Hamburg 2009 – scientific programme

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UP: Fachverband Umweltphysik

UP 10: Poster: Umweltphysik

UP 10.24: Poster

Thursday, March 5, 2009, 17:48–19:00, VMP 9 Poster

The influence of scattering and absorption processes in sea water on atmospheric radiation - results from ship-borne DOAS measurements — •Anja Schönhardt, Folkard Wittrock, Andreas Richter, Henning Kirk, Hagen Schulte i.d.B, and John P. Burrows — Institut für Umweltphysik, Universität Bremen, Deutschland

Absorption and inelastic scattering within water can influence the upwelling radiation over water bodies. If not identified properly, these effects impact on absorption measurements of trace gases when using nadir observations. Spectral correlations lead to incorrect trace gas amounts and reduced retrieval quality. This presentation reports on Differential Optical Absorption Spectroscopy (DOAS) measurements from a Polarstern cruise in April-May 2008 from South America to Europe. Scattered sun light was measured by two spectrometer units in the visible and UV spectral regions. The light collecting telescope was viewing alternately in different elevation angles: into zenith-sky and at slant angles above and especially below the horizon, intentionally viewing into the ocean water. The DOAS measurements were analysed in different spectral windows to identify structures not associated to well-known effects. Such persistent structures were indeed found in spectra at water viewing angles and may be caused by inelastic scattering at water molecules, by effects from substances in the water (particles, organics, etc) or by processes yet unknown. Analysing these structured residuals helps to characterise the disturbance of optical absorption measurements caused by light transmission through sea water.