Abstract
The 2019 eruption of Raikoke was the largest volcanic eruption since 2011 and it was coincident with 2 major wildfires in the northern hemisphere. The impact of these events was manifest in the SAGE III/ISS extinction coefficient measurements. As the volcanic aerosol layers moved southward, a secondary peak emerged at an altitude higher than that which is expected for sulfuric acid aerosol. It was hypothesized that this secondary plume may contain a non-negligible amount of smoke contribution. We developed a technique to classify the composition of enhanced aerosol layers as either smoke or sulfuric acid aerosol. 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 using 4 case-study events (2018 Ambae eruption, 2019 Ulawun eruption, 2017 Canadian pyroCb, and 2020 Australian pyroCb) and provide corroborative data from the CALIOP instrument before applying it to the Raikoke plumes. We determined that, in the time period following the Raikoke eruption, smoke and sulfuric acid aerosol were present throughout the atmosphere and the 2 aerosol types were preferentially partitioned to higher (smoke) and lower (sulfuric acid) altitudes. Herein, we present an evaluation of the performance of this classification scheme within the context of the aforementioned case-study events followed by a brief discussion of this method's applicability to other events as well as its limitations.
Highlights
The 2019 eruption of Raikoke was the largest volcanic eruption since 2011 and it was coincident with 2 major wildfires in the northern hemisphere
As the volcanic aerosol layers moved southward, a secondary peak emerged at an altitude higher than that which is expected for sulfuric acid aerosol
We developed a technique to classify the composition of enhanced aerosol layers as either smoke or sulfuric acid aerosol
Summary
Located on the Kuril archipelago, Raikoke (48.3◦N, 153.3◦E) is a volcanic island that has a history of moderately-sized eruptions that have been recorded over the last 200 years (Tanakadate, 1925; Newhall and Self, 1982; Rashidov et al, 2019). Though the 75 extent of the climatological impacts have been called into question (D’Arrigo et al, 2011), the Laki eruptions serve as a prime example of how smaller eruptions can have significant impact on both life and climate Another source of stratospheric aerosol that has become significant over the past decade is large-scale, intense-burning, wildfire events that generate pyrocumulonimbus clouds (pyroCbs, referred to as cumulonimbus flammagenitus), which were originally hypothesized to only exist as a product of nuclear explosions (Turco et al, 1983). These fires burn with sufficient 80 intensity to form a cumulonimbus cloud and inject smoke and volatile organic compounds directly into the stratosphere (Fromm et al, 2006, 2010) on a scale comparable to a volcanic eruption of VEI-3–4 (Peterson et al, 2018). We discuss limitations of this methodology, namely that it is limited to moderately-sized eruptions (VEI ≤5) and large-scale pyroCb events as detailed below
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
