Introduction into the
Window Channels
Description of characteristics and
content of the channels:
Ch07: 8.7 
Ch09: 10.8 
Ch10: 12.0 
Contact person:
Veronika Zwatz-Meise
zwatz-meise@zamg.ac.at
Version 1.0. 13 July 2004
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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)
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Ch07: 8.7 
Ch09: 10.8 
Ch10: 12.0 
Sun radiation
Earth radiation
Watt/
m2 and
micron
Ozone
Carbon
dioxid
Water
vapour
Wavelength (micron)
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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
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Energy
spectrum
Source:
EUMETSAT
Ch07
Ch09 Ch10
• Ch07, 09, 10 in window region
• Therefore: no fundamental attenuation of the radiation through absorption
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Weighting
functions
Source:
EUMETSAT
Max. signal in the window channels from
the surface and lower part of troposphere
Figure 3c
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Application areas for the window channels
• Recognition of cloud systems because of the thermal
radiation of cloud and earth surface
• Extraction of high thin Cirrus from the whole cloud
systems
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Ch07: 8.7
8
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Some characteristica: Ch07: 8.7
• Indicative for high, thin
Cirrus cloud
– improved recognition of
Cirrus
– best use through preparation
of RGBs and differences
• Support for discrimination
between ice- and water
cloud
• From optical point of view
(at the time being) no
typical new features
recognisable
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Ch07:8.7
11
Ch09:10.8
12
Ch10:12.0
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Ch09: 10.8 and Ch10: 12.0
These channels are comparable to the
relevant NOAA channels
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Sun radiation
Earth radiation
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Some characteristica: Ch09: 10.8 and Ch10: 12.0
• Usual evaluation of cloud
in both channels
• Not much difference
between the apperance in
the three window channels
• Ch10 is more sensitive for
high thin Cirrus
– not easy to recognise
through checking by eyes
– difference images give
information
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Ch07: 8.7
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Ch09: 10.8
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Ch10: 12.0
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Split window Ch09: 10.8 and Ch10: 12.0
• Ch10 is more sensitive for
high thin Cirrus
– not easy to recognise
through checking by eyes
– difference images give
information
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Different Absorption of Ice- and Watercloud
between 10.8 and 12.0 m
Higher absorption in the ice phase in 12.0
Absorption of Ice- and
Water cloud
After Source:
D. Rosenfeld
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Examples for visualisation of
high Cirrus
Differencen of I07, I09, I10
Source:
Jochen Kerkmann
kerkmann@eumetsat.de
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Difference
I07 - I09
Angola
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Difference
I09 - I10
Angola
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Difference
I07 - I09
S-Atlantic
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Difference
I09 - I10
S-Atlantic
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