Introduction into the Absorption Channels

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Introduction into the Absorption Channels

• Description of characteristics and content of the
  Ozone channelCh08 9.7 ?

Contact person Veronika Zwatz-Meise zwatz-meise_at_z
amg.ac.at
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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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Ozone channelCh08 9.7 ?m
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Ch08 9.7
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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Application areas for the Ozone channel

• Qualitative application of images
• No well-known additional features compared to the
  IR window channels
• But new feature detected White stripes
• Stripes are white in case of the inverted
  presentation of the image
• They are a measure for high stratospheric Ozone
  concentrations which have protruded relatively
  far down into the troposphere
• Quantitative applications
• The computation of quantitative Ozone values will
  be a future task

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Energy spectrum SourceEUMETSAT
Ch08

• Ch08 is in the centre of the O3 absorption band
  around 9 ?

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Signals from lower parts of troposphere But Seco
ndary maximum from higher than 100 hPa
Weighting functions SourceEUMETSAT
Figure 3c
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Signals from lower parts of troposphere But Seco
ndary maximum from higher than 100 hPa
Weighting functions SourceEUMETSAT
Figure 3d
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Ch08 Ozonechannel, 9.66

• Ozone concentration in the lower stratosphere
• is not regarded as a channel with optically
  applicable structures
• But there are in some situations white stripes
  in the areas of the black stripes in WV
• Further there are structures in the cloud free
  sea, best seen in this channel

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White Stripes

• White stripes can only be seen in Ch08, not in
  Chs 09, 10
• They appear in areas of dark stripes in WV (Ch05
  and 06)
• They are accompanied by NWP paramaters typical
  for low tropopause (tropopause folding)
• PV low down (for instance 500 hpa)
• Maximum of shear vorticity at 300 hpa
• on the cyclonic side of a jet streak
• Physical meaning of white stripes
• high content of Ozone which absorbs the radiation
  from below and emitts radiation according to 2 nd
  law of Kirchhoff
• There are many more situations with low
  tropopause (tropopause folding) without the white
  stripe consequently
• White stripes are an optical indication of high
  stratospheric Ozone in upper tropopsheric heights

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Case 4 December 2002

• Black stripe in WV Belgium - W-Alps
  -W-Switzerland - Western Mediterranean
• Same area shows white stripe in Ch08
• Model parameters
• PV 2 unit lower than 400, partly 450 hPa
• confluence area at 500 and 300 hPa
• maximum of shear vorticity

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MTP WV
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WV 6.2
MSG Ch05, WV
04 December 02/ 12.30 UTC
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O3 9.7
MSG Ch08,Ozone
04 December 02/ 12.30 UTC
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Maximum of shear vorticity at 300
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PV 2 (tropopause) lower than 450 hPa
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Confluence at 500 and 300 hPa
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Case 9 July 03/0600 UTC

• Black stripe in WV Atlantic huge low system
• Same area shows white stripe in Ch08
• white stripe not seen in the other IR channels
• Model parameters
• close to jet axis (zeroline of shear vorticity)
  on cyclonic side
• maxima of cyclonic shear vorticity
• PV 1 lower than 450
• in vertical cross section convergence at these
  levels

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MSG Ch08,Ozone
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MSG Ch09, IR
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MSG Ch05, WV
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At cyclonic side of jet streak at 300
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Maximum of shear vorticity at 300
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PV 2 (tropopause) lower than 450 hPa