EGU2020-22211
https://doi.org/10.5194/egusphere-egu2020-22211
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Emergence of Southern Hemisphere circulation changes in response to ozone recovery

Brian Zambri1, Susan Solomon1, David Thompson2, and Qiang Fu3
Brian Zambri et al.
  • 1Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, Massachusetts, United States of America (bzambri@mit.edu)
  • 2Colorado State University, Department of Atmospheric Science, Fort Collins, Colorado, United States of America
  • 3University of Washington, Seattle, Atmospheric Sciences Department, Seattle, Washington, United States of America

Ozone depletion in the Southern Hemisphere (SH) stratosphere in the late 20th century cooled the air there, strengthening the SH stratospheric westerly winds near 60ºS and altering SH surface climate. Since ~1999, trends in Antarctic ozone have begun to recover, exhibiting a flattening followed by a sign reversal in response to decreases in stratospheric chlorine concentration due to the Montreal Protocol, an international treaty banning the production and consumption of ozone-depleting substances. Here we show that the post–1999 increase in ozone has resulted in thermal and circulation changes of opposite sign to those that resulted from stratospheric ozone losses, including a warming of the SH polar lower stratosphere and a weakening of the SH stratospheric polar vortex.  Further, these altered trends extend to the upper troposphere, albeit of smaller magnitudes.  Observed post–1999 trends of temperature and circulation in the stratosphere are about 20–25% the magnitude of those of the ozone depletion era, and are broadly consistent with expectations based on modeled depletion-era trends and variability of both ozone and reactive chlorine, thereby indicating the emergence of healing of dynamical impacts of the Antarctic ozone hole.

How to cite: Zambri, B., Solomon, S., Thompson, D., and Fu, Q.: Emergence of Southern Hemisphere circulation changes in response to ozone recovery, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22211, https://doi.org/10.5194/egusphere-egu2020-22211, 2020