Spatial patterns of DO events in Greenland ice core chemistry

Deep ice core drilling efforts have been ongoing since the 1960’ and several records of Greenland impurities exist thanks to huge multiple nation efforts and the work of many dedicated people over the years and include Camp Century, Dye3, GRIP, GISP2, Renland, NGRIP, NEEM, RECAP and the new EGRIP ice core. 

The 25 Dansgaard-Oeschger (DO) events, first named in the Greenland ice core δ 18O signal from GRIP, are found in all deep Greenland ice cores with a significant corresponding signal also reflected in chemistry and impurities contained in the ice. 

 

Continuous flow analysis (CFA) is the preferred method  to investigate the long Greenland ice cores for their impurity content and often includes NH₄⁺ , Ca²⁺ , and Na⁺ ions, while Ion Chromtography (IC) was previously utilized. The chemical impurities besides being influenced by transport and accumulation patterns, provide information about forest fires, wind-blown dust, and sea ice, respectively. 

 

We show here CFA measurements performed in Copenhagen in 2019 on the Dye3 old core at depths of 1753–1820m and 1865–1918m representing both Holocene, Younger Dryas and Glacial sections (GS 5 to 12) and the high accumulation RECAP ice core CFA profile. The ReCAP ice core extends 584.11m and while the glacial section is strongly thinned and covers just 20 meters of the ReCAP core, it nonetheless due to the high resolution of the CFA measurements done in 2015 and 2016, cover all 25 expected DO event.

 

Here we present these two datasets of Dye 3 and RECAP by CFA done at University of Copenhagen and compare for DO'swith other central Greenland ice cores with the aim to constrain spatial patterns of DO events in Greenland ice core chemistry records.