Variability of the Aerosol Content in the Tropical Lower Stratosphere from 2013 to 2019: Evidence of Volcanic Eruption Impacts

Abstract

This paper quantifies the tropical stratospheric aerosol content as impacted by volcanic events over the 2013–2019 period. We use global model simulations by the Whole Atmosphere Community Climate Model (WACCM) which is part of the Community Earth System Model version 1.0 (CESM1). WACCM is associated with the Community Aerosol and Radiation Model for Atmospheres (CARMA) sectional aerosol microphysics model which includes full sulphur chemical and microphysical cycles with no a priori assumption on particle size. Five main volcanic events (Kelud, Calbuco, Ambae, Raikoke and Ulawun) have been reported and are shown to have significantly influenced the stratospheric aerosol layer in the tropics, either through direct injection in this region or through transport from extra-tropical latitudes. Space-borne data as well as ground-based lidar and balloon-borne in situ observations are used to evaluate the model calculations in terms of aerosol content, vertical distribution, optical and microphysical properties, transport and residence time of the various volcanic plumes. Overall, zonal mean model results reproduce the occurrence and vertical extents of the plumes derived from satellite observations but shows some discrepancies for absolute values of extinction and of stratospheric aerosol optical depth (SAOD). Features of meridional transport of the plumes emitted from extra-tropical latitudes are captured by the model but simulated absolute values of SAOD differ from 6 to 200% among the various eruptions. Simulations tend to agree well with observed in situ vertical profiles for the Kelud and Calbuco plumes but this is likely to depend on the period for which comparison is done. Some explanations for the model–measurement discrepancies are discussed such as the inaccurate knowledge of the injection parameters and the presence of ash not accounted in the simulations.

Tracking the 2022 Hunga Tonga‐Hunga Ha'apai Aerosol Cloud in the Upper and Middle Stratosphere Using Space‐Based Observations

“…This paper focuses on observations by NASA's OMPS LP instrument, which has previously made observations of smaller eruptions including Kelut (2014), Calbuco (2015), Ambae (2018), Ulawun (2019) and Raikoke (2019) (Gorkavyi et al., 2021 ; Kloss et al., 2020 , 2021 ; Tadiga et al., 2022 ). Due to the unusual strength of the eruption, aerosol is observed at altitudes that far exceed the normalization altitude for the standard OMPS LP aerosol retrieval algorithm (above which aerosol scattering is assumed to be negligible).…”

Stratospheric Aerosol Characteristics from the 2017–2019 Volcanic Eruptions Using the SAGE III/ISS Observations

“…Volcanic eruptions are unpredictable episodic events that can have significant impacts on the global climate by altering the stratospheric composition, vertical temperature profiles, radiative processes, large-scale circulation, transport, and surface weather [1][2][3][4][5][6][7][8][9]. Although large magnitude eruptions with a volcanic explosivity index (VEI) equal to or greater than 5 (also known as Plinian eruptions), injecting around 10 Tg of sulfur dioxide (SO 2 ), are rare on a decadal scale, they have a profound impact on the key modes of climate variability [10,11].…”

Case Study of a Mesospheric Temperature Inversion over Maïdo Observatory through a Multi-Instrumental Observation

“…The Atmospheric Research Whole Atmosphere Community Climate Model version 4 (WACCM4, https://www2.acom.ucar.edu/gcm/waccm, accessed on 11 April 2023) is a comprehensive GCM spanning the height range from the earth's surface up to 150 km in the thermosphere and a key component of the National Center for Atmospheric Research (NCAR) Community Earth System Model version 1.0 (CESM1). The setups of the simulations used in our study are described in [54] with horizontal resolutions of 2.5 • × 1.9 • (144 × 96 grids) and 88 vertical levels included a nudging towards the Modern-Era Retrospective analysis for Research and Application version 2 (MERRA2) at a time step of 30 min. Dynamic output fields of temperature, horizontal wind and geopotential heights have a vertical resolution of <1.2 km in the troposphere and the lower stratosphere, between 1.2 km and 2 km up to 67 km height in the mesosphere and ~3 km in the lower thermosphere.…”