ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-2813-2010 On retrieval of lidar extinction profiles using Two-Stream and Raman techniques Stachlewska I. S. 1 2 Ritter C. 1 Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, 14473 Potsdam, Germany Institute of Geophysics, Faculty of Physics, University of Warsaw, Pasteura 7, 02-093 Warsaw, Poland 25 03 2010 10 6 2813 2824 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/2813/2010/acp-10-2813-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/2813/2010/acp-10-2813-2010.pdf

The Two-Stream technique employs simultaneous measurements performed by two elastic backscatter lidars pointing at each other to sample into the same atmosphere. It allows for a direct retrieval of the extinction coefficient profile from the ratio of the two involved lidar signals. During a number of Alfred-Wegener-Institute (AWI) campaigns dedicated to Arctic research, the AWI's Polar 2 aircraft with the integrated onboard nadir-pointing Airborne Mobile Aerosol Lidar (AMALi) was utilised. The aircraft flew over a vicinity of Ny Ålesund on Svalbard, where the zenith-pointing Koldewey Aerosol Raman Lidar (KARL) has been located. This experimental approach gave the unique opportunity to retrieve the extinction profiles with a rarely used Two-Stream technique against a well established Raman technique. Both methods were applied to data obtained for clean Arctic conditions during the Arctic Study of Tropospheric clouds and Radiation (ASTAR 2004) campaign, and slightly polluted Arctic conditions during the Svalbard Experiment (SvalEx 2005) campaign. Successful comparison of both evaluation tools in different measurement conditions demonstrates sensitivity and feasibility of the Two-Stream method to obtain particle extinction and backscatter coefficients profiles without assumption of their relationship (lidar ratio). The method has the potential to serve as an extinction retrieval tool for KARL or AMALi simultaneous observations with the space borne CALIPSO lidar overpasses during the ASTAR 2007.

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