Visualisation of oxygen concentration fields in the mass boundary layer by fluorescence quenching

TitleVisualisation of oxygen concentration fields in the mass boundary layer by fluorescence quenching
Publication TypeIn Collection
Year of Publication2007
AuthorsFalkenroth, A, Degreif, K, Jähne, B, Jähne, B
EditorGarbe, CS, Handler, RA
Collection TitleTransport at the Air Sea Interface --- Measurements, Models and Parameterizations
PublisherSpringer Verlag
Publication Languageeng
Abstract

Laser-Induced Fluorescence (LIF) is applied to observe directly the mechanism of gas exchange in the aqueous viscous boundary layer at a free water surface. In order to make dissolved oxygen visible, a new class of fluorescent dyes is used with a life time in the order of microseconds so that the quenching constant for dissolved oxygen is sufficiently high for sensitive measurements. Depth profiles of the O2 concentration near the water surface are obtained by a vertical laser sheet at a rate of 185 frames per second. This technique is capable of a measurement sector up to several centimetres down from the water surface with a resolution in the order of 50-100 um. For a small circular wind/wave facility a correlation between wind speed and gas-exchange rates calculated from the extrapolated mean boundary-layer thickness are presented as well as the results of parallel measurements with a budget method for other gases with known Schmidt numbers.

DOI10.1007/978-3-540-36906-6_4
Citation Keyfalkenroth2007a