HR: 08:45h
AN: A11F-04    [Abstracts]
TI: A Phillips-Tikhonov Based Carbon Dioxide Retrieval Algorithm: Technique and First Validation Results
AU: * Butz, A
EM: a.butz@sron.nl
AF: SRON - Netherlands Institute for Space Research, Sorbonnelaan 2, Utrecht, 3584 CA, Netherlands
AU: Hasekamp, O P
EM: O.P.Hasekamp@sron.nl
AF: SRON - Netherlands Institute for Space Research, Sorbonnelaan 2, Utrecht, 3584 CA, Netherlands
AU: Frankenberg, C
EM: C.Frankenberg@sron.nl
AF: SRON - Netherlands Institute for Space Research, Sorbonnelaan 2, Utrecht, 3584 CA, Netherlands
AU: Aben, I
EM: E.A.A.Aben@sron.nl
AF: SRON - Netherlands Institute for Space Research, Sorbonnelaan 2, Utrecht, 3584 CA, Netherlands
AB: Space borne remote sensing measurements of the atmospheric CO₂ column have become feasible recently through the SCIAMACHY instrument aboard ESA's Envisat platform. Nadir observations of near-infrared solar radiation backscattered from the Earth's surface and atmosphere allow for CO₂ column retrievals with sensitivity down to surface level. In the near future, dedicated space missions such as the OCO and GOSAT instruments aim at retrieving atmospheric CO₂ columns with an accuracy that facilitates the determination of CO₂ sources and sinks on regional scales. We present a retrieval algorithm based on a Phillips-Tikhonov regularization scheme that targets at the retrieval of CO₂ column abundances from these different remote sensing platforms. The algorithm retrieves the vertical profile of CO₂ by minimizing the least-squares difference between the observed spectrum and the forward model given the norm of the retrieved profile as side-constraint. In a first exercice, we retrieved CO₂ abundances with 1 to 2 degrees of freedom from nadir measurements of SCIAMACHY in the near-infrared spectral range assuming a non-scattering atmosphere. These satellite retrievals are compared to coinciding direct sun observations over Park Falls, Wisconsin, USA, performed at very high spectral resolution by a ground-based FTS within the TCCON network. Applying our retrieval algorithm to the ground-based FTS spectra yields the vertical CO₂ profile with 3 to 4 degrees of freedom. Our approach provides a full characterization of ground-based and satellite retrievals through the respective averaging kernel matrices making thorough validation studies possible. Preliminary results show promising agreement between the CO₂ columns retrieved from both sensors. In the future, we plan to refine our algorithm by simultaneously retrieving CO₂ abundances and aerosol properties in a scattering atmosphere. More extensive validation studies are necessary to improve the algorithm and to gain an estimate of the accuracy of the CO₂ retrievals.
DE: 0365 Troposphere: composition and chemistry
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3360 Remote sensing
DE: 3394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting