Hamburg 2009 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

UP: Fachverband Umweltphysik

UP 1: Atmosphäre I

UP 1.3: Talk

Tuesday, March 3, 2009, 11:30–11:42, VMP 9 HS

Investigating the impact of solar proton events on the middle atmosphere on the basis of three dimensional model studies — •Nadine Wieters, Miriam Sinnhuber, Holger Winkler, Björn-Martin Sinnhuber, and Justus Notholt — Institut für Umweltphysik, Universität Bremen

In Bremen, stratospheric and mesospheric models of different complexity are available, including the new Bremen three-dimensional Chemistry and Transport Model (B3dCTM). It combines a state-of-the-art model of stratospheric chemistry with a three-dimensional transport scheme driven by analysed temperatures and wind-fields from ECMWF, covering an altitude range of 10-75 km.

During particle events caused by e.g. solar or geomagnetic storms the upper and middle atmosphere will be ionised. This ionisation will start fast ion chemistry reactions which lead to an increase of odd hydrogen (HOx) and nitrogen (NOx) constituents which both destroy ozone in catalytic cycles. NOx is very long-lived in the middle atmosphere and can be transported down into the middle and lower stratosphere es- pecially during polar winter, where it will then effectively destroy ozone.

To simulate these particle events, parameterisations of HOx and NOx production as a function of atmospheric ionisation have been implemented into the model, and the model is driven by ionisation rates based on measured proton fluxes.

Model studies for different solar proton events have been carried out and results for NOx and ozone will be presented.