Anomalous nitrate concentrations in polar ice cores—Do they result from solar particle injections into the polar atmosphere?

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Abstract
Nitrate concentrations and electrical conductivity in an ice core from central Greenland have been measured simultaneously on 1.5 cm sections along the entire length of the 122 m core. This method of micro‐resolution (time resolution is 1 week‐1 month) provides for statistically significant determinations of rapid variations in nitrate fallout from the polar stratosphere superimposed on a background from all other sources. The seasonal NO3− background variations and the volcanic signal contained in the electrical conductivity data provide accurate dating of the ice core. This type of micro‐resolution nitrate measurement appears to be useful as a tool to investigate the possible sources of polar nitrate anomalies such as solar proton events.