scholarly journals A glaciochemical study of 120 m ice core from Mill Island, East Antarctica

2016 ◽  
Author(s):  
Mana Inoue ◽  
Mark A. J. Curran ◽  
Andrew D. Moy ◽  
Tas D. van Ommen ◽  
Alexander D. Fraser ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Sea Ice ◽  
Ice Core ◽  
Chemical Species ◽  
Snow Accumulation ◽  
Sea Salt ◽  
East Antarctica ◽  
Ion Chemistry ◽  
Sea Ice Concentration ◽  
Ice Concentration

Abstract. A 120 m ice core was drilled on Mill Island, East Antarctica (65°30’ S, 100°40’ E) during the 2009/2010 Australian Antarctic field season. Contiguous discrete 5 cm samples were measured for hydrogen peroxide, water stable isotopes and trace ion chemistry. The ice core was annually dated using a combination of chemical species and water stable isotopes. The Mill Island ice core preserves a climate record covering 97 years from 1913 to 2009 C.E., with a mean snow accumulation of 1.35 m (ice-equivalent) per year (mIE yr−1). This northernmost East Antarctic coastal ice core site displays trace ion concentrations that are generally higher than other Antarctic ice core sites (e.g., mean sodium levels were 254 μEq L−1). The trace ion record at Mill Island is characterised by a unique and complex chemistry record with three distinct regimes identified. The trace ion record in Regime A displays clear seasonality from 2000 to 2009 C.E.; Regime B displays elevated concentrations with no seasonality from 1934 to 2000 C.E.; and Regime C displays relatively low concentrations with seasonality from 1913 to 1934 C.E. Sea salts were compared with instrumental data, including atmospheric models and satellite-derived sea ice concentration, to investigate influences on the Mill Island ice core record. The mean annual sea salt record does not correlate with wind speed. Instead, sea ice concentration to the east of Mill Island likely influences the annual mean sea salt record. A mechanism involving formation of frost flowers on sea ice is proposed to explain the extremely high sea salt concentration. The Mill Island ice core records are unexpectedly complex, with strong modulation of the trace chemistry on long timescales.

scholarly journals A glaciochemical study of the 120 m ice core from Mill Island, East Antarctica

2017 ◽  
Vol 13 (5) ◽  
pp. 437-453 ◽  
Author(s):  
Mana Inoue ◽  
Mark A. J. Curran ◽  
Andrew D. Moy ◽  
Tas D. van Ommen ◽  
Alexander D. Fraser ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Sea Ice ◽  
Ice Core ◽  
Chemical Species ◽  
Snow Accumulation ◽  
Sea Salt ◽  
East Antarctica ◽  
Ion Chemistry ◽  
Sea Ice Concentration ◽  
Ice Concentration

Abstract. A 120 m ice core was drilled on Mill Island, East Antarctica (65°30′ S, 100°40′ E) during the 2009/2010 Australian Antarctic field season. Contiguous discrete 5 cm samples were measured for hydrogen peroxide, water stable isotopes, and trace ion chemistry. The ice core was annually dated using a combination of chemical species and water stable isotopes. The Mill Island ice core preserves a climate record covering 97 years from 1913 to 2009 CE, with a mean snow accumulation of 1.35 m (ice-equivalent) per year (mIE yr−1). This northernmost East Antarctic coastal ice core site displays trace ion concentrations that are generally higher than other Antarctic ice core sites (e.g. mean sodium levels were 254 µEq L−1). The trace ion record at Mill Island is characterised by a unique and complex chemistry record with three distinct regimes identified. The trace ion record in regime A displays clear seasonality from 2000 to 2009 CE; regime B displays elevated concentrations with no seasonality from 1934 to 2000 CE; and regime C displays relatively low concentrations with seasonality from 1913 to 1934 CE. Sea salts were compared with instrumental data, including atmospheric models and satellite-derived sea-ice concentration, to investigate influences on the Mill Island ice core record. The mean annual sea salt record does not correlate with wind speed. Instead, sea-ice concentration to the east of Mill Island likely influences the annual mean sea salt record. A mechanism involving formation of frost flowers on sea ice is proposed to explain the extremely high sea salt concentration. The Mill Island ice core records are unexpectedly complex, with strong modulation of the trace chemistry on long timescales.

scholarly journals Coastal ice-core record of recent northwest Greenland temperature and sea-ice concentration

2015 ◽  
Vol 61 (230) ◽  
pp. 1137-1146 ◽  
Author(s):  
Erich C. Osterberg ◽  
Robert L. Hawley ◽  
Gifford Wong ◽  
Ben Kopec ◽  
David Ferris ◽  
...  
Keyword(s):  
Sea Ice ◽  
Regional Climate ◽  
Ice Core ◽  
Methanesulfonic Acid ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Multilinear Regression ◽  
Sea Ice Concentration ◽  
Baffin Bay ◽  
Ice Concentration

