - 20 Jul 2021, LikunWang
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding GSICS Wiki? Send feedback