Measurements of aerosol dimensional distributions and microphysical
characteristics: A comparison between Raman lidar and airborne sensors
Abstract
This manuscript compares aerosol size distributions and microphysical
property measurements from the Raman lidar BASIL and from aircraft
sensors during HyMeX-SOP1. The attention was focused on a measurement
session on 02 October 2012, with BASIL measurements revealing the
presence of a lower aerosol layer extending up to 3.3 km and an elevated
layer with extending from 3.6 km to 4.6 km. Aerosol size distributions
and microphysical characteristics were determined from three-wavelength
particle backscattering and extinction profile measurements through a
retrieval approach based on Tikhonov regularization. A good agreement is
found between BASIL retrievals and the microphysical sensors’
measurements for all considered aerosol dimensional and microphysical
characteristics. Specifically, BASIL and in-situ volume concentration
values are 1-3.5 mm3cm-3 in the
lower layer and 2-4 mm3cm-3 in the
upper layer. Furthermore, effective radius values from BASIL and the
in-situ sensors’ measurements are in the range 0.2-0.6 mm both in the
lower and upper layer. Particle size distributions were determined at
2.2, 2.8, 4 and 4.3 km, with again a good agreement between the Raman
lidar and the microphysical sensors throughout the considered height
interval. These results, in combination with Lagrangian back-trajectory
analyses and chemical composition measurements, indicate that aerosols
below 3 km were possibly originated by forest fires in North America or
by anthropogenic activities in North-Eastern Europe, while aerosols
above 3 km were originated over the North Atlantic and presumably
include both a marine and an organic component. This interpretation is
compatible with the lidar retrieved profiles of particle complex
refractive index.