Hamburg 2009 – scientific programme
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UP: Fachverband Umweltphysik
UP 10: Poster: Umweltphysik
UP 10.4: Poster
Thursday, March 5, 2009, 17:48–19:00, VMP 9 Poster
Cavity Enhanced DOAS - Instrument design and theory — •Jan Meinen1,2, Jim Thieser3, Denis Pöhler2, Ulrich Platt2, and Thomas Leisner1,2 — 1Institute for Meteorology and Climate Research, Aerosols and Heterogeneous Chemistry in the Atmosphere (IMK-AAF), Forschungszentrum Karlsruhe GmbH, Germany — 2Institut for Environmental Physics (IUP), Atmosphere and Remote Sensing, Ruprecht-Karls-Universität Heidelberg, Germany — 3Max-Planck-Institut für Chemie, Division of Atmospheric Chemistry, Mainz, Germany
Cavity enhanced methods in absorption spectroscopy have seen a considerable increase in popularity during the past decade. Especially Cavity Enhanced Absorption Spectroscopy (CEAS) established itself in atmospheric trace gas detection by providing tens of kilometers of effective light path length using a cavity as short as 1 m. This device combines the small size of the cavity with the enormous advantages of the DOAS approach in terms of sensitivity and specificity, and lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the Cavity Enhanced-DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light path by the trace gas absorption, since cavity losses due to absorption by gases reduce the quality of the cavity. We show the basic concept of a Cavity Enhanced-DOAS instrument, discuss the relationships caused by the light path reduction and present methods to correct the obtained trace gas concentrations.