Production rate of NO in 1/Ionpair as computed with the ion chemistry model UBIC for the solar event of October 2003.
The University of Bremen Ion Chemistry model (UBIC) is a tool to compute the production and loss rates of neutral species by ion chemistry reactions. The model is driven by the ion pair production rates due to particles and photo-ionisation, and requires an initial neutral atmosphere as input. It then solves a system of differential equations for both neutral and ionic reactants numerically. The routine of UBIC is based on the fact that ion chemical reactions are extremely fast, and photochemical equilibrium is reached after a comparably short time for the ionic constituents. Hence, UBIC can be called by a superordinate model of the neutral atmosphere, computing a photochemical equilibrium of the ionic constituents, considering the initial atmosphere and the forcing at the starting time. It is assumed that forcing and neutral atmospheric composition do not change significantly while the ion reactions are simulated. UBIC returns formation and loss rates for the neutral species such as NOx which participate in ionic reactions. These results are then used in the superordinate model of the neutral atmosphere.
UBIC was developed by Holger Winkler at the Institute of Environmental Physics, University of Bremen, in the research group of M. Sinnhuber, in the framework of the German priority programmes "geomagnetic activity" and CAWSES.
See also: Winkler, H., Kazeminejad, S., Sinnhuber, M., Kallenrode, M.-B., and Notholt, J., The conversion of mesospheric HCl into active chlorine during the solar proton event in July 2000 in the northern polar region, J. Geophys. Res., 114, D00I03, 2009