05 Feb 2021

05 Feb 2021

Review status: this preprint is currently under review for the journal ACP.

Overview of SLOPE I and II campaigns: aerosol properties retrieved with lidar and sun-sky photometer measurements

Jose Antonio Benavent-Oltra1,2, Juan Andrés Casquero-Vera1,2, Roberto Román3, Hassan Lyamani1,2, Daniel Pérez-Ramírez1,2, Maria José Granados-Muñoz2,3, Milagros Herrera4, Alberto Cazorla1,2, Gloria Titos1,2, Pablo Ortiz-Amezcua1,2, Andrés Esteban Bedoya-Velásquez2,5, Gregori de Arruda Moreira2,6, Noemí Pérez7, Andrés Alastuey7, Oleg Dubovik4, Juan Luis Guerrero-Rascado1,2, Francisco José Olmo-Reyes1,2, and Lucas Alados-Arboledas1,2 Jose Antonio Benavent-Oltra et al.
  • 1Department of Applied Physics, Universidad de Granada, Granada, Spain
  • 2Andalusian Institute for Earth System Research, IISTA-CEAMA, Granada, Spain
  • 3Group of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, Valladolid, Spain
  • 4Laboratoire d’Optique Atmosphérique (LOA), UMR8518 CNRS, Université de Lille, Villeneuve D’ASCQ, France
  • 5The French AeorospaceLab, ONERA, Toulouse, France
  • 6Federal Institute of São Paulo (IFSP), São Paulo, Brazil
  • 7Institute of EnvironmentalAssessment and Water Research (IDAEA), CSIC, Barcelona, Spain

Abstract. The Sierra Nevada Lidar aerOsol Profiling Experiment I and II (SLOPE I and II) campaigns were intended to determine the vertical structure of the aerosol by remote sensing instruments and test the various retrieval schemes for obtaining aerosol microphysical and optical properties with in-situ measurements. These campaigns deployed a set of in-situ and remote sensing instruments at the stations include in AGORA observatory (Andalusian Global ObseRvatory of the Atmosphere) in the Granada area (Spain) along summer in 2016 and 2017. In this work, using the in-situ measurements performed at a high-altitude station, Sierra Nevada station, and airborne flights, we evaluate the retrievals of aerosol properties by GRASP code (Generalized Retrieval of Atmosphere and Surface Properties) combining lidar and sun-sky photometer measurements. Besides, we show an overview of aerosol properties retrieved by GRASP during SLOPE I and II campaigns. We evaluate the GRASP retrievals of total aerosol volume concentration (discerning between fine and coarse modes), extinction and scattering coefficients, and for the first time we present an evaluation of absorption coefficient.

The statistical analysis of the aerosol optical and microphysical properties, both column-integrated and vertically-resolved, from May to July 2016 and 2017 shows a large variability in aerosol load and types. The results show a strong predominance of desert dust particles due to the North African intrusions. The vertically-resolved analysis denotes a decay of the atmospheric aerosols with altitude up to 5 km a.s.l. Finally, two events of desert dust and biomass burning were used to show the high potential of GRASP to retrieve and study the aerosol properties profiles such as absorption coefficient and single scattering albedo for different aerosol types. The aerosol properties retrieved by GRASP show good agreement with simultaneous in situ measurements performed at Sierra Nevada Station (SNS) in Granada. In general, GRASP overestimates the in situ data at SNS with a mean difference lower than 6 µm3/cm3 for volume concentration, 11 Mm−1 and 2 Mm−1 for scattering and absorption coefficient. On the other hand, the comparison of GRASP with airborne measurements also shows an overestimation with mean absolute differences of 14 ± 10 Mm−1 and 1.2 ± 1.2 Mm−1 for scattering and absorption coefficients, showing a better agreement for absorption (scattering) coefficient with higher (lower) aerosol optical depth. The potentiality of GRASP showed in this study will contribute to enhancing the representativeness of the aerosol vertical distribution and provide information for satellite and global model evaluation.

Jose Antonio Benavent-Oltra et al.

Status: open (until 02 Apr 2021)

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Jose Antonio Benavent-Oltra et al.

Jose Antonio Benavent-Oltra et al.


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Short summary
In this paper, we use the GRASP algorithm combining different remote sensing measurements to obtain the aerosol vertical and column properties during SLOPE I and II campaings. We show an overview of aerosol properties retrieved by GRASP during these campaigns and evaluate the retrievals of aerosol properties using the in-situ measurements performed at a high-altitude station and airborne flights. For the first time we present an evaluation of absorption coefficient by GRASP.