Seasonal‐Scale Dating of a Shallow Ice Core From Greenland Using Oxygen Isotope Matching Between Data and Simulation. Issue 20 (26th October 2017)

• Record Type: Journal Article
• Authors: Furukawa, Ryoto; Uemura, Ryu; Fujita, Koji; Sjolte, Jesper; Yoshimura, Kei; Matoba, Sumito; Iizuka, Yoshinori
• Is Part Of: Journal of geophysical research. Volume 122:Issue 20(2017)
• Page Start: 10, 873
• Page End: 10, 887
• Publication Date: 2017-10-26
• Subjects: Greenland -- accumulation -- isotope -- GCM -- ERA -- sea ice; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2017JD026716
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: A precise age scale based on annual layer counting is essential for investigating past environmental changes from ice core records. However, subannual scale dating is hampered by the irregular intraannual variabilities of oxygen isotope (δ 18 O) records. Here we propose a dating method based on matching the δ 18 O variations between ice core records and records simulated by isotope‐enabled climate models. We applied this method to a new δ 18 O record from an ice core obtained from a dome site in southeast Greenland. The close similarity between the δ 18 O records from the ice core and models enables correlation and the production of a precise age scale, with an accuracy of a few months. A missing δ 18 O minimum in the 1995/1996 winter is an example of an indistinct δ 18 O seasonal cycle. Our analysis suggests that the missing δ 18 O minimum is likely caused by a combination of warm air temperature, weak moisture transport, and cool ocean temperature. Based on the age scale, the average accumulation rate from 1960 to 2014 is reconstructed as 1.02 m yr −1 in water equivalent. The annual accumulation rate shows an increasing trend with a slope of 3.6 mm yr −1, which is mainly caused by the increase in the autumn accumulation rate of 2.6 mm yr −1 . This increase is likely linked to the enhanced hydrological cycle caused by the decrease in Arctic sea ice area. Unlike the strong seasonality of precipitation amount in the ERA reanalysis data in the southeast dome region, our reconstructed accumulation rate suggests a weak seasonality. Key Points: An oxygen isotope record from southeast Greenland revealed that isotope‐enabled models reproduce well the interannual and intraannual variations The similar intraannual variations enable us to construct a precise age scale by fitting oxygen isotope data to a simulated template record The reconstructed snow accumulation rate shows an increasing trend over the past 54 years, with a dominant contribution of autumn snow