The May/June 2008 Saharan dust event over Munich: Intensive aerosol parameters from lidar measurements

Abstract

At the end of May 2008 one of the strongest Saharan dust outbreaks ever reached Central Europe. This event gave us the opportunity to extend our series of studies on Saharan dust characterization, which includes measurements near the source (SAMUM‐1, Morocco) and in the regime of mid range transport (SAMUM‐2, Cape Verde). The optical properties of the aerosol particles as a function of time and height are derived from data of the two Raman depolarization‐lidar systems MULIS and POLIS at Munich and Maisach (Germany), respectively. Measurements include the extensive properties of the particles, backscatter coefficient bp and extinction coefficient ap, and the intensive particle properties, linear depolarization ratio dp and lidar ratio Sp. All quantities are derived at two wavelengths, l = 355 nm and l = 532 nm. The focus of the study is on the intensive properties, for which we found on average dp = 0.30 at 355 nm and dp = 0.34 at 532 nm. The systematic errors were typically larger than the dp‐difference at the two wavelengths. With respect to the lidar ratio, we found Sp = 59 sr for both wavelengths, with an uncertainty range between ±4 sr and ±10 sr. These values are quite similar to the results from the SAMUM campaigns. Thus, our results suggest that the intensive optical properties of Saharan dust do not change significantly if the transport time is less than one week. However, more case studies in the far‐range regime are required to scrutinize this statement. To further refine conclusions with respect to the wavelength dependence of dp a further reduction of the errors is desired.