Observing the Impact of Calbuco Volcanic Aerosols on South Polar Ozone Depletion in 2015

Abstract

The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April and a record‐large Antarctic ozone hole in October and November. Here we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observations and an Earth system model. We analyze ozonesondes, as well as data from the Microwave Limb Sounder. We employ the Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model (WACCM) in a specified dynamics setup, which includes calculations of volcanic effects. The Cloud‐Aerosol Lidar with Orthogonal Polarization data indicate enhanced volcanic liquid sulfate 532 nm backscatter values as far poleward as 68°S during October and November (in broad agreement with WACCM). Comparison of the location of the enhanced aerosols to ozone data supports the view that aerosols played a major role in increasing the ozone hole size, especially at pressure levels between 150 and 100 hPa. Ozonesonde vertical ozone profiles from the sites of Syowa, South Pole, and Neumayer display the lowest individual October or November measurements at 150 hPa since the 1991 Mount Pinatubo eruption period, with Davis showing similarly low values, but no available 1990 data. The analysis suggests that under the cold conditions ideal for ozone depletion, stratospheric volcanic aerosol particles from the moderate‐magnitude eruption of Calbuco in 2015 greatly enhanced austral ozone depletion, particularly at 55–68°S, where liquid binary sulfate aerosols have a large influence on ozone concentrations.

Stratospheric Aerosols, Polar Stratospheric Clouds, and Polar Ozone Depletion After the Mount Calbuco Eruption in 2015

“…This result is consistent with the location of the volcanic sulfuric acid aerosol layers around 16 km shown in CALIPSO and modeled backscatter figures (Figures ). This result is also consistent with Stone et al (), who found the volcanic aerosol enhances the ozone depletion particularly at 150–100 hPa and 55–68°S. Sunlight first causes ozone depletion near the edge of the vortex.…”

“…In the remaining discussion, we will refer to this version of the model as Solomon et al (). Stone et al () found the simulated backscatter of the volcanic sulfate aerosol was consistent with the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations(CALIPSO) and found enhanced ozone depletion particularly at 150–100 hPa and 55–68°S. Ivy et al () found the enhanced ozone depletion was mostly caused by the volcanic aerosol, while the effect of dynamic or thermal feedbacks on ozone was minimal.…”

“…How do the sulfate aerosol evolve with time and enter the Antarctic polar vortex? How does the simulated evolution of gas phase HNO 3 near the South Pole compare with the Microwave Limb Sounder (MLS) observations? Do volcanic sulfuric acid aerosol and perturbed PSCs enhance ozone depletion and expand the area of the ozone hole as found by Solomon et al ()? How do our sectional simulations of surface area density (SAD) compare with simulations using a modal aerosol model by Solomon et al (), Stone et al (), and Ivy et al ()?…”

“…Satellite observations (discussed in section ) show the volcanic sulfate aerosol extended past the tip of South America, and remained abundant in October of 2015 when the ozone hole typically forms. Stone et al () and Ivy et al () conducted detailed analyses of ozone depletion after the 2015 Mount Calbuco eruption. These studies used the Chemistry Climate Model Initiative (CCMI) version of the Community Earth System Model version 1 (CESM1) Whole Atmosphere Community Climate Model (WACCM).…”

A Multiwavelength Retrieval Approach for Improved OSIRIS Aerosol Extinction Retrievals

“…Although OCS is the primary driver of the stratospheric aerosol during background periods (Sheng et al, ), even moderate volcanic eruptions, typically with a volcanic explosive index of three or four, can have a profound impact on aerosol levels (Vernier et al, ). The last two decades have been punctuated by several of these small‐to‐moderate eruptions and they have an important impact on climate, both through ozone depletion (Stone et al, ) and contributions to the radiative forcing (Solomon et al, ; Fyfe et al, ). The importance, as well as variability of the aerosol layer has meant that continuing measurements are of high importance for understanding the larger climate system.…”