Atmospheric Measurement Techniques Discussions www.atmos-meas-tech-discuss.net 1867-8610 3 4 2010 10.5194/amtd-3-3319-2010 http://www.atmos-meas-tech-discuss.net/3/3319/2010/ http://www.atmos-meas-tech-discuss.net/3/3319/2010/amtd-3-3319-2010.html http://www.atmos-meas-tech-discuss.net/3/3319/2010/amtd-3-3319-2010.pdf 3319 3344 2010-08-09 Intercomparison of CALIOP and MODIS aerosol optical depth retrievals C. Kittaka D. M. Winker david.m.winker@nasa.gov M. A. Vaughan A. Omar L. A. Remer Science Systems and Applications Inc., Hampton, VA, USA NASA Langley Research Center, Hampton, VA, USA NASA Goddard Spaceflight Center, Greenbelt, MD, USA deceased The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is carried on the CALIPSO satellite and has acquired global aerosol profiles since June 2006. CALIPSO is flown in formation with the Aqua satellite as part of the A-train satellite constellation, so that a large number of coincident aerosol observations are available from CALIOP and the MODIS-Aqua instrument. This study compares column aerosol optical depth at 0.532 μm derived from CALIOP aerosol profiles with MODIS-Aqua 0.55 μm aerosol optical depth over the period June 2006 through August 2008. The study is based on the CALIOP Version 2 Aerosol Layer Product and MODIS Collection 5. While CALIOP is first and foremost a profiling instrument, this comparison of column aerosol optical depth provides insight into quality of CALIOP aerosol data. It is found that daytime aerosol optical depth from the CALIOP Version 2 product has a small global mean bias relative to MODIS Collection 5. Regional biases, of both signs, are larger and biases are seen to vary somewhat with season. In northern mid-latitudes, aerosol optical depth from CALIOP is lower, on average, than from MODIS. 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