Erlangen 2018 – scientific programme

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UP: Fachverband Umweltphysik

UP 9: Poster session

UP 9.5: Poster

Wednesday, March 7, 2018, 16:15–18:15, Orangerie

What can we learn from polarised MAX-DOAS measurements? — Andrés G. Bernal Samacá, •Andreas Richter, André Seyler, Vladimir Rozanov, and John P. Burrows — Institut für Umweltphysik, Universität Bremen, Bremen, Deutschland

Most modern Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments use fibre optics between telescope and spectrometer which are long enough to efficiently mix polarisation states of the collected light. Therefore, polarisation sensitivity of the spectrometer is usually not a problem in MAX-DOAS observations. However, sky-light can be strongly polarised, and even if the instrument is not sensitive to the polarisation of the light, the light paths through the atmosphere vary between photons having different polarisation direction. Therefore, at least in principle, having an instrument that measures the polarisation in addition to the intensity of the incoming light should provide additional information on the vertical distribution of absorbers and also on aerosol loading.

In this presentation, results from one month of polarised MAX-DOAS test measurements in Bremen are reported. The measurements include normal horizon scans as well as scans in the principal plane and in the Almucantar. The measurements for several clear sky episodes are compared to radiative transfer calculations with SCIATRAN and the potential and limitations for improving the information content of MAX-DOAS observations are discussed.