Preprints
https://doi.org/10.5194/egusphere-2024-2400
https://doi.org/10.5194/egusphere-2024-2400
08 Oct 2024
 | 08 Oct 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Stratospheric residence time and the lifetime of volcanic stratospheric aerosols

Matthew Toohey, Yue Jia, Sujan Khanal, and Susann Tegtmeier

Abstract. The amount of time that volcanic aerosols spend in the stratosphere is one of the primary factors influencing the climate impact of volcanic eruptions. Stratospheric aerosol persistence has been described in different ways, with many works quoting an approximately 12 month “residence time” for aerosol from large tropical eruptions. Here, we aim to develop a framework for describing the evolution of global stratospheric aerosol after major volcanic eruptions and quantifying its persistence, based on global satellite-based aerosol observations, tracer transport simulations and simple conceptual modeling. We show that the stratospheric residence time of air, which is estimated through passive tracer pulse experiments and is one factor influencing the lifetime of stratospheric aerosols, is strongly dependent on the injection latitude and height, with an especially strong sensitivity to injection height in the first four kilometers above the tropical tropopause. Simulated stratospheric tracer evolution is best described by a simple model which includes a lag between the injection and initiation of removal from the stratosphere. Based on analysis of global stratospheric aerosol observations, we show that the stratospheric lifetime of stratospheric aerosol from the 1991 Pinatubo eruption is approximately 22 months. We estimate the potential impact of observational uncertainties on this lifetime finding it unlikely the lifetime of Pinatubo aerosol is less than 18 months.

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Matthew Toohey, Yue Jia, Sujan Khanal, and Susann Tegtmeier

Status: open (until 19 Nov 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2400', Daniele Visioni, 31 Oct 2024 reply
Matthew Toohey, Yue Jia, Sujan Khanal, and Susann Tegtmeier
Matthew Toohey, Yue Jia, Sujan Khanal, and Susann Tegtmeier

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Short summary
The climate impact of volcanic eruptions depends in part on how long aerosols spend in the stratosphere. We develop a conceptual model for stratospheric aerosol lifetime in terms of production and decay timescales, as well as a lag between injection and decay. We find residence time depends strongly on injection height in the lower stratosphere. We show that the lifetime of stratospheric aerosol from the 1991 Pinatubo eruption is around 22 months, significantly longer than commonly reported.