A semi-empirical model of the stratosphere in the Antarctic climate system

posted 6 Apr 2014, 16:01 by Bodeker Scientific   [ updated 6 Apr 2014, 18:24 ]
During his visit at Bodeker Scientific in March 2014 A/Prof. Malte Meinshausen implemented a few subroutines related to the new interactive stratospheric module in MAGICC. The stratospheric module is currently being developed at Bodeker Scientific.

In the current version of the MAGICC SCM (Simple Climate Model) stratospheric ozone changes depend only on equivalent effective stratospheric chlorine (EESC). Within the NZARI project, MAGICC is being extended to include an interactive stratospheric ozone layer. This new stratospheric component, referred to as SWIFT (semi-empirical weighted iterative fit technique) describes the time rate of change through the winter of key species in the polar stratosphere. SWIFT is driven by time series of the Fractional Area of the Polar vortex experiencing temperatures below 195K (FAP) and Fractional Area of the Polar vortex exposed to sunlight (FAS). FAP is calculated from temperature fields which are obtained from a module called STePS (Stratospheric Temperature Pattern Scaling). A pattern scaling technique, using a least squares approach, will be applied to STePS to determine the functional dependence of stratospheric temperature on CO2 and ozone. The same pattern scaling technique is used to determine the dependence of stratospheric column ozone on EESC (Equivalent Effective Stratospheric Chlorine) and CO2, and also to determine the dependence on radiative forcing on stratospheric ozone. During A/Prof. Malte Meinshausen’s visit the subroutines related to this new stratospheric module were implemented in MAGICC. The modules that will be used to calculate stratospheric ozone as a function of EESC and CO2 are currently being developed at Bodeker Scientific. The stratospheric ozone is trained on EMAC daily data. With a stratospheric component like this included in an SCM, it will be possible to simulate the Antarctic ozone hole for a wide range of greenhouse gases and ozone depleting substances.

For more information about the semi-empirical model of the stratosphere in the Antarctic climate system, click here.