High-resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores

Abstract

Abstract. Records of chemical impurities from ice cores enable us to reconstruct the past deposition of aerosols onto polar ice sheets and alpine glaciers. Through this they allow us to gain insight into changes of the source, transport and deposition processes that ultimately determine the deposition flux at the coring location. However, the low concentrations of the aerosol species in the ice and the resulting high risk of contamination pose a formidable analytical challenge, especially if long, continuous and highly resolved records are needed. Continuous flow analysis, CFA, the continuous melting, decontamination and analysis of ice-core samples has mostly overcome this issue and has quickly become the de facto standard to obtain high-resolution aerosol records from ice cores after its inception at the University of Bern in the mid-1990s. Here, we present continuous records of calcium (Ca2+), sodium (Na+), ammonium (NH4+), nitrate (NO3-) and electrolytic conductivity at 1 mm depth resolution from the NGRIP (North Greenland Ice Core Project) and NEEM (North Greenland Eemian Ice Drilling) ice cores produced by the Bern Continuous Flow Analysis group in the years 2000 to 2011 (Erhardt et al., 2021). Both of the records were previously used in a number of studies but were never published in full 1 mm resolution. Alongside the 1 mm datasets we provide decadal averages, a detailed description of the methods, relevant references, an assessment of the quality of the data and its usable resolution. Along the way we will also give some historical context on the development of the Bern CFA system. The data is available in full 1 mm and 10-year-averaged resolution on PANGAEA (https://doi.org/10.1594/PANGAEA.935838, Erhardt et al., 2021)

Impact of subsurface crevassing on the depth-age relationship of high-alpine ice cores extracted at Col du Dôme between 1994 and 2012

“…Additional NO3and NH4 + data that are useful to derive dating by annual layer counting at CDD (Preunkert et al, 2000) were obtained in CDM ice with CFA measurements conducted at CEP along the whole ice core. Working conditions of the CFA analyses at CEP are detailed in Kaufmann et al (2008), Gfeller et al (2014) and Erhardt et al (2022). 100…”

A multi-ice-core, annual-layer-counted Greenland ice-core chronology for the last 3800 years: GICC21

“…Impurity records, measured by an international team coordinated by the University of Bern, were also obtained in the field and have a depth resolution similar to the East-GRIP dataset (Kaufmann et al, 2008) but, due to brittle ice, suffer from increasingly wide data gaps that make annuallayer identification difficult below around 750 m. Hence, we used ECM, Na + , Ca 2+ , NH + 4 , and NO − 3 for layer counting between 7.6 and 727.3 m depth. A detailed description of the NEEM CFA measurements and the dataset can be found in Erhardt et al (2021). An additional CFA dataset 1 contains the site specifications.…”

“…The corresponding data files are available at PANGAEA (https://doi.org/10.1594/PANGAEA.935838; Erhardt et al, 2021). EastGRIP CFA data are in the process of being released in a similar way, and a preliminary data file can be obtained from Tobias Erhardt until the data files are available at PANGAEA.…”

Evaluating the 11-year solar cycle and short-term 10Be deposition events with novel excess water samples from the EGRIP project

“…175 10 Be deposition is known to be highly seasonal, with maxima closely related to the enhanced stratospheretroposphere exchanges (STE) causing increased descent of 10 Be from the stratosphere, where most of the production takes place, to the troposphere (Stohl et al, 2003;Zheng et al, 2020;Spiegl et al, 2022). Moreover, one of the main complications of dealing with CFA systems is the possible smoothing of the signal locked in the ice (Erhardt et al, 2022;Kaufmann et al, 2008;Mekhaldi et al, 2017;Sigg et al, 1994). 10 Be ions may attach to 180 the walls of the plastic tube connecting the melt head to the centrifuge tubes, as 10 Be precipitates in a basic environment.…”