Title

Unexpected Repartitioning of Stratospheric Inorganic Chlorine After the 2020 Australian Wildfires

Authors

Susan E. Strahan, NASA Goddard Space Flight Center
Dan Smale, National Institute of Water and Atmospheric Research
Susan Solomon, Massachusetts Institute of Technology
Ghassan Taha, NASA Goddard Space Flight Center
Megan R. Damon, NASA Goddard Space Flight Center
Stephen D. Steenrod, NASA Goddard Space Flight Center
Nicholas Jones, University of Wollongong
Ben Liley, National Institute of Water and Atmospheric Research
Richard Querel, National Institute of Water and Atmospheric Research
John Robinson, National Institute of Water and Atmospheric Research

Publication Name

Geophysical Research Letters

Abstract

The inorganic chlorine (Cly) and odd nitrogen (NOy) chemical families influence stratospheric O3. In January 2020 Australian wildfires injected record-breaking amounts of smoke into the southern stratosphere. Within 1–2 months ground-based and satellite observations showed Cly and NOy were repartitioned. By May, lower stratospheric HCl columns declined by ∼30% and ClONO2 columns increased by 40%–50%. The Cly perturbations began and ended near the equinoxes, increased poleward, and peaked at the winter solstice. NO2 decreased from February to April, consistent with sulfate aerosol reactions, but returned to typical values by June - months before the Cly recovery. Transport tracers show that dynamics not chemistry explains most of the observed O3 decrease after April, with no significant transport earlier. Simulations assuming wildfire smoke behaves identically to sulfate aerosols couldn't reproduce observed Cly changes, suggesting they have different composition and chemistry. This undermines our ability to predict ozone in a changing climate.

Open Access Status

This publication is not available as open access

Volume

49

Issue

14

Article Number

e2022GL098290

Funding Number

1906719

Funding Sponsor

National Aeronautics and Space Administration