Seasonal-Scale Dating of a Shallow Ice Core From Greenland Using Oxygen Isotope Matching Between Data and Simulation

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Furukawa, Ryoto, Uemura, Ryu, Fujita, Koji, Sjolte, Jesper, Yoshimura, Kei, Matoba, Sumito, Iizuka, Yoshinori
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union
• Subjects: 450; Arctic; Greenland; ice core; Sea ice
• Online Access: http://hdl.handle.net/2115/70252; https://doi.org/10.1002/2017JD026716

A precise age scale based on annual layer counting is essential for investigating pastenvironmental changes from ice core records. However, subannual scale dating is hampered by theirregular intraannual variabilities of oxygen isotope (δ18O) records. Here we propose a dating method basedon matching the δ18O variations between ice core records and records simulated by isotope-enabled climatemodels. We applied this method to a new δ18O record from an ice core obtained from a dome site insoutheast Greenland. The close similarity between the δ18O records from the ice core and models enablescorrelation and the production of a precise age scale, with an accuracy of a few months. A missing δ18Ominimum in the 1995/1996 winter is an example of an indistinct δ18O seasonal cycle. Our analysis suggeststhat the missing δ18O minimum is likely caused by a combination of warm air temperature, weak moisturetransport, and cool ocean temperature. Based on the age scale, the average accumulation rate from 1960 to2014 is reconstructed as 1.02 m yr-1in water equivalent. The annual accumulation rate shows an increasingtrend with a slope of 3.6 mm yr-1, which is mainly caused by the increase in the autumn accumulationrate of 2.6 mm yr-1. This increase is likely linked to the enhanced hydrological cycle caused by the decreasein Arctic sea ice area. Unlike the strong seasonality of precipitation amount in the ERA reanalysis data in thesoutheast dome region, our reconstructed accumulation rate suggests a weak seasonality.