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The Mount Brown South ice core (MBS 69.111° S 86.312° E) is a new, high resolution ice core drilled in coastal East Antarctica. With mean annual accumulation estimated to be 20–30 cm ice equivalent accumulation throughout the length of the core (∼295 m), MBS represents a high resolution archive of ice core data spanning 1137 years (873–2009 CE), from an area previously underrepresented by high resolution ice core data. Here, we present a high-resolution dataset of chemistry and impurities obtained via continuous flow analysis (CFA). The dataset consists of meltwater electrolytic conductivity, sodium (Na+), ammonium (NH4+), hydrogen peroxide (H2O2), and insoluble microparticle measurements. The data are presented in three datasets: as a 1 mm depth resolution record, 3 cm averaged record, and decadal average record. The 1 mm record represents an oversampling of the true resolution, as due to smoothing effects the actual resolution is closer to 3 cm for some species. Therefore, the 3 cm resolution dataset is considered to be the minimum true resolution given the system setup. We also describe the current Copenhagen CFA system, and provide a detailed assessment of data quality, precision, and functional resolution. The 1 mm averaged, 3 cm averaged, and MBS2023 decadal averaged datasets are available at the Australian Antarctic Data Center: http://dx.doi.org/doi:10.26179/9tke-0s16 (Harlan et al., 2024). [ABSTRACT FROM AUTHOR]

There are enormous costs involved in transporting snow and ice samples to home laboratories for "simple" analyses in order to constrain annual layer thicknesses and identify accumulation rates of specific sites. It is well known that depositional noise, incurred from factors such as wind drifts, seasonally biased deposition and melt layers can influence individual snow and firn records and that multiple cores are required to produce statistically robust time series. Thus, at many sites, core samples are measured in the field for densification, but the annual accumulation and the content of chemical impurities are often represented by just one core to reduce transport costs. We have developed a portable "lightweight in situ analysis" (LISA) box for ice, firn and snow analysis that is capable of constraining annual layers through the continuous flow analysis of meltwater conductivity and hydrogen peroxide under field conditions. The box can run using a small gasoline generator and weighs less than 50 kg. The LISA box was tested under field conditions at the East Greenland Ice-core Project (EastGRIP) deep ice core drilling site in northern Greenland. Analysis of the top 2 m of snow from seven sites in northern Greenland allowed the reconstruction of regional snow accumulation patterns for the 2015–2018 period (summer to summer). [ABSTRACT FROM AUTHOR]

In ice cores continuous flow analysis (CFA) are often used to measure impurities, such as insoluble dust, conductivity and ions by means of fluorescence or absorption techniques after transport from the field to the laboratory. In such a system the ice core is melted on a melt head that separates the potential contaminated outer section from the untouched inner section. The inner melt water stream is then used for high resolution measurements of chemical impurities. However for fragile firn and snow core the transport from the field to the laboratory compromises the integrity of the samples. Here we present a novel developed Light In-Situ Analysis (LISA) - Portable Continuous Flow Analysis (CFA) box for determining chemical impurities in snow and firn directly, while still in the field. A preliminary version of the box has been tested successfully on 2 meter snow cores at the EastGRIP ice core drilling site in 2017 in Northeast Greenland at -22°C. This proof-of-concept device demonstrates that successful measurements can be conducted under open-field conditions to constrain conductivity and thus annual accumulation, but only one parameter (conductivity) was continuously measured. The box have been further optimized to include also opportunities for two sets of fluorescence measurements such as eg. peroxide, calcium or ammonium. In low accumulation sites in Greenland such proxies can be used to identify annual layers in the snow pack. In addition the density of the snow cores can be determined by monitoring the melt speed in combination with the energy used on melting. The two sets of measurements combined can provide the annual accumulation. [ABSTRACT FROM AUTHOR]