Global Representation of Aerosol Vertical Profiles by Sums of Log-normal Modes: Consequences for the Passive Remote Sensing of Aerosol Heights
Journal of Geophysical Research: Atmospheres, (2014)DOI: 10.1002/2014JD021472
Abstract
Aerosol extinction profiles from a climatology of CALIPSO measurements are analysed with respect to their representation by truncated sums of up to three log-normal functions. Discussed are results for the climatological mean and a realistic profile, which is constructed from the climatological mean and its standard deviation. The realistic profile shows in general a more feature rich structure and is used as proxy for actual measurements. It was found, that a single log-normal mode is on global scale able to explain 59% of the vertical profile, while a sum of two modes is able to explain 74%. Including a third log-normal mode leads only to a minor improvement to 79%. The strong regional and weaker seasonal dependency of the reconstruction accuracy with respect to the number of used log-normal modes is presented and discussed in detail. These findings have implications for the design of future operational aerosol height retrievals for upcoming instruments such as TROPOMI onboard ESA's Sentinel 5 precursor or Sentinel 4.