Faster Tropical Upper Stratospheric Upwelling Drives Changes in Ozone Chemistry

Date

2022-10-25

Department

Program

Citation of Original Publication

Strahan, S. E., Coy, L., Douglass, A. R., & Damon, M. R. (2022). Faster tropical upper stratospheric upwelling drives changes in ozone chemistry. Geophysical Research Letters, 49, e2022GL101075. https://doi.org/10.1029/2022GL101075

Rights

This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain Mark 1.0

Subjects

Abstract

Tropospheric trends in long-lived source gases N2O and the chlorofluorocarbons cause trends in O3 through changes in their reactive product gases. Transport affects the product gases because it controls the distribution of the long-lived source gases. We find that large changes in tropical upwelling 10–5 hPa since 2012 have strengthened the northern branch of the upper stratospheric (UpS) transport circulation, dramatically altering the abundances of N2O and its odd nitrogen product gases, NOx and HNO3. Increased upwelling is connected to stronger and more frequent Quasi-Biennial Oscillation easterly winds at 10 hPa and above. We use simulations with and without time varying MERRA2 meteorology to quantify the impact of dynamical changes on O3 loss via the NOx and ClOx cycles. We find that dynamical impacts on these cycles explain the mid-stratospheric tropical O3 increase and Arctic UpS O3 decrease since 2005.