IR group web meeting on Dec 4, 2025
Agenda
1) Xingwei He (CMA) : Correction of Crosstalk Within Channel 7 of Geostationary High-speed Imager (GHI) onboard the Fengyun-4B satellite. (20 minutes + 10 minutes discussion)
2) Yuqing He (Beijing Institute of Technology): Uncertainty Evaluation of AGRI-IASI Cross Calibration in Infrared Channels. (10 minutes + 10 minutes discussion)
Attendees
Guest Chair: Chengli Qi
CMA: Chengli QI, Xingwei He, YunKai Xu, Yifan Jin,
BIT: Yunkai Xu, Yuqing He
UMD: Likun Wang
NOAA: Fangfang Yu, Xiangqian Wu
EUMETSAT: Tim Hewison, Mounir Lekouara, Vincent Debaecker
JMA: Shin Koyamatsu, Tsuguyoshi Toma
UW: Joe Taylor, David Tobin
ESA: Paolo Castracane
Prathana:?
Summary
1) Xingwei He (CMA) : Correction of Crosstalk Within Channel 7 of Geostationary High-speed Imager (GHI) onboard the Fengyun-4B satellite. (20 minutes + 10 minutes discussion)
Xingwei He first presented the crosstalk issues from the GHI images: discontinuity BT at adjacent line stitching positions. The ground experiment of using backup GHI unit further confirmed this issue. She then presented the crosstalk correction model. The model works well with and without correction in slides 14-15 based on quantitative evaluation. Finally, she shows one example on Typhoon images before and after correction: the images get smoother. The inter-calibration results of GHI-IASI before and after correction are also presented (Slide 21).
Mounir Lekouara: 1) electronic detector or optical gray light? 2) updated frequency. 3) suggesting using EUMETSAT method.
Q: 1) I am not sure of the answer, 2) daily
Fred Wu and Fangfang Yu: Channel 6 in ABI has small and weak crosstalk issues. It is hard to see and thus we don’t correct it.
Fred Wu: IASI-GHI inter-calibration scatter plot on slide 20: what are X and Y axis
A: X is IASI and Y is GHI. Inter-calibration at Cold BT regiones is improved.
2) Yuqing He (Beijing Institute of Technology): Uncertainty Evaluation of AGRI-IASI Cross Calibration in Infrared Channels. (10 minutes + 10 minutes discussion)
Yuqing He first presented background and related studies in previous studies (Hewison et al. 2013). The factors affecting uncertainty were discussed. They are separated into systematic and random errors. The results are presented from slides 20-25.
Tim Hewison: 1) Are there any recommendations to improve uncertainty analysis? 2) suggestions: uncertainty related to standard scenes and different scenes. How can they be related to inter-calibration accuracy?
A: Recommendations: a) This method can be used to other inter-calibration pairs? b) Geometry uncertainties can be applied to LOS vectors.
Question 2: use different threshold values for different scenes.
Dave Tobin: What is the coverage factor for these total uncertainties? Confidence level? K=1, 2 …
Question: K=1, one sigma.
ChengLi Qi: any results on IASI-MERSI?
A: LEO-LEO results are similar even the samples are quite different.