Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Retrieval of SCIAMACHY limb measurements: First Results A. Rozanov, V. Rozanov, and J. P. Burrows

Overview  CDI radiative transfer model  Linearisation/Weighting functions  Retrieval procedure  Results  Ozone  NO 2  BrO  OClO

CDI Radiative transfer model Approximate spherical solution (limb geometry): Solution: Pseudo-spherical radiation field:

Linearization of RTM Taylor series expansion: Weighting function definition: Linearized RTM in vector form:

Pseudo-spherical weighting functions Differentiating the pseudo-spherical RTE: Equation for pseudo-spherical weighting functions:

Spherical weighting functions Differentiating the spherical RTE: Equation for spherical weighting functions:

Weighting function comparison 325 nm, 30 km tangent height600 nm, 20 km tangent height

Shift and squeeze for reference spectrum with respect to limb spectrum Shift and squeeze for modeled spectrum with respect to measured limb spectrum Scaling factors for correction spectra OUTPUT Vertical distributions or total columns of atmospheric trace gases Averaging kernels Precision information OUTPUT Limb radiance at a particular tangent height Limb radiance at a reference tangent height as irradiance Ratios of modeled limb spectra to the spectrum at a reference tangent height Correction spectra (Ring, tilt, offset, etc.) INPUT Measured and modeled limb radiances with all corrections from pre-fit routine applied Weighting functions from RTM A priori information INPUT Retrieval procedure Tangent height correction with “Knee Method” Shift and squeeze correction (at each tangent height in the selected tangent height range) Vertical profile retrieval (optimal estimation) INPUT: Limb radiance from 295 to 305 nm OUTPUT: Tangent height correction

Ozone, spectral fits Spectral region: – 308 nm, 470 – 585 nm Tangent height region: 10 – 55 km (UV), 7 – 45 km (visible) 31 km tangent height24 km tangent height

Ozone, comparison with HALOE 7 July November 2002

Ozone, comparison with Ozone Sondes 24 July 2002, Ny-Alesund 6 November 2002, Hohenpeissenberg

NO 2, spectral fit Spectral region: 420 – 455 nm Tangent height region: 15 – 40 km 24 km tangent height

NO 2, comparison with HALOE 22 July 2002 (SZA = 67 deg)25 July 2002 (SZA = 49 deg)

BrO retrieval 11 January 2003 (63 o N, 65 o E) Vertical profileSpectral fit at 21 km tangent height

OClO retrieval 11 January 2003 (63 o N, 65 o E) Vertical profileSpectral fit at 21 km tangent height

Summary and Outlook  Radiative transfer model linearized with respect to gases  Retrieval algorithm  Good agreement with other instruments for O 3 and NO 2  Reasonable profiles and spectral fits for BrO and OClO To be done:  Weighting functions for scattering and albedo  Extended validation of O 3 and NO 2  Comparison of BrO and OClO profiles with independent measurements