Stratospheric chemistry in the NZESM

Improving the simulation of stratospheric chemistry in the NZESM

The aim of this project is mainly to improve the simulation of stratospheric chemistry in the NZ Earth Systems Model (NZESM). Stratospheric ozone is particularly relevant to climate change in the southern hemisphere because of the emergence, in every spring, of the ozone hole above Antarctica.


Ozone depletion is a major (and, seasonally, the dominant) driver of southern hemisphere climate change. However, problems with simulating ozone means it’s difficult to have confidence that the extent of its influence is properly represented in the model. This work improves the simulation of stratospheric ozone depletion, and in particular Antarctic ozone depletion, to contribute to a more realistic simulation of southern hemisphere climate and its response to human activity.

This project builds on a strong heritage in stratospheric model development in New Zealand and complements the work of our international partners in earth system modelling. We’re collaborating closely with another Deep South Challenge project (Evaluating the NZESM against modern & historical observations) that will produce observational datasets to help us validate the NZESM. We’re also strengthening a long-standing relationship with Australian colleagues interested in climate–ozone links.



This project in the media:
Just the ticket! Not one, not two, but up to four “tickets” to improve the world’s centralised global climate model Deep South Challenge news story
New Zealand's Next Top Model, New Zealand Geographic
Breaking the ice, NIWA

Research and findings:
Tropical circulation and precipitation response to ozone depletion and recovery, Stefan Brönnimann et al, Environmental Research Letters
The evolution of zonally asymmetric austral ozone in a chemistry–climate model, Fraser Dennison et al, Atmospheric Chemistry and Physics
Stratospheric Chemistry in the NZESM, Fraser Dennison et al, Deep South Symposium