Evaluation of a method for converting Stratospheric Aerosol and Gas Experiment (SAGE) extinction coefficients to backscatter coefficients for intercomparison with lidar observations

Knepp, T. N.; Thomason, L. W.; Roell, Marilee; Damadeo, Robert; Leavor, Kevin; Leblanc, Thierry; Chouza, Fernando; Khaykin, Sergey; Godin‐Beekmann, Sophie; Flittner, D. E.

doi:10.5194/amt-13-4261-2020

Cited by 4 publications

(3 citation statements)

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“…Initially, the background statistics were calculated using only the month prior to each event, but that provided in-sufficient sampling for the Ambae and Ulawun events due to SAGE's observation schedule (see, for example, Fig. 1 of Knepp et al, 2020). Therefore, the background time period for the Ambae and Ulawun events was expanded to include 9 months prior to the eruption.…”

Section: Detection and Classification Methodsmentioning

confidence: 99%

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Identification of smoke and sulfuric acid aerosol in SAGE III/ISS extinction spectra

et al. 2022

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We developed a technique to classify the composition of enhanced aerosol layers as either smoke or sulfuric acid aerosol using extinction spectra from the Stratospheric Aerosol and Gas Experiment III instrument aboard the International Space Station (SAGE III/ISS). This method takes advantage of the different spectral properties of smoke and sulfuric acid aerosol, which is manifest in distinctly different spectral slopes in the SAGE III/ISS data. Herein we demonstrate the utility of this method and present an evaluation of its performance using four case-study events of two moderate volcanic eruptions (2018 Ambae eruption and 2019 Ulawun eruption, both of which released <0.5 Tg of SO 2 ) and two large wildfire events (2017 Canadian pyroCb and 2020 Australian pyroCb). We provide corroborative data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument to support these classifications. This method correctly classified smoke and sulfuric acid plumes in the case-study events >81 % and >99.5 % of the time, respectively. The application of this method to a large volcanic event (i.e., the 2019 Raikoke eruption; ≥ 1.5 Tg SO 2 ) serves as an example of why this method is limited to small and moderate volcanic events as it incorrectly classified Raikoke's larger sulfuric acid particles as smoke. We evaluated the possibility of smoke being present in the stratosphere before and after the Raikoke eruption. While smoke was present during this time period it was insufficient to account for the magnitude of smoke classifications we observed. Therefore, while this method worked well for largescale wildfire events and eruptions that inject less SO 2 , the size of the aerosol created by the Raikoke eruption was outside the applicable range of this method.

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Section: Detection and Classification Methodsmentioning

confidence: 99%

“…In addition to the spectrograph there is an InGaAs photodiode at 1550 nm. The ISS orbit is inclined at 51.6 • , resulting in more observations at midlatitudes than at tropical latitudes as shown by Knepp et al (2020).…”

Section: Sage III Instrument and Data Preparationmentioning

confidence: 99%

Identification of smoke and sulfuric acid aerosol in SAGE III/ISS extinction spectra

et al. 2022

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“…The Stratospheric Aerosol and Gas Experiment III (SAGE III) is a NASA instrument, built as part of the Earth Observing System program, installed on the International Space Station (SAGE III‐ISS, Cisewski et al., 2014; Knepp et al., 2020). The instrument is a spectrometer that measures near‐UV, visible, and near‐Infrared (IR) radiation through the Earth's limb during solar and lunar occultations and limb scattering (during the daytime side of the orbit).…”

Section: Datamentioning

confidence: 99%