Aerosol closure study by lidar, Sun photometry, and airborne optical counters during DAMOCLES field campaign at El Arenosillo sounding station, Spain

Guerrero-Rascado, Juan Luís; Andrey, Javier; Sicard, Michaël; Molero, Francisco; Comerón, Adolfo; Pujadas, M.; Rocadenbosch, Francesc; Pedrós, R.; Serrano-Vargas, O.; Gil, Manuel; Olmo, F.J.; Lyamani, H.; Navas-Guzmán, Francisco; Alados-Arboledas, L.

doi:10.1029/2010jd014510

Cited by 8 publications

(6 citation statements)

References 69 publications

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“…This algorithm retrieves the aerosol backscatter coefficient profiles corresponding to the elastic wavelengths assuming a reference height free of aerosol particles and a height independent aerosol lidar ratio for each wavelength. More details can be found in Bravo‐Aranda et al [] and Guerrero‐Rascado et al [, ]. Lidar ratios assumed when applying the Klett–Fernald algorithm to the lidar data are obtained by minimizing the difference between the integral of the aerosol backscatter coefficient profile multiplied by the lidar ratio and the aerosol optical depth provided by AERONET for each wavelength [ Guerrero‐Rascado et al , ].…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2014

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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.

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Section: Methodsmentioning

confidence: 99%

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

et al. 2014

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“…More information regarding this observatory is available in several references (e.g. Prats et al ., ; Córdoba‐Jabonero et al ., ; Guerrero‐Rascado et al ., ; Sorribas et al ., , ; Antón et al ., ; Adame et al ., ).…”

Section: Experimental Devicementioning

confidence: 98%

Role of spheroidal particles in closure studies for aerosol microphysical–optical properties

Sorribas

Olmo

Quirantes

et al. 2015

Quart J Royal Meteoro Soc

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A study has been carried out to assess the discrepancies between computed and observed aerosol scattering and backscattering properties in the atmosphere. The goals were: (i) to analyse the uncertainty associated with computed optical properties when spherical and spheroidal approximations are used, and (ii) to estimate nephelometry errors due to angular truncation and non-Lambertian illumination of the light source in terms of size range, particle shape and aerosol chemical compounds. Mie and T-matrix theories were used for computing light optical properties for spherical and spheroidal particles, respectively, from observed particle size distributions. The scattering coefficient of the fine mode was not much influenced by the particle shape. However, computed backscattering values underestimated the observed values by ∼15%. For the coarse mode, the spheroidal approximation yielded better results than that for spherical particles, especially for backscattering properties. Even after applying the spheroidal approximation, computed scattering and backscattering values within the coarse mode underestimated the observed values by ∼49% and ∼11%, respectively. The angular correction most widely used to correct the nephelometer data was discussed to explore its uncertainty. In the case of the scattering properties within the coarse mode, the change of the computed optical parameter is ∼+8% and for the scattering and backscattering values within the fine mode it is lower than ∼±4% for spherical and spheroidal particles. Additionally, if the spheroidal particles are used to evaluate the aerosol optical properties, the correction must be reconsidered with the aim of reducing the uncertainty found for scattering within the coarse mode. This is recommended for sites with desert dust influence; then the deviation of the computed scattering can be up to 13%.

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“…Therefore, in order to make the different results comparable it is necessary to use a common RH ref value. For this purpose, the Hänel model (Hänel, 1976) is used to parameterize the experimental enhancement factor curves. The general form of the Hänel equation is expressed as…”

Section: Procedures For Selection Of Hygroscopic Growth Case Studiesmentioning

confidence: 99%

“…microphysical properties under high relative humidity conditions. Therefore, hygroscopic growth affects the direct scattering of radiation (Hänel, 1976;Hegg et al, 1996;Titos et al, 2014a;Zieger et al, 2013). Also to be considered are especially the indirect effects, as the affinity of atmospheric aerosols for water vapor is highly related to their ability to act as cloud condensation nuclei (CCN) (Charlson et al, 1992;Feingold and Morley, 2003;Padró et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Hygroscopic growth of atmospheric aerosol particles based on active remote sensing and radiosounding measurements: selected cases in southeastern Spain

et al. 2015

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Abstract. A new methodology based on combining active and passive remote sensing and simultaneous and collocated radiosounding data to study the aerosol hygroscopic growth effects on the particle optical and microphysical properties is presented. The identification of hygroscopic growth situations combines the analysis of multispectral aerosol particle backscatter coefficient and particle linear depolarization ratio with thermodynamic profiling of the atmospheric column. We analyzed the hygroscopic growth effects on aerosol properties, namely the aerosol particle backscatter coefficient and the volume concentration profiles, using data gathered at Granada EARLINET station. Two study cases, corresponding to different aerosol loads and different aerosol types, are used for illustrating the potential of this methodology. Values of the aerosol particle backscatter coefficient enhancement factors range from 2.1 ± 0.8 to 3.9 ± 1.5, in the ranges of relative humidity 60–90 and 40–83%, being similar to those previously reported in the literature. Differences in the enhancement factor are directly linked to the composition of the atmospheric aerosol. The largest value of the aerosol particle backscatter coefficient enhancement factor corresponds to the presence of sulphate and marine particles that are more affected by hygroscopic growth. On the contrary, the lowest value of the enhancement factor corresponds to an aerosol mixture containing sulphates and slight traces of mineral dust. The Hänel parameterization is applied to these case studies, obtaining results within the range of values reported in previous studies, with values of the γ exponent of 0.56 ± 0.01 (for anthropogenic particles slightly influenced by mineral dust) and 1.07 ± 0.01 (for the situation dominated by anthropogenic particles), showing the convenience of this remote sensing approach for the study of hygroscopic effects of the atmospheric aerosol under ambient unperturbed conditions. For the first time, the retrieval of the volume concentration profiles for these cases using the Lidar Radiometer Inversion Code (LIRIC) allows us to analyze the aerosol hygroscopic growth effects on aerosol volume concentration, observing a stronger increase of the fine mode volume concentration with increasing relative humidity.

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Aerosol closure study by lidar, Sun photometry, and airborne optical counters during DAMOCLES field campaign at El Arenosillo sounding station, Spain

Cited by 8 publications

References 69 publications

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

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

Role of spheroidal particles in closure studies for aerosol microphysical–optical properties

Hygroscopic growth of atmospheric aerosol particles based on active remote sensing and radiosounding measurements: selected cases in southeastern Spain

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