Introduction into the Window Channels

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Introduction into the Window Channels

• Description of characteristics and content of the
  channelsCh07 8.7 ?
• Ch09 10.8 ?
• Ch10 12.0 ?

Contact person Veronika Zwatz-Meise zwatz-meise_at_z
amg.ac.at Version 1.0. 13 July 2004
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All MSG channels

• Channel 01 VIS 0.6 ?
• Channel 02 VIS 0.8 ?
• Channel 03 NIR 1.6 ?
• Channel 04 MIR 3.9 ?
• Channel 05 WV 6.2 ?
• Channel 06 WV 7.3 ?
• Channel 07 IR 8.7 ?
• Channel 08 IR 9.7 ? (Ozon)
• Channel 09 IR 10.8 ?
• Channel 10 IR 12.0 ?
• Channel 11 IR 13.4 ? (CO2)
• Chanell 12 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 lt 5 ?m solar radiation is
  dominant
• For wave length gt 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 SourceEUMETSAT
Ch07
Ch09
Ch10

• Ch07, 09, 10 in window region
• Therefore no fundamental attenuation of the
  radiation through absorption

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Max. signal in the window channels from the
surface and lower part of troposphere
Weighting functions SourceEUMETSAT
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
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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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Ch078.7
12
Ch0910.8
13
Ch1012.0
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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_at_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