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Assimilation of GOME ozone profiles

Arjo Segers Henk Eskes Ronald van der A - KNMI, The Netherlands. Assimilation of GOME ozone profiles. Research questions. What is the: quallity of the GOME profiles ? quallity of assimilated ozone fields ? added value of profiles, compared with total columns ?

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Assimilation of GOME ozone profiles

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  1. Arjo Segers Henk Eskes Ronald van der A - KNMI, The Netherlands Assimilation of GOME ozone profiles

  2. Research questions What is the: • quallity of the GOME profiles ? • quallity of assimilated ozone fields ? • added value of profiles, compared with total columns ? in the different parts of the atmosphere: • US : upper stratosphere (ozone maximum) • UTLS : upper troposphere, lower stratosphere • LT : lower troposphere

  3. Ozone profiles from satellite • limb viewing instruments: • high vertical resolution, low horizontal resolution • upper parts of atmosphere only • MLS, SCIAMACHY, GOMOS ? • nadir viewing instruments: • based on altitude dependence of absorption spectra • complete profile, vertical resolution ~5km • large horizontal resolution • GOME, SCIAMACHY

  4. GOME ozone profiles (GOME1 Ozone Profile Retrieval Working Group, final meeting nov 2003, ESRIN)

  5. GOME ozone profiles • OPERA retrieval algorithm • footprints ~ 900 x 100 km • 40 points in vertical, degree of freedom ~5 • kernel representation of retrieved profile: yretr = yapriori + A ( yobs - yapriori ) + e

  6. yretr= yapr + A ( yobs- yapr )

  7. GOME vs sondes (april 2000) • large bias in tropical troposphere • UTLS: rather unbiased, but large standard dev abs. bias std.dev.

  8. Assimilation • TM3 Chemistry-Transport Model: • parameterized ozone chemistry (Cariolle, 'cold tracer') • horizontal resolution 3x2 deg. • 44 layers up to 0.1 hPa (selection of 60 ecmwf layers) • meteorological input from ecmwf • TM3PAS Profile Assimilation: • Kalman filter approach • parameterized covariance matrix

  9. Assimilation of profiles/columns

  10. Conclusions • Quallity of GOME profiles (compared with sondes): • ozone maximum : ok • UTLS : ok at mid latitudes, reasonable in tropics • LT : work in progress ... • Added value of profiles in assimilation: • improved ozone simulation in UTLS at mid latitudes • 'substracted value' : • LT is messed up ...

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