The effects of volcanic aerosols on mid-latitude ozone recovery

Abstract

In this paper, comparisons between the derived Chemistry Climate Model Initiative aerosol data set to balloon sonde measurements of aerosols made in Laramie, Wyoming are made between 1979- 2012. Using the derived CCMI aerosol data set as the input for surface area density of aerosols in the Specified Dynamics-Whole Atmosphere Climate Community Model (SD-WACCM), the impacts of volcanic aerosols on mid-latitude ozone loss are investigated. These results are compared to the ozone column expected recovery from a run of SD-WACCM with no volcanic eruptions in the same period. Particular emphasis is placed on the last decade to investigate how the small volcanic eruptions that have characterized the period of 2008-2012 have impacted the ozone column recovery during this time at northern mid-latitudes as atmospheric chlorine levels decrease from regulation. It is found that the CCMI aerosol data set underestimates aerosol surface area density between the local tropopause and approximately 70mbar in the lower stratosphere. This underestimation is corrected and the resulting change in the ozone column is compared to the initial model output with no volcanic aerosols. Using the correct aerosol values, it is shown that ozone loss in the lower stratosphere after these small, recent volcanoes rivals that of the post-Pinatubo years around 1995-1996.