Ice-core evidence for a small solar-source at atmospheric nitrate

A precision-dated ice-core nitrate record from Law Dome, coastal East Antarctica is compared to the timing of known solar proton events and geomagnetic storms over the period 1888 to 1995. We find statistical evidence for a significant (P < 0.03) but small elevation in mean nitrate concentrations following the solar events (<similar to> 11% over the 12 months beginning 3 months post-event). While some solar events are identifiable in the nitrate record, most are not distinguishable from the background noisy signal (which has numerous large peaks), and some solar events show no nitrate elevation above even mean levels.