14-16 April 2003Limb Workshop, Bremen1 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 2003Limb Workshop, Bremen2 DOAS parameters applied: O 3 223KVoigt et al NO 2 223KVoigt et al OClO233KKromminga et al BrO223KFleishman et al Ring250KChance et al RayleighWitt et al Reference spectrum: 63 co-added spectra TH>55km Spectral range: 348 – 382 nm, hw1e 0.48 nm Box-car smoothing: 25-pixel width Orbits: 2175 (Sept 16, 2002) and 2226 (Oct 1, 2002)

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14-16 April 2003Limb Workshop, Bremen4 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 2003Limb Workshop, Bremen5 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 2003Limb Workshop, Bremen6 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 2003Limb Workshop, Bremen10 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 2003Limb Workshop, Bremen13 Outlook Investigate sensitivity to the choice of reference spectrum Further optimise the fitting range ….whatever more we learn here!