Low time resolution analysis of polar ice cores cannot detect impulsive nitrate events

TL;DR

This paper argues that low time resolution in polar ice core analysis prevents detection of impulsive nitrate events, questioning previous claims and emphasizing the need for higher-resolution sampling to better understand atmospheric and solar influences.

Contribution

It critiques prior studies' resolution limitations and advocates for re-examining ice cores with finer sampling to detect impulsive nitrate events and their potential links to solar activity.

Findings

Low resolution obscures impulsive nitrate signals

Current data cannot confirm SPE-related nitrate deposition

Re-examination with higher resolution is recommended

Abstract

Ice cores are archives of climate change and possibly large solar proton events (SPEs). Wolff et al. (2012) used a single event, a nitrate peak in the GISP2-H core, which McCracken et al. (2001a) time associated with the poorly quantified 1859 Carrington event, to discredit SPE-produced, impulsive nitrate deposition in polar ice. This is not the ideal test case. We critique the Wolff et al. analysis and demonstrate that the data they used cannot detect impulsive nitrate events because of resolution limitations. We suggest re-examination of the top of the Greenland ice sheet at key intervals over the last two millennia with attention to fine resolution and replicate sampling of multiple species. This will allow further insight into polar depositional processes on a sub-seasonal scale, including atmospheric sources, transport mechanisms to the ice sheet, post-depositional interactions, and a potential SPE association.