GRWG/GDWG Web Meeting 2022-07-21
GSICS IR Sub-Group Web Meeting
- Munn Shukla (ISRO) : Inter-calibration of INSAT-3DR
- Samuel Quesada Ruiz (ECMWF): GEO imager's IR channel bias monitoring at ECMWF
Guest Chair: Likun Wang (UMD)
EUMETSAT: Ali Mousivand, Tim Hewison, Mounir Lekoura, Viju John
ISRO: Munn Shukla, Munn Vinayak, Pradeep Thapliyal
JMA: Misaki Eiki, Kazuki Kodera
KMA: Hyelim Yoo
NOAA: Likun Wang, Manik Bali, Fangfang Yu, Bomin Sun, Denis Tremblay, Hyelim Yoo, Anthony Reale
ECMWF: Samuel Quesada Ruiz
Samuel Quesada Ruiz (ECMWF)：GEO imager's IR channel bias monitoring at ECMWF
Samuel exploited GEO Window Channel radiance observations by analyzing O-B statistics. He found that window channel radiances observed by different GEO instruments have different statistical characteristics (due to varying spectral response and systematic aspects of the underlying surface that they are exposed to). The results suggested a model bias in the ECMWF diurnal cycle of ocean skin temperature. He also compared Met-9 and Met-8 based on operational monitoring statistics.
Tim: You mentioned the bias is related to model bias, caused by SST? Can you explain more?
R: Slide 11 gives more information. The bias patterns are consistent for all the satellites. We think this is caused by the model surface temperature bias.
Fangfang commented that they did not find diurnal calibration issues for GOES-ABI.
Likun Wang: Why did you only focus on the window channels?
R: Because we use window channels for QA in the data assimilation. This channel has important information for model surface information.
Tim: Did you check the results during other periods?
R: Slide 11 give the results in July 2021. We also checked the results during different time. But the bias patterns are quite similar.
Munn Shukla (ISRO) : Inter-calibration of INSAT-3DR
Munn Shukla investigated calibration anomaly in INSAT-3D/3DR IR Imager during mid-night and satellite Yaw-flip. From GSICS results, he found system behavior changes after each flip. Empirical correction coefficients are derived for each flip duration. Root cause analysis is still to be done.
Q: INSAT-3DR stability much better than INSAT-3D in recovery from yaw-flip. Any changes to design?
R: Instrument design are improved.
A lot of discussion on underlying mechanism, incluidng spatial distribution of space view count, sensitivity to mirror angle/reflectivity, sensitivity to mirror angle/reflectivity, variations in detector temperature, and stray light in BB, ... etc.