AbstractCoastal ice cores provide an opportunity to investigate regional climate and sea-ice variability in the past to complement hemispheric-scale climate reconstructions from ice-sheet-interior ice cores. Here we describe robust proxies of Baffin Bay temperature and sea-ice concentration from the coastal 2Barrel ice core collected in the Thule region of northwest Greenland. Over the 1990–2010 record, 2Barrel annually averaged methanesulfonic acid (MSA) concentrations are significantly correlated with May–June Baffin Bay sea-ice concentrations and summer temperatures. Higher MSA is observed during warmer years with less sea ice, indicative of enhanced primary productivity in Baffin Bay. Similarly, 2Barrel annually averaged deuterium excess (d-excess) values are significantly correlated with annual Baffin Bay sea-ice concentrations and summer and annual temperatures. Warm (cool) years with anomalously low (high) sea-ice concentration are associated with proportionally more (less) low-d-excess Baffin Bay moisture at the ice-core site. Multilinear regression models incorporating 2Barrel MSA, d-excess and snow accumulation account for 38–51% of the Baffin Bay sea-ice and temperature variance. The annual temperature model is significantly correlated with temperatures throughout most of Greenland and eastern Arctic Canada due to the strong influence of the North Atlantic Oscillation and Atlantic Multidecadal Oscillation.

scholarly journals Sea ice and large-scale atmospheric variability around East Antarctica

2021 ◽  
Author(s):  
◽  
Florence Isaacs
Keyword(s):  
Indian Ocean ◽  
Climate Variability ◽  
Sea Ice ◽  
Large Scale ◽  
Wave Train ◽  
East Antarctica ◽  
Sea Ice Concentration ◽  
Atmospheric Wave ◽  
Ice Concentration ◽  
Dronning Maud Land

<p><b>​​Antarctica’s sea ice cover is an important component in the global climate system. The variability and recent trends of sea ice concentration are, however, not accurately reproduced by models. Evaluating model performance is hampered because the processes that determine sea ice distribution are not yet well understood, particularly in the East Antarctic region. Here I explore the relationships between recent climate variability and sea ice around East Antarctica, the spatial variability in these relationships, and the impacts that these may have on other aspects of the climate and cryosphere. To achieve this, I analysed satellite-derived HadlSST sea ice concentration (SIC) alongside ERA5 atmospheric reanalysis data for the period between 1979-2018.</b></p> <p>I found that variability in sea ice coverage around East Antarctica was affected by El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), the Southern Annular Mode (SAM), and Zonal Wave 3 (ZW3). Additionally, I found that the influence of each of these modes varied spatially and temporally, and that sea ice variability affected how regional scale climate responded to changes in large-scale circulation. Summer and autumn SIC around Dronning Maud Land between 10°E and 70°E exhibited a statistically significant negative correlation with the Niño 3.4 index. Analysis of ERA5 data suggests that a southward‐propagating atmospheric wave train triggered by SST anomalies in the tropical Pacific extends into Dronning Maud Land and alters sea ice concentration by encouraging meridional airflow. Shifts in meridional flow in Dronning Maud Land affected sea ice thermodynamically, by altering local heat transport and in turn altering sea ice formation and melt. </p> <p>Sea ice around the Western Pacific sector (WPS) of East Antarctica showed a significant association with variability in the IOD and the SAM. The IOD was correlated with SIC in all seasons but summer. The IOD-SIC relationship is likely driven by an IOD-associated atmospheric wave-train which propagates polewards from the tropical Indian Ocean to Wilkes Land, altering regional circulation and in turn affecting SIC through changes to local climate and sea ice transport. The correlation between WPS SIC and the SAM shifts from positive in summer and autumn to negative in winter and spring, and is likely due to the influence of the SAM on katabatic winds and coastal polynyas, which in turn affect SIC. </p> <p>A significant correlation was observed between SIC variability around East Antarctica and precipitation variability across the continent and the near-coastal Southern Ocean. Further analysis showed that SIC affected how continental precipitation responded to large-scale atmospheric circulation, including modes such as ZW3 and the SAM. Specifically, increased southward moisture flux was only associated with increased precipitation in the inland coastal regions of the continent when SIC was anomalously low. These findings suggest that any future decrease in sea ice may result in greater coupling of climate variability with continental precipitation.</p>

scholarly journals A 125-year record of climate and chemistry variability at the Pine Island Glacier ice divide, Antarctica

2016 ◽  
Author(s):  
Franciele Schwanck ◽  
Jefferson C. Simões ◽  
Michael Handley ◽  
Paul A. Mayewski ◽  
Jeffrey D. Auger ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Trace Element ◽  
Ice Core ◽  
Sea Salt ◽  
Sea Surface ◽  
The West ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
Glacier Ice

