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

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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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?

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

14-16 April 2003 Limb Workshop, Bremen 6

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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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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Outlook

• Investigate sensitivity to the choice of reference spectrum

• Further optimise the fitting range

• ….whatever more we learn here!