Retrieving aerosol microphysical properties by Lidar‐Radiometer Inversion Code (LIRIC) for different aerosol types

Abstract

LIRIC (Lidar-Radiometer Inversion Code) is applied to combined lidar and Sun photometer data from Granada station corresponding to different case studies. The main aim of this analysis is to evaluate the stability of LIRIC output volume concentration profiles for different aerosol types, loadings, and vertical distributions of the atmospheric aerosols. For this purpose, in a first part, three case studies corresponding to different atmospheric situations are analyzed to study the influence of the user-defined input parameters in LIRIC when varied in a reasonable range. Results evidence the capabilities of LIRIC to retrieve vertical profiles of microphysical properties during daytime by the combination of the lidar and the Sun photometer systems in an automatic and self-consistent way. However, spurious values may be obtained in the lidar incomplete overlap region depending on the structure of the aerosol layers. In a second part, the use of a second Sun photometer located in Cerro Poyos, in the same atmospheric column as Granada but at higher altitude, allowed us to obtain LIRIC retrievals from two different altitudes with independent Sun photometer measurements in order to check the self-consistency and robustness of the method. Retrievals at both levels are compared, providing a very good agreement (differences below 5 μm 3 /cm 3 ) in those cases with the same aerosol type in the whole atmospheric column. However, some assumptions such as the height independency of parameters (sphericity, size distribution, or refractive index, among others) need to be carefully reviewed for those cases with the presence of aerosol layers corresponding to different types of atmospheric aerosols.

Microphysical characterization of long-range transported biomass burning particles from North America at three EARLINET stations

“…The regions of profiles affected by incomplete overlap and by too-low backscatter ratios are not shown. The β-and α-profiles highlighted that the smoke layers were intense in terms of optical properties, and the low δ P values (less than 4 % for Granada and Warsaw and less than 8 % for Leipzig) indicate the large proportion of spherical, fine-mode particles Granados-Muñoz et al, 2014;.…”

GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures

“…Both algorithms have been tested for a variety of aerosol types and their mixtures. For example, LIRIC has been tested for dust and volcanic aerosols (Wagner et al, 2013), dust-pollution mixture (Tsekeri et al, 2013), dust, pollution and a mixture of dust, smoke and pollution (Granados-Muñoz et al, 2014, 2016aPapayannis et al, 2014) and smoke-pollution mixture (Kokkalis et al, 2017). LIRIC has also been used to study dust transport events and dust modelling performance over Europe (Binietoglou et al, 2015;Granados-Muñoz et al, 2016b), as well as to evaluate air quality models (Siomos et al, 2017).…”

Validation of LIRIC aerosol concentration retrievals using airborne measurements during a biomass burning episode over Athens

“…More precisely, for various atmospheric conditions, lidar geometrical characteristics, and LIRIC's regularization parameters, the uncertainties in the retrieved aerosol parameters were found to be maximum 30%, for cases of complex aerosol structures, however taking values below 10%, during cases of homogeneous aerosol mixing and simple aerosol structures (Granados-Muñoz et al, 2014). Uncertainties due to the regularization parameters were found to be below 2%.…”

“…According to the LIRIC retrievals and the linear particle depolarization ratio (~ 6%) below 2 km, a mixture of fine and coarse particles is observed in the lower part of the atmosphere, while above 2 km mostly fine particles are observed (Figure 6). The usage of constant with height AERONET values in LIRIC retrievals may lead to high uncertainties in the retrieval of the volume concentration profiles, especially in cases with non-homogeneous aerosol mixing (Granados-Muñoz et al, 2014), as observed in this case. 30…”