MBS2023 - The Mount Brown South ice core chronologies and chemistry data

Full description

This dataset contains the layer counted annual horizon depths (chronologies) of the Mount Brown South ice cores drilled in 2017/2018 at an elevation of 2,084 metres on the boundary of Princess Elizabeth and Kaiser Wilhelm II Land in East Antarctica (the 'MBS1718 ice cores'). The chronologies were developed using a site-specific annual layer-counting methodology which employed seasonally varying trace chemical species and stable water isotope ratios, combined with alignment to known volcanic horizons. The chronologies include the ‘Main’ 295 m record spanning 1,137 years (873-2009 CE), and three surface cores spanning the most recent 39-52 years up to the surface age at the time of drilling (austral summer 2017/2018). The MBS chronologies presented here are collectively named 'MBS2023' to differentiate them from any possible future changes to the age-by-depth scales, which would result in a new and different chronology. MBS2023 is synchronized to the WAIS Divide ice core chronology, 'WD2014'. In addition this dataset includes the trace impurities data for the 'Main' and surface ice core records, on a depth scale and with annual horizon dates from MBS2023. Note that the within year dates are calculated assuming uniform annual accumulation, and thus should be interpreted as estimates based on this assumption. See Crockart et al., 2021 and Jackson et al., 2023 for more information on the variability inherent in the annual snowfall accumulation regime at Mount Brown South: https://cp.copernicus.org/articles/17/1795/2021/cp-17-1795-2021.pdf and https://cp.copernicus.org/articles/19/1653/2023/. A full description of the age scales, datasets and the development of the chronologies is detailed in Vance et al. (2024), 'An annually resolved chronology for the Mount Brown South ice cores, East Antarctica', at https://cp.copernicus.org/articles/20/969/2024/cp-20-969-2024.pdf.

The stable water isotope datasets associated with the 'MBS1718 ice cores' are available separately. The 'Main' isotope dataset can be found here: "An 1135 year very high-resolution water isotope record of polar precipitation from the Indo-Pacific sector of East Antarctica", described by the doi:10.26179/ygeq-1a95, and the surface core dataset can be found here: "The Mount Brown South surface core (MBS1718 'Alpha', 'Bravo', and 'Charlie') chronologies and stable water isotope records" described by the doi:10.26179/372t-4q89

Lineage

Progress Code: completed

Statement: There were no issues with data collection or analysis. Contacting the authors of this dataset is recommended prior to use of the data in order to understand the dataset, missing values, analytical aspects of the MSA, nitrate and fluoride data, and how the assumption of uniform annual snowfall accumulation can affect the accuracy of within year dates. Please refer to the published journal articles in Climate of the Past indicated above for more information.

Notes

Purpose
The purpose of this dataset is to provide the assigned annual layer dates (in year CE) by depth for the Mount Brown South Main and surface cores drilled in 2017 / 2018, and the seasonally varying chemistry species used to identify and count the annual layers. Note that the within year dating in the chemistry data reflects an assumption of a uniform snowfall accumulation regime at the site (which is not necessarily realistic for the Mount Brown South site) thus the within year dates should not be assumed to be accurate.