Seminar on Physics and Chemistry of the Atmosphere (Abstract)

Aerosol Classification by Simultaneous Star-Photometer and Raman Lidar Measurements

D. Kaiser¹, V. Novikov², D. Müller³, U. Leiterer⁴, F. Immler¹ and O. Schrems¹

¹ Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany
² Central Astronomical Observatory of the Russian Academy of Sciences, Pulkovo, Russia
³ Institute for Tropospheric Research, Leipzig, Germany
⁴ Meteorological Observatory Lindenberg of the German Weather Service, Lindenberg, Germany

03.06.2005, 13.00 c.t.
Room S3120

Aerosol Particles (AP) are one of the largest uncertainties in climate forcing assessment. Highly variable concentrations in the atmosphere and numerous types of AP make the monitoring of the atmospheric aerosol a difficult problem. In-situ measurements are very reliable but do in general not provide the total optical depth. Satellite measurements provide global coverage but have a limited scope and accuracy.

Ground-based measurements with Photometer and Lidar deliver total column (Photometer) and profile (Lidar) aerosol optical properties, which allow for the derivation of size distribution, refractive index, scattering function and Single Scattering Albedo. The inversion algorithms have been compared to in-situ measurements in some single cases and shown good agreement (Masonis 2002, Müller 2001).

Star-Photometer and Raman Lidar measurements have been made simultaneously during the measurement campaigns MARL@MOL2003 and LITFASS2003 in Lindenberg, Germany from May to September 2003. The spectral resolution of the star-photometer (9 wavelengths) and Raman Lidar extinction, backscatter and depolarisation profiles allow for an extended characterisation of AP.

Extinction coefficients can not be measured from the ground, as emitted laser beam and telescope field-of-view do not overlap completely. A calculation of the exact overlap function has been made ("overlap correction") to extend the range of extinction profiles down to 2 km above the ground depending on atmospheric conditions. The total OD including the 2 lowermost km of the atmospheric aerosol can by measured with Star-Photometer.

Optical and Microphysical Properties of three days are analysed at different altitudes. A comparison of the two instruments shows good agreement in many cases. Star-Photometer and Raman Lidar (SPLI) can be fruitfully combined to study AP.