Introduction into the
Absorption Channels
Description of characteristics and
content of the CO2 channel:
Ch11: 13.4 
Contact person:
Veronika Zwatz-Meise
[email protected]
Version 1.0. 13 July 2004
1
All MSG channels
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Channel 01:
Channel 02:
Channel 03:
Channel 04:
Channel 05
Channel 06:
Channel 07:
Channel 08:
Channel 09:
Channel 10:
Channel 11:
Chanell 12:
VIS 0.6 
VIS 0.8 
NIR 1.6 
MIR 3.9 
WV 6.2 
WV 7.3 
IR 8.7 
IR 9.7  („Ozon“)
IR 10.8 
IR 12.0 
IR 13.4  („CO2“)
HRV (High Resolution Visible)
2
„CO2 channel“
Ch11: 13.4 m
3
Ch11: 13.4 
Sun radiation
Earth radiation
Watt/
m2 and
micron
Ozone
Carbon
dioxid
Water
vapour
Wavelength (micron)
4
Comparison of radiation sources
sun - earth
• For wave length < 5 m solar radiation is dominant
• For wave length > 5 m radiation of earth is dominant
• Ch01, 02, 03, 12: only sun radiation
• Ch04: both: radiation from sun and earth
• Ch 05, 06, 07, 08, 09, 10, 11: only thermal earth radiation
Sun radiation
Earth radiation
Watt/
m2
and
micron
only
VIS
VIS +
IR
only
IR
5
Energy
spectrum
Source:
EUMETSAT
Ch11
• Ch11 is in the wing of the CO2 absorption band around 15 m
6
Maximal signal from around 870 hPa
Weighting
functions
Source:
EUMETSAT
7
Weighting
functions
Source:
EUMETSAT
Maximal signal from around 820 hPa
Figure 3d
8
Application areas for the CO2 channel
• Qualitative application of images:
– No additional features compared to the IR window
channels
– No special application for qualitative image interpretation
(at the time being)
• Quantitative applications:
– temperature profiles
– instability
– winds
9
Ch11:13.4
10
Ch09:10.8
11
Ch10:12.0
12