Chemical modifications of the middle atmosphere are a link between climate and other solar-terrestrial phenomena. The role of high-altitude discharges, e.g. sprites, in this context is at present unclear.Within the European research network CAL (Coupling of Atmospheric Layers), the possible chemical impact of sprites will therefore be studied. The Sodankylä Ion Chemistry (SIC) model is at present a 1-dimensional, coupled neutral and ion chemistry model of the region between 50 and 100 km altitude. This model will be modified in order to account for processes relevant in sprite studies, such as separation of neutral, electron and ion temperatures and reactions with excited states of the constituents. The updated model will then be used to quantify those chemical modifications which can give rise to altered radiative and dynamic balance.