1. Effect of GSICS calibration on CM SAF‘s cloud products
Anke Kniffka – CM SAF team
DWD
21 September 2010
EUMETSAT Conference, Cordoba, Spain

2. EUMETSAT Conference, Cordoba, Spain
Calibration of SEVIRI IR channels with the help of IASI
Applied in this case for MSG2
Data retrieved from Eumetsat‘s web portal
21 September 2010
EUMETSAT Conference, Cordoba, Spain

3. EUMETSAT Conference, Cordoba, Spain
GSICS calibration curve
21 September 2010
EUMETSAT Conference, Cordoba, Spain

4. EUMETSAT Conference, Cordoba, Spain
Effect on radiance for several channels
Tested on one month of SEVIRI slots (March 2009), hourly resolution
Calibration for MSG2, channels: 3.9, 6.2, 7.3, 8.7, 9.7, 10.8, 12.0, 13.4 in use: all but …
There are also visible channels used in cloud detection!
21 September 2010
EUMETSAT Conference, Cordoba, Spain

5. EUMETSAT Conference, Cordoba, Spain
21 September 2010
EUMETSAT Conference, Cordoba, Spain

6. EUMETSAT Conference, Cordoba, Spain
21 September 2010
EUMETSAT Conference, Cordoba, Spain

7. EUMETSAT Conference, Cordoba, Spain
Products are:
CFC, CTY, CTTPH
Temporal resolution:
instantaneous (hourly) and daily mean data
21 September 2010
EUMETSAT Conference, Cordoba, Spain

8. EUMETSAT Conference, Cordoba, Spain
Cloud Fractional Cover: daily mean
original
calibrated
21 September 2010
EUMETSAT Conference, Cordoba, Spain

9. EUMETSAT Conference, Cordoba, Spain
Negative values:
More clouds with calibration
21 September 2010
EUMETSAT Conference, Cordoba, Spain

10. EUMETSAT Conference, Cordoba, Spain
21 September 2010
EUMETSAT Conference, Cordoba, Spain

11. EUMETSAT Conference, Cordoba, Spain
Cloud mask: statistics individual slot data for March 2009
original
calibrated
Some pixel are flagged as clear now (cloudy before), about twice as much crop up (clear before)
Equally distributed in space
21 September 2010
EUMETSAT Conference, Cordoba, Spain

12. EUMETSAT Conference, Cordoba, Spain
Cloud fraction for different cloud types (based on daily mean for March 2009)
original
calibrated
More cloudy pixel
Noticeable rise of high semitransparent cloud class
21 September 2010
EUMETSAT Conference, Cordoba, Spain

13. EUMETSAT Conference, Cordoba, Spain
original
calibrated
No calibration for visible channels so far -> effect on thresholds for cloud type determination
21 September 2010
EUMETSAT Conference, Cordoba, Spain

14. EUMETSAT Conference, Cordoba, Spain
CTH:
neg. values refer to higher clouds with calibration
21 September 2010
EUMETSAT Conference, Cordoba, Spain

15. EUMETSAT Conference, Cordoba, Spain
21 September 2010
EUMETSAT Conference, Cordoba, Spain

16. EUMETSAT Conference, Cordoba, Spain
To sum up:
º Need for calibration in visible channels
→ Can cause problems with consistency
º Validation with ground based data will be carried out
21 September 2010
EUMETSAT Conference, Cordoba, Spain