A first chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core

TitleA first chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core
Publication TypeJournal Article
Year of Publication2013
AuthorsRasmussen S.O, Abbott P.M, Blunier T., Bourne A.J, Brook E., Buchardt S.L, Buizert C, Chappellaz J., Clausen H.B, Cook E., Dahl-Jensen D., Davies S.M, Guillevic M., Kipfstuhl S., Laepple T., Seierstad I.K, Severinghaus JP, Steffensen J.P, Stowasser C., Svensson A., Vallelonga P., Vinther B.M, Wilhelms F., Winstrup M.
JournalClimate of the Past
Date Published2013/11
Type of ArticleArticle
ISBN Number1814-9324
Accession NumberWOS:000328274700020
Keywordsabrupt climate-change; age-differences; fallout tuffs; fractionation; gas-transport; grip ice; isotopic; last glacial period; polar ice; record; temperature-change

A stratigraphy-based chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core has been derived by transferring the annual layer counted Greenland Ice Core Chronology 2005 (GICC05) and its model extension (GICC05modelext) from the NGRIP core to the NEEM core using 787 match points of mainly volcanic origin identified in the electrical conductivity measurement (ECM) and dielectrical profiling (DEP) records. Tephra horizons found in both the NEEM and NGRIP ice cores are used to test the matching based on ECM and DEP and provide five additional horizons used for the timescale transfer. A thinning function reflecting the accumulated strain along the core has been determined using a Dansgaard-Johnsen flow model and an isotope-dependent accumulation rate parameterization. Flow parameters are determined from Monte Carlo analysis constrained by the observed depth-age horizons. In order to construct a chronology for the gas phase, the ice age-gas age difference (Delta age) has been reconstructed using a coupled firn densification-heat diffusion model. Temperature and accumulation inputs to the Delta age model, initially derived from the water isotope proxies, have been adjusted to optimize the fit to timing constraints from delta N-15 of nitrogen and high-resolution methane data during the abrupt onset of Greenland interstadials. The ice and gas chronologies and the corresponding thinning function represent the first chronology for the NEEM core, named GICC05modelext-NEEM-1. Based on both the flow and firn modelling results, the accumulation history for the NEEM site has been reconstructed. Together, the timescale and accumulation reconstruction provide the necessary basis for further analysis of the records from NEEM.

Short TitleClim. Past.
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