Smoke of extreme Australian bushfires observed in the stratosphere over Punta Arenas, Chile, in January 2020: optical thickness, lidar ratios, and depolarization ratios at 355 and 532 nm

Abstract

<jats:p>Abstract. We present particle optical properties of stratospheric smoke layers observed over Punta Arenas (53.2° S, 70.9° W), Chile, at the southernmost tip of South America in January 2020. The smoke originated from the record-breaking bushfires in Australia. The stratospheric aerosol optical thickness reached values up to 0.7 at 532 nm in mid January 2020. The measured smoke extinction-to-backscatter ratios (lidar ratios) and linear depolarization ratios at 355 and 532 nm wavelength indicate shape, size, and light-absorption properties and are important input parameters in the analysis of spaceborne lidar observations of the CALIPSO and Aeolus missions. They are also of key importance regarding the homogenization of the overall Aeolus (355 nm wavelength) and CALIPSO (532 nm wavelength) smoke data sets and interpretation of the observations with respect to the spread of the smoke particles across the southern hemisphere and decay of the stratospheric perturbation. We found typical values and spectral dependencies of the lidar ratio and linear depolarization ratio for aged stratospheric smoke. At 355 nm, the lidar ratio and depolarization ratio ranged from 53–97 sr and 0.2–0.26, respectively. At 532 nm, the lidar ratios were higher (76–104 sr) and the depolarization ratios were lower with values around 0.15. The found lidar ratio and depolarization ratio values for Australian smoke are in good agreement with respective ones obtained from observations of stratospheric smoke layers over central Europe originating from the record-breaking Canadian wildfires in the summer of 2017. The higher 532 nm lidar ratios, however, indicate stronger absorption by the Australian smoke particles. </jats:p>

Californian Wildfire Smoke Over Europe: A First Example of the Aerosol Observing Capabilities of Aeolus Compared to Ground‐Based Lidar

“…Within this pronounced aerosol layer, the agreement between the lidar ratio observed by the ground‐based lidar (and converted to the co‐polar (Aeolus‐like) component) and the one observed by Aeolus is reasonable (please remind, that current Aeolus uncertainties are overestimated and thus unrealistically high). The PollyXT observations yield a lidar ratio of the smoke of about 40–50 sr at 355 nm, which is in excellent agreement with former observations of long‐range transported smoke (Haarig et al., 2018; Ohneiser et al., 2020). Aeolus measured values within the same range, even though some outliers in the smoke region exist (at around 6 km).…”

2019‒2020 Australian bushfire air particulate pollution and impact on the South Pacific Ocean

“…2 , 3 , 4 ) revealed an impact concentrated primarily in the South Pacific marginal seas due to the dominance of coarse mineral dust particles and the potentially faster settling rate 33 , 34 . The fine smoke particles had a longer and more widespread influence, even across the South Pacific Ocean; this was consistent with the detailed backward trajectory analysis and TROPOMI observations 35 , 36 . According to the ΔUVAI in Fig.…”

“…The use of passive remote sensing for the high spatio-temporal resolution detection of atmospheric aerosol components and trace element monitoring for air pollution also presents limitations. In future work, the use of satellite-based lidar will facilitate the study and monitoring of atmospheric aerosol particle types and trace element pollution with high resolution and quality 35 , 41 .…”

Quantifying the Source Term and Uniqueness of the August 12, 2017 Pacific Northwest PyroCb Event

“…A pyroCb event occurring post‐PNE in southeast Australia at the dawn of 2020, fewer than three years after the PNE, has garnered great interest and attention. The so‐called Australia New Year (ANY) (Kablick et al., 2020) pyroCb event of December 2019–January 2020 resulted in an unprecedented stratospheric plume with respect to diabatic ascent, gaseous constituent anomalies, and even regional smoke‐induced circulation (Allen et al., 2020; Boone et al., 2020; Kablick et al., 2020; Khaykin et al., 2020; Ohneiser et al., 2020). Figure 1 illustrates that the ANY stratospheric smoke plume exceeded all historical AAI anomalies except for PNE, suggesting an especially notable pyroCb event.…”