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Climate information preserved in seasonal water isotope at NEEM : Relationships with temperature, circulation and sea ice

Zheng, Minjie LU ; Sjolte, Jesper LU orcid ; Adolphi, Florian LU ; Møllesøe Vinther, Bo ; Steen-Larsen, Hans Christian ; Popp, Trevor James and Muscheler, Raimund LU orcid (2018) In Climate of the Past 14(7). p.1067-1078
Abstract

Analyzing seasonally resolved δ18O ice core data can aid the interpretation of the climate information in ice cores, also providing insights into factors governing the δ18O signal that cannot be deciphered by investigating the annual δ18O data only. However, the seasonal isotope signal has not yet been investigated in northern Greenland, e.g., at the NEEM (North Greenland Eemian Ice Drilling) ice core drill site. Here, we analyze seasonally resolved δ18O data from four shallow NEEM ice cores covering the last 150 years. Based on correlation analysis with observed temperature, we attribute about 70 and 30%of annual accumulation to summer and winter, respectively. The NEEM summer δ18O... (More)

Analyzing seasonally resolved δ18O ice core data can aid the interpretation of the climate information in ice cores, also providing insights into factors governing the δ18O signal that cannot be deciphered by investigating the annual δ18O data only. However, the seasonal isotope signal has not yet been investigated in northern Greenland, e.g., at the NEEM (North Greenland Eemian Ice Drilling) ice core drill site. Here, we analyze seasonally resolved δ18O data from four shallow NEEM ice cores covering the last 150 years. Based on correlation analysis with observed temperature, we attribute about 70 and 30%of annual accumulation to summer and winter, respectively. The NEEM summer δ18O signal correlates strongly with summer western Greenland coastal temperature and with the first principal component (PC1) of summer δ18O from multiple seasonally resolved ice cores from central/southern Greenland. However, there are no significant correlations between NEEM winter δ18O data and western Greenland coastal winter temperature or southern/central Greenland winter δ18O PC1. The stronger correlation with temperature during summer and the dominance of summer precipitation skew the annual δ18O signal in NEEM. The strong footprint of temperature in NEEM summer δ18O record also suggests that the summer δ18O record rather than the winter δ18O record is a better temperature proxy at the NEEM site. Despite the dominant signal of the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO) in the central?southern ice core data, both NAO and AMO exert weak influences on NEEM seasonal δ18O variations. The NEEM seasonal δ18O is found to be highly correlated with Baffin Bay sea ice concentration (SIC) in the satellite observation period (1979?2004), suggesting a connection of the sea ice extent with δ18O at NEEM. NEEM winter δ18O significantly correlates with SIC even for the period prior to satellite observation (1901? 1978). The NEEM winter δ18O may reflect sea ice variationsof Baffin Bay rather than temperature itself. This study shows that seasonally resolved δ18O records, especially for sites with a seasonal precipitation bias such as NEEM, provide a better understanding of how changing air temperature and circulation patterns are associated with the variability in the δ18O records.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Climate of the Past
volume
14
issue
7
pages
12 pages
publisher
Copernicus GmbH
external identifiers
  • scopus:85050673024
ISSN
1814-9324
DOI
10.5194/cp-14-1067-2018
project
Disentangling climate influence and production rate on 10Be deposition in the polar region over the last 150 yrs
Disentangling production and climate signals from high-resolution Beryllium records: implications for solar and geomagnetic reconstructions
language
English
LU publication?
yes
id
dcc2cf31-5566-49c4-b00b-a2566dac986f
date added to LUP
2018-08-21 10:40:27
date last changed
2021-10-06 01:46:02
@article{dcc2cf31-5566-49c4-b00b-a2566dac986f,
  abstract     = {<p>Analyzing seasonally resolved δ<sup>18</sup>O ice core data can aid the interpretation of the climate information in ice cores, also providing insights into factors governing the δ<sup>18</sup>O signal that cannot be deciphered by investigating the annual δ<sup>18</sup>O data only. However, the seasonal isotope signal has not yet been investigated in northern Greenland, e.g., at the NEEM (North Greenland Eemian Ice Drilling) ice core drill site. Here, we analyze seasonally resolved δ<sup>18</sup>O data from four shallow NEEM ice cores covering the last 150 years. Based on correlation analysis with observed temperature, we attribute about 70 and 30%of annual accumulation to summer and winter, respectively. The NEEM summer δ<sup>18</sup>O signal correlates strongly with summer western Greenland coastal temperature and with the first principal component (PC1) of summer δ<sup>18</sup>O from multiple seasonally resolved ice cores from central/southern Greenland. However, there are no significant correlations between NEEM winter δ<sup>18</sup>O data and western Greenland coastal winter temperature or southern/central Greenland winter δ<sup>18</sup>O PC1. The stronger correlation with temperature during summer and the dominance of summer precipitation skew the annual δ<sup>18</sup>O signal in NEEM. The strong footprint of temperature in NEEM summer δ<sup>18</sup>O record also suggests that the summer δ<sup>18</sup>O record rather than the winter δ<sup>18</sup>O record is a better temperature proxy at the NEEM site. Despite the dominant signal of the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO) in the central?southern ice core data, both NAO and AMO exert weak influences on NEEM seasonal δ<sup>18</sup>O variations. The NEEM seasonal δ<sup>18</sup>O is found to be highly correlated with Baffin Bay sea ice concentration (SIC) in the satellite observation period (1979?2004), suggesting a connection of the sea ice extent with δ<sup>18</sup>O at NEEM. NEEM winter δ<sup>18</sup>O significantly correlates with SIC even for the period prior to satellite observation (1901? 1978). The NEEM winter δ<sup>18</sup>O may reflect sea ice variationsof Baffin Bay rather than temperature itself. This study shows that seasonally resolved δ<sup>18</sup>O records, especially for sites with a seasonal precipitation bias such as NEEM, provide a better understanding of how changing air temperature and circulation patterns are associated with the variability in the δ<sup>18</sup>O records.</p>},
  author       = {Zheng, Minjie and Sjolte, Jesper and Adolphi, Florian and Møllesøe Vinther, Bo and Steen-Larsen, Hans Christian and Popp, Trevor James and Muscheler, Raimund},
  issn         = {1814-9324},
  language     = {eng},
  month        = {07},
  number       = {7},
  pages        = {1067--1078},
  publisher    = {Copernicus GmbH},
  series       = {Climate of the Past},
  title        = {Climate information preserved in seasonal water isotope at NEEM : Relationships with temperature, circulation and sea ice},
  url          = {http://dx.doi.org/10.5194/cp-14-1067-2018},
  doi          = {10.5194/cp-14-1067-2018},
  volume       = {14},
  year         = {2018},
}