"The most important result of this study is that there is a significant influence of stratospheric ozone on atmospheric large scale airflow patterns," Sascha Brand of the Alfred Wegener Institute told environmentalresearchweb. "Further, this influence is such that with interactive ozone chemistry there is more meridional [north-south] exchange of air masses and a less stable polar vortex (negative phase of the Arctic Oscillation)."

When the Arctic Oscillation is in its negative phase, the pressure over the North Pole is higher than normal and Europe and North America tend to experience cold winters. Since 1989 the oscillation has been in a positive phase.

"Since most past model simulations, using various models under various boundary conditions, showed too little meridional exchange and a too stable polar vortex, our results could help to improve existing and future climate models," said Brand.

Brand and colleagues incorporated a chemistry module into the atmosphere-ocean-sea ice general circulation model ECHO-G to create ECHO-GiSP – ECHO-G with Intengrated Straospheric chemistry. The module included 39 chemical species and 116 defined chemical reactions. It covered the main members of the Ox, NOx, ClOx, HOx and BrOx chemical families, as well as gases such as carbon monoxide, carbon dioxide, methane, nitrogen, hydrogen and water vapour. The researchers ran two 150 year simulations, one of which employed the interactive chemistry-dynamics coupling.

"We focused on interactive stratospheric ozone chemistry, since although it is well known that it’s mainly ozone that controls the stratospheric temperature distribution, there was little knowledge about its effects on stratospheric, and especially on tropospheric, circulation," said Brand.

Now Brand and colleagues plan to continue to analyse the model data from the existing interactive stratospheric ozone simulation and reference simulation, with a special focus on the Antarctic winter period. As a next step, they plan to "extend their stratospheric chemistry towards a more complex tropo- and stratospheric chemistry".

The researchers reported their work in Geophysical Research Letters.