München 2004 – wissenschaftliches Programm
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UP: Umweltphysik
UP 15: Poster: Die „Atmosph
äre“ im Labor
UP 15.2: Poster
Dienstag, 23. März 2004, 14:00–16:00, Schellingstr. 3
Gas Exchange Experiments using time resolved UV-Spectroscopy — •Kai Degreif1,2 and Bernd Jähne1,2 — 1Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Im Neuenheimer Feld 368, D-69120 Heidelberg — 2Institut für Umweltphysik, Im Neuenheimer Feld 229, D-69120 Heidelberg
The air sea gas exchange plays a key role in the development of the earth’s climate. The oceans can act as a source or sink for climate relevant gases such as carbon dioxide, methane or dimethyl sulphide. Hydrodynamics in the viscous boundary layer at the free ocean surface and therefore the gas transfer across the interface are not well understood yet and require precise measurements with multiple tracers. UV-spectroscopy is introduced as a new technique for direct and fast measurements of multiple tracer concentrations both in the water and the atmosphere. Volatile aromatic hydrocarbons such as benzene, thiophene, pyridine and derivates and some other species can be measured. The new technique is attractive for two reasons: a) concentrations of volatile species dissolved in water can be measured directly in the water without the need for extraction and b) tracers with a wide range of physicochemical parameters, i.e. Schmidt number and solubility can be measured simultaneously so that a detailed experimental study of the influence of these parameters on air-water gas exchange becomes feasible. The experimental set up and analysis of the spectral data are described. First results from experiments in a 120 cm diameter circular wind-wave-facility in Heidelberg show the significant potentiality of the new technique.