Decadal Disruption of the QBO by Tropical Volcanic Supereruptions

Hans Brenna,Steffen Kutterolf,Claudia Timmreck,Ulrike Niemeier,Michael J Mills,Kirstin Krüger

doi:10.1029/2020gl089687

Abstract

AbstractThe Los Chocoyos (14.6°N, 91.2°W) supereruption happened ∼75,000 years ago in Guatemala and was one of the largest eruptions of the past 100,000 years. It emitted enormous amounts of sulfur, chlorine, and bromine, with multi‐decadal consequences for the global climate and environment. Here, we simulate the impact of a Los Chocoyos‐like eruption on the quasi‐biennial oscillation (QBO), an oscillation of zonal winds in the tropical stratosphere, with a comprehensive aerosol chemistry Earth System Model. We find a ∼10‐year disruption of the QBO starting 4 months post eruption, with anomalous easterly winds lasting ∼5 years, followed by westerlies, before returning to QBO conditions with a slightly prolonged periodicity. Volcanic aerosol heating and ozone depletion cooling leads to the QBO disruption and anomalous wind regimes through radiative changes and wave‐mean flow interactions. Different model ensembles, volcanic forcing scenarios and results of a second model back up the robustness of our results.

Highlights

Supereruptions are some of the most violent natural events on Earth
The modeled quasi-biennial oscillation (QBO) winds are in thermal wind balance with the tropical temperature field, as shown by the wind shear
We see that the alternating patterns of easterly and westerly zonal wind shears align with the alternating patterns of positive and negative monthly mean temperature anomalies (Figures 1a and 1b; all anomalies are with respect to the monthly climatology)

Summary

Introduction

Los Chocoyos (14.6°N, 91.2°W) erupted 74,800 ± 1,800 years ago (Cisneros de León et al, 2021) in Guatemala forming the current Atitlán caldera, and was one of the largest volcanic events of the past 100,000 years with a magnitude M = 8 (calculated after Pyle (2013)). It released massive amounts of sulfur, chlorine, and bromine to the atmosphere (Kutterolf et al, 2016 and reference therein). The efficient injection of volcanic volatiles thereby modifies the thermal structure of the stratosphere, which impacts large-scale dynamics (Bittner et al, 2016; Brenna et al, 2019; Stenchikov et al, 2002; Toohey et al, 2014).

Methods

Results

Conclusion