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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, D10S11, doi:10.1029/2004JD005124, 2005

Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations

Christopher Cattrall

Remote Sensing Group, University of Arizona, Tucson, Arizona, USA


John Reagan

Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona, USA


Kurt Thome

Remote Sensing Group, University of Arizona, Tucson, Arizona, USA


Oleg Dubovik

NASA Goddard Space Flight Center, Greenbelt, Maryland, USA


Abstract

The lidar (extinction-to-backscatter) ratios at 0.55 and 1.02 μm and the spectral lidar, extinction, and backscatter ratios of climatically relevant aerosol species are computed on the basis of selected retrievals of aerosol properties from 26 Aerosol Robotic Network (AERONET) sites across the globe. The values, obtained indirectly from sky radiance and solar transmittance measurements, agree very well with values from direct observations. Low mean values of the lidar ratio, Sa, at 0.55 μm for maritime (27 sr) aerosols and desert dust (42 sr) are clearly distinguishable from biomass burning (60 sr) and urban/industrial pollution (71 sr). The effects of nonsphericity of mineral dust are shown, demonstrating that particle shape must be taken into account in any spaceborne lidar inversion scheme. A new aerosol model representing pollution over Southeast Asia is introduced since lidar (58 sr), color lidar, and extinction ratios in this region are distinct from those over other urban/industrial centers, owing to a greater number of large particles relative to fine particles. This discrimination promises improved estimates of regional climate forcing by aerosols containing black carbon and is expected to be of utility to climate modeling and remote sensing communities. The observed variability of the lidar parameters, combined with current validated aerosol data products from Moderate Resolution Imaging Spectroradiometer (MODIS), will afford improved accuracy in the inversion of spaceborne lidar data over both land and ocean.

Received 13 June 2004; accepted 3 March 2005; published 3 May 2005.

Keywords: aerosol; lidar; remote sending.

Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906); 1640 Global Change: Remote sensing (1855); 1626 Global Change: Global climate models (3337, 4928).

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Citation: Cattrall, C., J. Reagan, K. Thome, and O. Dubovik (2005), Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations, J. Geophys. Res., 110, D10S11, doi:10.1029/2004JD005124.