Statistical validation of Aeolus L2A particle backscatter coefficient retrievals over ACTRIS/EARLINET stations on the Iberian Peninsula

The Global Observing System (GOS) has encountered some limitations due to a lack of worldwide real-time wind measurements. In this context, the European Space Agency (ESA) has developed the Aeolus satellite mission, based on the ALADIN (Atmospheric Laser Doppler Instrument) Doppler wind lidar; this...

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Published in:Atmospheric chemistry and physics 2022-01, Vol.22 (2), p.1425-1451
Main Authors: Abril-Gago, Jesús, Guerrero-Rascado, Juan Luis, Costa, Maria João, Bravo-Aranda, Juan Antonio, Sicard, Michaël, Bermejo-Pantaleón, Diego, Bortoli, Daniele, Granados-Muñoz, María José, Rodríguez-Gómez, Alejandro, Muñoz-Porcar, Constantino, Comerón, Adolfo, Ortiz-Amezcua, Pablo, Salgueiro, Vanda, Jiménez-Martín, Marta María, Alados-Arboledas, Lucas
Format: Article
Language:English
Subjects:
Aerosol layers
Aerosol optical properties
Aerosol research
Aerosols
Algorithms
Anthropogenic factors
Atmosphere
Atmospheric aerosols
Atmospheric lasers
Atmospheric particulates
Backscatter
Backscattering
Climate change
Clouds
Coefficients
Depolarization
Doppler sonar
Dust storms
Gases
Intercomparison
Lasers
Lidar
Optical properties
Optical radar
Radiation
Real time
Remote sensing
Satellites
Statistical analysis
Statistical methods
Statistics
Stratosphere
Time measurement
Trace gases
Troposphere
Wind measurement
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Summary:The Global Observing System (GOS) has encountered some limitations due to a lack of worldwide real-time wind measurements. In this context, the European Space Agency (ESA) has developed the Aeolus satellite mission, based on the ALADIN (Atmospheric Laser Doppler Instrument) Doppler wind lidar; this mission aims to obtain near-real-time wind retrievals at the global scale. As spin-off products, the instrument retrieves aerosol optical properties such as particle backscatter and extinction coefficients. In this work, a validation of Aeolus reprocessed (baseline 10) co-polar backscatter coefficients (βAeoluspart) is presented through an intercomparison with analogous ground-based measurements taken at the ACTRIS (Aerosols, Clouds and Trace gases Research InfraStructure Network)/EARLINET (European Aerosol Research Lidar Network) stations of Granada (Spain), Évora (Portugal) and Barcelona (Spain) over the period from July 2019 until October 2020. Case studies are first presented, followed by a statistical analysis. The stations are located in a hot spot between Africa and the rest of Europe, which guarantees a variety of aerosol types, from mineral dust layers to continental/anthropogenic aerosol, and allows us to test Aeolus performance under different scenarios. The so called Aeolus-like profiles (βAeoluslike,355part) are obtained from total particle backscatter coefficient and linear particle depolarization ratio (δlinearpart) profiles at 355 and 532 nm measured from the surface, through a thorough bibliographic review of dual-polarization measurements for relevant aerosol types. Finally, the study proposes a relation for the spectral conversion of δlinearpart, which is implemented in the Aeolus-like profile calculation. The statistical results show the ability of the satellite to detect and characterize significant aerosol layers under cloud-free conditions, along with the surface effect on the lowermost measurements, which causes the satellite to largely overestimate co-polar backscatter coefficients. Finally, the Aeolus standard correct algorithm middle bin (SCAmb) shows a better agreement with ground-based measurements than the standard correct algorithm (SCA), which tends to retrieve negative and meaningless coefficients in the clear troposphere. The implementation of Aeolus quality flags entails a vast reduction in the number of measurements available for comparison, which affects the statistical significance of the results.
ISSN:1680-7324
1680-7316
1680-7324
DOI:10.5194/acp-22-1425-2022