A near-global multiyear climate data record of the fine-mode and coarse-mode components of atmospheric pure-dust
Abstract. A new four-dimensional, multiyear, and near-global climate data record of the fine-mode (submicrometer in terms of diameter) and coarse-mode (supermicrometer in terms of diameter) components of atmospheric pure-dust, is presented. The separation of the two modes of dust in detected atmospheric dust layers is based on a combination of (1) the total pure-dust product provided by the well-established European Space Agency (ESA) – “LIdar climatology of Vertical Aerosol Structure” (LIVAS) database and (2) the coarse-mode component of pure-dust provided by the first-step of the two-step POlarization LIdar PHOtometer Networking (POLIPHON) technique, developed in the framework of European Aerosol Research Lidar Network (EARLINET). Accordingly, the fine-mode component of pure-dust is extracted as the residual between the LIVAS total pure-dust and the coarse-mode component of pure-dust. Intermediate steps involve the implementation of regionally-dependent lidar-derived lidar-ratio values and AErosol RObotic NETwork (AERONET) based climatological extinction-to-volume conversion factors, facilitating conversion of dust backscatter into extinction and subsequently extinction into mass concentration. The decoupling scheme is applied to Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) observations at 532 nm. The final products consist of the fine-mode and coarse-mode of atmospheric pure-dust, of quality-assured profiles of backscatter coefficient at 532 nm, extinction coefficient at 532 nm, and mass concentration for each of the two components. The datasets are established primarily with the original L2 horizontal (5 km) and vertical (60 m) resolution of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) along the CALIPSO orbit-path, and secondly in averaged profiles of seasonal-temporal resolution, 1°×1° spatial resolution, and with the original vertical resolution of CALIPSO, focusing on the latitudinal band extending between 70° S and 70° N and covering more than 15-years of Earth Observation (06/2006–12/2021). The quality of the dust products is justified by using AERONET fine-mode and coarse-mode aerosol optical thickness (AOT) interpolated to 532 nm and AERosol properties – Dust (AER-D) campaign airborne in-situ particle size distributions (PSDs) as reference datasets, during atmospheric conditions characterized by dust presence. The near-global fine-mode and coarse-mode pure-dust climate data record is considered unique with respect to a wide range of potential applications, including climatological, time-series, and trend analysis over extensive geographical domains and temporal periods, validation of atmospheric dust models and reanalysis datasets, assimilation activities, and investigation of the role of airborne dust on radiation and air quality.
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