The author notes that the numerical approach employed in the development of the truncated geometric approximation was inspired by Prof. Saul Rappaport’s application of a similar approach in the diffraction approximation (DeVore et al. 2009). The author thanks an anonymous reviewer who recommended starting the derivation of the truncated geometric approximation by considering the extinction efficiency rather than directly with the cross section; this both simplified and clarified the derivation. The author is pleased to acknowledge the NASA Science Mission Directorate and Dr. Hal Maring for their support through Research Opportunities in Space and Earth Science (ROSES) Grant NNX08AJ89G. The author also thanks Dr. Brent Holben and his staff for their work in establishing and maintaining AERONET and especially the site at Goddard Space Flight Center.
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