Since 2005 a continuous time series of inter-calibration coefficients have been obtained between two Meteosat First Generation satellites and the HIRS instrument onboard the US NOAA-16 and NOAA-17 satellites. The Meteosat IR and WV channels have been compared to HIRS channels 8 and 10, respectively. Results are presented on this page.

It should be noted that this work is not yet directly linked to the GSICS activities, i.e. the inter-calibration criteria are not quite as stringent as they are used for GSICS, which is reflected by the relatively high uncertanties. This work and the corresponding results will slowly merge with the GSICS activities, as time progresses.

An analysis shows: 

• Both the operational and the intercalibration coefficients are currently very stable in time. The intercalibration coefficient shows a little more variability, but that can easily be explained by the variability in different orbits; where the number of possible collocations changes; the time difference between the images varies, and the cloud situation is always different. These variations, however, are much smaller than the uncertainty due to scatter of the local inter-calibration coefficients, as indicated by the error bars.

• The IR coefficients are rather close, and the operational coefficient is almost always within the error bounds of the cross-calibration coefficient. There is, however, a clear indication that the cross-calibration coefficient is a little higher, which accounts for a temperature bias of 2 - 2.5K for Met-7, and 3.0 K for Met-5.
 
• The WV coefficients disagree by about 14% which translates into a temperature of difference of about -3K for Met-7 and Met-5. The reason for the fairly large bias are currently not clear and under study.

Satellite 1: no data Satellite 2: no data Channel: no data Year: no data
	The seasonal variation of the temperature biases resulting from the inter-calibration between the two Meteosat satellites and NOAA-16 and NOAA-17