Abstract
Abstract. We present retrievals of tropospheric and stratospheric height profiles of particle mass, volume, surface area, and number concentrations in the case of wildfire smoke layers as well as estimates of smoke-related cloud condensation nuclei (CCN) and ice-nucleating particle (INP) concentrations from backscatter lidar measurements on the ground and in space. Conversion factors used to convert the optical measurements into microphysical properties play a central role in the data analysis, in addition to estimates of the smoke extinction-to-backscatter ratios required to obtain smoke extinction coefficients. The set of needed conversion parameters for wildfire smoke is derived from AERONET observations of major smoke events, e.g., in western Canada in August 2017, California in September 2020, and southeastern Australia in January–February 2020 as well as from AERONET long-term observations of smoke in the Amazon region, southern Africa, and Southeast Asia. The new smoke analysis scheme is applied to CALIPSO observations of tropospheric smoke plumes over the United States in September 2020 and to ground-based lidar observation in Punta Arenas, in southern Chile, in aged Australian smoke layers in the stratosphere in January 2020. These case studies show the potential of spaceborne and ground-based lidars to document large-scale and long-lasting wildfire smoke events in detail and thus to provide valuable information for climate, cloud, and air chemistry modeling efforts performed to investigate the role of wildfire smoke in the atmospheric system.
Highlights
Record-breaking injections of Canadian and Australian wildfire smoke into the upper troposphere and lower stratosphere (UTLS) in 2017 and 2020 caused strong perturbations of stratospheric aerosol conditions in the Northern and Southern Hemisphere
To smoke particles acting as heterogeneous ice-nucleating particle (INP), we need to consider full deliquescence of smoke particles so that homogeneous freezing comes into play
We presented a new method that permits the retrieval of tropospheric and stratospheric height profiles of smoke particle mass, volume, surface area, and number concentrations as well as first-order estimates of cloud condensation nuclei (CCN) and INP concentrations from single-wavelength backscatter lidar observations
Summary
Record-breaking injections of Canadian and Australian wildfire smoke into the upper troposphere and lower stratosphere (UTLS) in 2017 and 2020 caused strong perturbations of stratospheric aerosol conditions in the Northern and Southern Hemisphere. For volcanic aerosol a conversion technique was introduced to derive climate and air-chemistry-relevant parameters such as particle extinction coefficient and related aerosol optical thickness (AOT), mass, and surface area concentration from the backscatter lidar observations (Jäger and Hofmann, 1991; Jäger et al, 1995; Jäger and Deshler, 2002, 2003) Such a conversion scheme is needed for the analysis of free-tropospheric and stratospheric wildfire smoke layers but is not available yet.
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