Sensitivity of the southern hemisphere circumpolar jet response to Antarctic ozone depletion: prescribed versus interactive chemistry.

Haase, Sabine , Fricke, Jaika, Kruschke, Tim , Wahl, Sebastian and Matthes, Katja (2020) Sensitivity of the southern hemisphere circumpolar jet response to Antarctic ozone depletion: prescribed versus interactive chemistry. Open Access Atmospheric Chemistry and Physics, 20 . pp. 14043-14061. DOI 10.5194/acp-20-14043-2020.

[thumbnail of acp-20-14043-2020.pdf]
Preview
Text
acp-20-14043-2020.pdf - Published Version
Available under License Creative Commons: Attribution 4.0.

Download (30MB) | Preview
[thumbnail of acp-20-14043-2020-supplement.pdf]
Preview
Text
acp-20-14043-2020-supplement.pdf - Supplemental Material
Available under License Creative Commons: Attribution 4.0.

Download (10MB) | Preview

Supplementary data:

Abstract

Southern hemisphere lower stratospheric ozone depletion has been shown to lead to a poleward shift of the tropospheric jet stream during austral summer, influencing surface atmosphere and ocean conditions, such as surface temperatures and sea ice extent. The characteristics of stratospheric and tropospheric responses to ozone depletion, however, differ largely among climate models depending on the representation of ozone in the models.

The most accurate way to represent ozone in a model is to calculate it interactively. However, due to computational costs, in particular for long-term coupled ocean-atmosphere model integrations, the more common way is to prescribe ozone from observations or calculated model fields. Here, we investigate the difference between an interactive and a specified chemistry version of the same atmospheric model in a fully-coupled setup using a 9-member chemistry-climate model ensemble. In the specified chemistry version of the model the ozone fields are prescribed using the output from the interactive chemistry model version. In contrast to earlier studies, we use daily-resolved ozone fields in the specified chemistry simulations to achieve a better comparability between the ozone forcing with and without interactive chemistry. We find that although the short-wave heating rate trend in response to ozone depletion is the same in the different chemistry settings, the interactive chemistry ensemble shows a stronger trend in polar cap stratospheric temperatures (by about 0.7 K per decade) and circumpolar stratospheric zonal mean zonal winds (by about 1.6 m/s per decade) as compared to the specified chemistry ensemble. This difference between interactive and specified chemistry in the stratospheric response to ozone depletion also affects the tropospheric response, namely the poleward shift of the tropospheric jet stream. We attribute part of these differences to the missing representation of feedbacks between chemistry and dynamics in the specified chemistry ensemble, which affect the dynamical heating rates, and part of it to the lack of spatial asymmetries in the prescribed ozone fields. This effect is investigated using a sensitivity ensemble that was forced by a three-dimensional instead of a two–dimensional ozone field.

This study emphasizes the value of interactive chemistry for the representation of the southern hemisphere tropospheric jet response to ozone depletion and infers that for periods with strong ozone variability (trends) the details of the ozone forcing can be crucial for representing southern hemispheric climate variability.

Document Type: Article
Keywords: Dynamics; Atmospheric Modelling; Stratosphere; Physics (physical properties and processes)
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Refereed: Yes
Open Access Journal?: Yes
Publisher: Copernicus Publications (EGU)
Related URLs:
Date Deposited: 03 Jun 2020 07:18
Last Modified: 08 Feb 2023 09:39
URI: https://oceanrep.geomar.de/id/eprint/49792

Actions (login required)

View Item View Item