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Introduction into the Absorption Channels

Introduction into the Absorption Channels. Description of characteristics and content of the Ozone channel: Ch08: 9.7 . Contact person: Veronika Zwatz-Meise zwatz-meise@zamg.ac.at Version 1.0. 13 July 2004. All MSG channels. Channel 01: VIS 0.6  Channel 02: VIS 0.8 

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Introduction into the Absorption Channels

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  1. Introduction into the Absorption Channels Description of characteristics and content of the Ozone channel:Ch08: 9.7  Contact person: Veronika Zwatz-Meise zwatz-meise@zamg.ac.at Version 1.0. 13 July 2004

  2. 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)

  3. „Ozone channel“Ch08: 9.7 m

  4. Ch08: 9.7 Sun radiation Earth radiation Watt/ m2 and micron Ozone Carbon dioxid Water vapour Wavelength (micron)

  5. 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

  6. 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

  7. Ch08 is in the centre of the O3 absorption band around 9  Energy spectrum Source:EUMETSAT Ch08

  8. Signals from lower parts of troposphere; But: Secondary maximum from higher than 100 hPa Weighting functions Source:EUMETSAT Figure 3c

  9. Signals from lower parts of troposphere; But: Secondary maximum from higher than 100 hPa Weighting functions Source:EUMETSAT Figure 3d

  10. 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

  11. „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

  12. 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

  13. MTP: WV

  14. WV 6.2 MSG: Ch05, WV 04 December 02/ 12.30 UTC

  15. O3 9.7 MSG: Ch08,Ozone 04 December 02/ 12.30 UTC

  16. Maximum of shear vorticity at 300

  17. PV = 2 (tropopause) lower than 450 hPa

  18. Confluence at 500 and 300 hPa

  19. 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

  20. MSG: Ch08,Ozone

  21. MSG: Ch09, IR

  22. MSG: Ch05, WV

  23. At cyclonic side of jet streak at 300

  24. Maximum of shear vorticity at 300

  25. PV = 2 (tropopause) lower than 450 hPa

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