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UP: Umweltphysik

UP 16: Atmosph
ärische Spurengase und Aerosole: Laboruntersuchungen

UP 16.1: Fachvortrag

Wednesday, March 9, 2005, 15:15–15:30, TU TA201

Intercomparison of Formaldehyde Measurements in an Atmosphere Simulation Chamber — •Jens Bossmeyer^1,2, Theo Brauers¹, Franz Rohrer¹, Eric Schlosser¹, Ralf Tillmann¹, and Robert Wegener¹ — ¹Forschungszentrum Jülich, ICG-II: Troposphäre, D-52425 Jülich, Germany — ²Institut für Umweltphysik, Universität Heidelberg, INF 229, D-69120 Heidelberg, Germany

Atmospheric measurements of formaldehyde (HCHO) with independent instruments often provided inconsistent results. HCHO intercomparison experiments covering typical tropospheric mixing ratios of 1-30 ppbv were conducted under controlled conditions in the atmosphere simulation chamber SAPHIR. We employed two differential optical absorption spectroscopy instruments, one with a xenon arc lamp (XDOAS), the other with a laser as light source (LDOAS), and a wet chemical method based on the Hantzsch reaction. The XDOAS is based on literature absorption cross sections, whereas the Hantzsch instrument was calibrated on liquid standards prior to and after the measurements and the high resolution LDOAS had been calibrated once on the Hantzsch in a previous intercomparison. The scatter plots of the simultaneously recorded time series of all three instruments show excellent linear correlations with r bigger than 0.97. However, the regression line between Hantzsch and XDOAS exhibits a significant slope of 1.3 indicating calibration problems whose origin still has to be identified. The implications for atmospheric HCHO measurements will be discussed.