Multiple scattering by aerosols as seen from CALIPSO - a Monte-Carlo modelling study.

The impact of multiple scattering (MS) by aerosols on satellite-borne lidar measurements is studied by Monte-Carlo radiative transfer simulations. A total of 48 aerosol scenarios are considered. We find that the frequently used MS correction factor can be parameterized as a function of aerosol size and aerosol optical depth. Its dependencies on vertical distribution and total optical depth can be treated as a random error. We illustrate the use of our parameterization by considering an episode of high sea salt concentrations over the ocean. Neglecting MS, or using a constant value of the MS correction factor, can introduce a negative bias in the computed backscattered power that exceeds the random error in our approach.