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UP: Fachverband Umweltphysik

UP 2: Clouds and Aerosols

UP 2.7: Vortrag

Donnerstag, 2. September 2021, 15:40–15:55, H3

Satellite observations of volcanic eruptions leading to smaller average stratospheric aerosol sizes — •Felix Wrana¹, Christian von Savigny¹, and Larry W. Thomason² — ¹Institut für Physik, Universität Greifswald, Greifswald, Germany — ²NASA Langley Research Center, Hampton, Virginia, USA

We present surprising results of our stratospheric aerosol size retrieval which is using the SAGE III/ISS solar occultation measurements, that started in 2017. Due to the broad wavelength spectrum covered by the instrument a robust and simultaneous retrieval of the median radius and mode width of monomodal lognormal size distributions is possible. We focus on three small to mid-intensity volcanic eruptions that were observed by SAGE III/ISS and that reached and perturbed the stratospheric aerosol layer: The Ambae eruptions (15.3°S) in spring of 2018 and the Raikoke (48.3°N) and Ulawun (5.05°S) eruptions, both in June 2019. While the Raikoke eruption led to an increase in the median radius of the stratospheric aerosols, which was to be expected and is in line with previous observations, the Ambae and Ulawun eruption had the opposite effect. After both eruptions the average aerosol size decreased, with lower median radii and narrower size distributions, while the number density increased strongly. The observation that volcanic eruptions may lead to smaller average stratospheric aerosol sizes, as also recently discussed by Thomason et al. (2021), is a novel one and should be of great interest to the modeling as well as remote sensing community. In our talk, we will present the temporal and spatial evolution of the size distribution parameters.