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Radiative and Chemical Response to Interactive Stratospheric Sulfate Aerosols in Fully Coupled CESM1(WACCM)
Author(s) -
Mills Michael J.,
Richter Jadwiga H.,
Tilmes Simone,
Kravitz Ben,
MacMartin Douglas G.,
Glanville Anne A.,
Tribbia Joseph J.,
Lamarque JeanFrançois,
Vitt Francis,
Schmidt Anja,
Gettelman Andrew,
Hannay Cecile,
Bacmeister Julio T.,
Kinnison Douglas E.
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd027006
Subject(s) - sulfate aerosol , aerosol , stratosphere , atmospheric sciences , ozone layer , climatology , environmental science , ozone depletion , atmosphere (unit) , climate model , ozone , radiative forcing , atmospheric chemistry , meteorology , climate change , geology , physics , oceanography
We present new insights into the evolution and interactions of stratospheric aerosol using an updated version of the Whole Atmosphere Community Climate Model (WACCM). Improved horizontal resolution, dynamics, and chemistry now produce an internally generated quasi‐biennial oscillation and significant improvements to stratospheric temperatures and ozone compared to observations. We present a validation of WACCM column ozone and climate calculations against observations. The prognostic treatment of stratospheric sulfate aerosols accurately represents the evolution of stratospheric aerosol optical depth and perturbations to solar and longwave radiation following the June 1991 eruption of Mount Pinatubo. We confirm the inclusion of interactive OH chemistry as an important factor in the formation and initial distribution of aerosol following large inputs of sulfur dioxide (SO 2 ) to the stratosphere. We calculate that depletion of OH levels within the dense SO 2 cloud in the first weeks following the Pinatubo eruption significantly prolonged the average initial e ‐folding decay time for SO 2 oxidation to 47 days. Previous observational and model studies showing a 30 day decay time have not accounted for the large (30–55%) losses of SO 2 on ash and ice within 7–9 days posteruption and have not correctly accounted for OH depletion. We examine the variability of aerosol evolution in free‐running climate simulations due to meteorology, with comparison to simulations nudged with specified dynamics. We assess calculated impacts of volcanic aerosols on ozone loss with comparisons to observations. The completeness of the chemistry, dynamics, and aerosol microphysics in WACCM qualify it for studies of stratospheric sulfate aerosol geoengineering.