Berlin 2012 – scientific programme

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UP: Fachverband Umweltphysik

UP 14: Atmosphere 2

UP 14.8: Talk

Thursday, March 29, 2012, 16:30–16:45, HFT-FT 131

Advances in CO₂ total column retrieval by mid-IR Fourier-Transform Spectroscopy — •Matthias Buschmann¹, Susanne Dohe², Emmanuel Mahieu³, Nicholas Deutscher¹, Thorsten Warneke¹, and Justus Notholt¹ — ¹Institut für Umweltphysik, Universität Bremen — ²Karlsruhe Institute of Technology (KIT) — ³Université de Liège

Over the last decade ground-based remote sensing measurements of CO₂ have been established as an important component in the global observing system for greenhouse gases. Since 2004 the Total Carbon Column Observing Network (TCCON) sites have provided CO₂ retrievals in the near-IR region, which has several advantages. For example O₂ can be retrieved in the same spectral region and because the O₂ mole fraction is known, the CO₂ signal can be normalized by ratioing, thus systematic errors partly cancel. Additionally there is only one significant interference in the considered spectral window, namely water vapor, allowing analyzing broad spectral windows. CO₂ can also be retrieved in the mid-IR spectral region, but here many gases interfere and no O₂ absorptions are available. However there are 20 years of additional observations obtained in the mid-IR at a suite of FT-IR sites of the Network Detection of Atmospheric Composition Change (NDACC). It would be of great benefit to produce CO₂-data of sufficient precision from the mid-IR spectral region. In this study we have advanced the retrieval of CO₂ from the mid-IR spectral region. Limitations of the approach are outlined and the feasibility of a future CO₂-product of sufficient precision is discussed.