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Please note that we have uploaded a new amsua_clparams.dat file to https://nwp-saf.eumetsat.int/downloads/aapp_data_files/atovs_cal_files/. The calibration counts of Metop-C channels 4, 5 and 8 were dropping below the lower limits. Additionally, scanlines were rejected on the basis of failing scan-to-scan consistency checks. This update addresses both issues, ensuring locally processed data is not lost due to overly stringent quality control measures.
As usual, you can use the get_atovs_cal_files.sh script to download and install the new file, if you wish.
Nigel and Elisabeth
Subject: Inquiry regarding the new amsua_clparams.dat
Dear Nigel and Elisabeth,
Thank you for updating the calibration file. We are currently testing the new amsua_clparams.dat file in our processing system.
During our verification, we noticed a difference in the results for Metop-C AMSU-A channel 3, which was not explicitly mentioned in your announcement (as you specifically noted channels 4, 5, and 8). Could you please confirm whether this difference is due to changes made to the scan-to-scan consistency QC thresholds?
Additionally, we found that the Space View Count lower limit for Metop-B AMSU-A channel 3 also appears to have been modified, although this was not mentioned in the post either. (Note: Our processing results for Metop-B remained unchanged overall.) Could you please confirm if this change to Metop-B was intentional?
Thank you for your time and assistance.
Best regards,
Nozomi HATA /JMA
Dear Nozomi HATA,
Thank you for your careful checking. I can confirm that these changes were intended. The complete list is:
- Updated Metop-B channels 3 and 6 warm and cold minimum limits.
- Updated Metop-C channels 4, 5 and 8 warm minimum limits.
- Updated Metop-C channels 3, 4, and 8 scan-to-scan consistency thresholds (max change in mean counts from previous scan allowed). These were required to eliminate related warnings in amsuacl.log output.
Metop-B Channel 3 was adjusted in order to avoid issues in the near future as the counts drift. Yes, the consistency thresholds will have a small effect on the brightness temperatures as some valid samples were previously being discarded.
Nigel
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