Search for OClO signatures from Odin limb radiance measurements using DOAS technique
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Transcript of Search for OClO signatures from Odin limb radiance measurements using DOAS technique
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14-16 April 2003 Limb Workshop, Bremen 1
Search for OClO signatures from Odin limb radiance measurements
using DOAS technique
P.Krecl, J.Stegman, C.S.Haley, C.E.Sioris, D.P.Murtagh, S.Brohede,
E.J.Llewellyn and the Odin Team
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14-16 April 2003 Limb Workshop, Bremen 2
DOAS parameters applied:
O3 223K Voigt et al
NO2 223K Voigt et alOClO 233K Kromminga et alBrO 223K Fleishman et alRing 250K Chance et alRayleigh Witt et alReference spectrum: 63 co-added spectra TH>55kmSpectral range: 348 – 382 nm, hw1e 0.48 nmBox-car smoothing: 25-pixel widthOrbits: 2175 (Sept 16, 2002) and 2226 (Oct 1, 2002)
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14-16 April 2003 Limb Workshop, Bremen 3
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Conclusions and outlook
• Clear signatures of OClO found
• But only qualitative results – ongoing work
• Further optimisiation of DOAS algorithm still needed
• Broad versus narrow spectral region?
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14-16 April 2003 Limb Workshop, Bremen 5
Toward validation of DOAS ozone retrievals in the UV-Vis
region
B. Karlsson, P.Krecl, J.Gumbel, J.Stegman, I.McDade,C.S.Haley
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Approach:
• Retrieved ozone profiles (and sza, ssa) plugged in a FM to obtain limb spectra
• Two FM compared: differences <5%
• Slant column densities in DOAS sense retrieved
• Apparent slant column densities compared
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14-16 April 2003 Limb Workshop, Bremen 7
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14-16 April 2003 Limb Workshop, Bremen 8
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14-16 April 2003 Limb Workshop, Bremen 9
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Summary
• Ozone DOAS retrievals 20-30% lower than the present Flittner product
• Higher discrepancy for high ozone
• No clear correlation with albedo, sza,
• Sensitivity to the short wavelength limit of the fitting range
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14-16 April 2003 Limb Workshop, Bremen 11
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14-16 April 2003 Limb Workshop, Bremen 12
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Outlook
• Investigate sensitivity to the choice of reference spectrum
• Further optimise the fitting range
• ….whatever more we learn here!