Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

Thomason, L. W.; Kovilakam, Mahesh; Schmidt, Anja; Savigny, Christian von; Knepp, T. N.; Rieger, Landon

doi:10.5194/acp-21-1143-2021

Cited by 23 publications

(39 citation statements)

References 53 publications

(55 reference statements)

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“…This coincidence presented both a scientific opportunity and measurement challenges. Raikoke injected SO 2 and ash to a peak altitude of ≈ 15 km (Thomason et al, 2021) with SO 2 detected shortly thereafter at 19 km (Hedelt et al, 2019). This resulted in an SO 2 column density in excess of 900 Dobson units (Hedelt et al, 2019) and an overall mass load of ≈ 1.5 Tg (Muser et al, 2020;de Leeuw et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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

et al. 2022

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“…Recently, it is shown that many small to moderate eruptions can manifest themselves during SAGE II and III/ISS data record (Thomason et al, 2021). The size information inferred from 525 to 1020 nm extinction ratios show that a decrease in extinction ratio (increase in aerosol size) following large volcanic eruptions, whereas for small to moderate eruptions, extinction ratios are apparently slightly higher (smaller aerosol size) (Thomason et al, 2021). Therefore, we note that inferring aerosol size information for the post-SAGE II period (September 2005 through May 2017) is deficient, particularly following several small to moderate volcanic eruptions.…”

Section: Comparison Of Sage Iii/iss Data With Osirismentioning

confidence: 99%

SAGE III/ISS aerosol/cloud categorization and its impact on GloSSAC

Kovilakam

Thomason

Knepp

2022

Preprint

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Abstract. The Stratospheric Aerosol and Gas Experiment on the International Space Station (SAGE III/ISS) began its mission in June 2017. SAGE III/ISS is an updated version of the SAGE III on Meteor (SAGE III/M3M) instrument that makes observations of stratospheric aerosol extinction coefficient at wavelengths that range from 385 to 1550 nm with a near global coverage between 60° S and 60° N. While SAGE III/ISS makes reliable and robust solar occultation measurements in stratosphere, similar to its predecessors, interpreting aerosol extinction measurements in the vicinity of tropopause and in the troposphere have been a challenge for all SAGE instruments. Herein, we discuss some of the challenges associated with discriminating between aerosols and clouds within the extinction measurements and describe the methods implemented to categorize clouds and aerosols using available SAGE III/ISS aerosol measurements. This cloud/aerosol categorization method is based on the results of Thomason and Vernier (2013) with some modifications that now incorporate the influence of recent volcanic/PyroCb events and a new method of locating aerosol centroid based on k-medoid clustering. We use version 5.2 of SAGE III/ISS extinction coefficients for the analysis. The current algorithm now classifies standard (background) and non-standard (enhanced) aerosols in the stratosphere and identify enhanced aerosols and aerosol/cloud mixture in the tropopause region. SAGE data is an important dataset in the GloSSAC data base and therefore, the impact of cloud-filtered aerosol extinction coefficient measurements on the latest version of GloSSAC (version 2.2) is also discussed.

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“…In addition, the variation of the stratospheric aerosol PSD after volcanic eruptions is not fully understood and a topic of current research. In a recent study, Thomason et al (2021) showed first evidence that the mean aerosol particle size decreases after many moderate volcanic eruptions. Since the eruption of Mt.…”

Section: Dependence On Particle Sizementioning

confidence: 99%

Is it possible to estimate aerosol optical depth from historic colour paintings?

Savigny

Lange

Hemkendreis

et al. 2022

Preprint

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Abstract. The idea of estimating stratospheric aerosol optical thickness from the twilight colours in historic paintings – particularly under conditions of volcanically enhanced stratospheric aerosol loading – is very tantalising, because it would provide information on the stratospheric aerosol loading over a period of several centuries. This idea has in fact been applied in a few studies in order to provide quantitative estimates of the aerosol optical depth after some of the major volcanic eruptions that occurred during the past 500 years. In this study we critically review this approach and come to the conclusion that the uncertainties of the estimated aerosol optical depths are so large that the values have to be considered highly questionable. We show that several auxiliary parameters – which are typically poorly known for historic eruptions – can have a similar effect on the red-green colour ratio as a change in optical depth typically associated with eruptions such as, e.g. Tambora in 1815 or Krakatao in 1883. Among the effects considered here, uncertainties in the aerosol particle size distribution have the largest impact on the colour ratios and hence the aerosol optical depth estimate. For solar zenith angles exceeding 80 degrees, uncertainties in the stratospheric ozone amount can also have a significant impact on the colour ratios. In addition, for solar zenith angles exceeding 90 degrees the colour ratios exhibit a dramatic dependence on solar zenith angle, rendering the estimation of aerosol optical depth essentially impossible.

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Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

Cited by 23 publications

References 53 publications

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

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

SAGE III/ISS aerosol/cloud categorization and its impact on GloSSAC

Is it possible to estimate aerosol optical depth from historic colour paintings?

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