Aerosol Detection from the Cloud-Aerosol Transport System on the International Space Station: Algorithm Overview and Implications for Diurnal Sampling

Concentrations of particulate aerosols and their vertical placement in the atmosphere determine their interaction with the Earth system and their impact on air quality. Space-based lidar, such as the Cloud-Aerosol Transport System (CATS) technology demonstration instrument, is well-suited for determining the vertical structure of these aerosols and their diurnal cycle. Through the implementation of aerosol-typing algorithms, vertical layers of aerosols are assigned a type, such as marine, dust, and smoke, and a corresponding extinction-to-backscatter (lidar) ratio. With updates to the previous aerosol-typing algorithms, we find that CATS, even as a technology demonstration, observed the documented seasonal cycle of aerosols, comparing favorably with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) space-based lidar and the NASA Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) model reanalysis. By leveraging the unique orbit of the International Space Station, we find that CATS can additionally resolve the diurnal cycle of aerosol altitude as observed by ground-based instruments over the Maritime Continent of Southeast Asia.

Automated summary

The concentration and vertical distribution of particulate aerosols in the atmosphere have significant influence on their interaction with the Earth system and air quality. Utilizing space-based lidar technology, the Cloud-Aerosol Transport System (CATS) can accurately determine the vertical structure and diurnal cycle of these aerosols. By implementing aerosol-typing algorithms, CATS assigns different types and extinction-to-backscatter ratios to vertical layers of aerosols. With improved algorithms, CATS demonstrated comparable results to CALIOP lidar and MERRA-2 model reanalysis, capturing the seasonal cycle of aerosols. Leveraging the unique orbit of the International Space Station, CATS also successfully resolved the diurnal cycle of aerosol altitude in the Maritime Continent of Southeast Asia as observed by ground-based instruments.