Abstract. The Mount Johns (MJ) ice core (79º55' S; 94º23' W) was drilled near the Pine Island Glacier ice divide on the West Antarctic Ice Sheet during the 2008–2009 austral summer, to a depth of 92.26 m. The upper 45 m of the record covers approximately 125 years (1883–2008) showing marked seasonal variability. Trace element concentrations in 2,137 samples were determined using inductively coupled plasma mass spectrometry. In this study, we reconstruct mineral dust and sea salt aerosol transport and investigate the influence of climate variables on the elemental concentrations to the MJ site. The ice core record reflects changes in emissions as well as atmospheric circulation and transport processes. Our trajectory analysis shows distinct seasonality, with strong westerly transport in the winter months and a secondary northeasterly transport in the summer. During summer months, the trajectories present slow-moving (short) transport and are more locally influenced than in other seasons. Finally, our reanalysis trace element correlations suggest that marine derived trace element concentrations are strongly influenced by sea ice concentration and sea surface temperature anomalies. The results show that seasonal elemental concentration maxima in sea-salt elements correlate well with the sea ice concentration winter maxima in the West Amundsen and Ross Seas. Lastly, we observed an increased concentration of marine aerosols when sea surface temperature decreased.

scholarly journals A 125-year record of climate and chemistry variability at the Pine Island Glacier ice divide, Antarctica

2017 ◽  
Vol 11 (4) ◽  
pp. 1537-1552 ◽  
Author(s):  
Franciele Schwanck ◽  
Jefferson C. Simões ◽  
Michael Handley ◽  
Paul A. Mayewski ◽  
Jeffrey D. Auger ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Trace Element ◽  
Ice Core ◽  
Sea Salt ◽  
Sea Surface ◽  
The West ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
Glacier Ice

Abstract. The Mount Johns (MJ) ice core (79°55′ S; 94°23′ W) was drilled near the Pine Island Glacier ice divide on the West Antarctic Ice Sheet during the 2008–2009 austral summer, to a depth of 92.26 m. The upper 45 m of the record covers approximately 125 years (1883–2008), showing marked seasonal variability. Trace element concentrations in 2137 samples were determined using inductively coupled plasma mass spectrometry. In this study, we reconstruct mineral dust and sea salt aerosol transport and investigate the influence of climate variables on the elemental concentrations at the MJ site. The ice core record reflects changes in emissions as well as atmospheric circulation and transport processes. Our trajectory analysis shows distinct seasonality, with strong westerly transport in the winter months and secondary northeasterly transport in the summer. During summer months, the trajectories present slow-moving (short) transport and are more locally influenced than in other seasons. Finally, our reanalysis correlations with trace element suggest that marine-derived trace element concentrations are strongly influenced by sea ice concentration and sea surface temperature anomalies. The results show that seasonal elemental concentration maxima in sea salt elements correlate well with the sea ice concentration winter maxima in the west Amundsen and Ross seas. Lastly, we observed an increased concentration of marine aerosols when sea surface temperature decreased.

scholarly journals Sea ice and large-scale atmospheric variability around East Antarctica

2021 ◽  
Author(s):  
◽  
Florence Isaacs
Keyword(s):  
Indian Ocean ◽  
Climate Variability ◽  
Sea Ice ◽  
Large Scale ◽  
Wave Train ◽  
East Antarctica ◽  
Sea Ice Concentration ◽  
Atmospheric Wave ◽  
Ice Concentration ◽  
Dronning Maud Land

<p><b>​​Antarctica’s sea ice cover is an important component in the global climate system. The variability and recent trends of sea ice concentration are, however, not accurately reproduced by models. Evaluating model performance is hampered because the processes that determine sea ice distribution are not yet well understood, particularly in the East Antarctic region. Here I explore the relationships between recent climate variability and sea ice around East Antarctica, the spatial variability in these relationships, and the impacts that these may have on other aspects of the climate and cryosphere. To achieve this, I analysed satellite-derived HadlSST sea ice concentration (SIC) alongside ERA5 atmospheric reanalysis data for the period between 1979-2018.</b></p> <p>I found that variability in sea ice coverage around East Antarctica was affected by El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), the Southern Annular Mode (SAM), and Zonal Wave 3 (ZW3). Additionally, I found that the influence of each of these modes varied spatially and temporally, and that sea ice variability affected how regional scale climate responded to changes in large-scale circulation. Summer and autumn SIC around Dronning Maud Land between 10°E and 70°E exhibited a statistically significant negative correlation with the Niño 3.4 index. Analysis of ERA5 data suggests that a southward‐propagating atmospheric wave train triggered by SST anomalies in the tropical Pacific extends into Dronning Maud Land and alters sea ice concentration by encouraging meridional airflow. Shifts in meridional flow in Dronning Maud Land affected sea ice thermodynamically, by altering local heat transport and in turn altering sea ice formation and melt. </p> <p>Sea ice around the Western Pacific sector (WPS) of East Antarctica showed a significant association with variability in the IOD and the SAM. The IOD was correlated with SIC in all seasons but summer. The IOD-SIC relationship is likely driven by an IOD-associated atmospheric wave-train which propagates polewards from the tropical Indian Ocean to Wilkes Land, altering regional circulation and in turn affecting SIC through changes to local climate and sea ice transport. The correlation between WPS SIC and the SAM shifts from positive in summer and autumn to negative in winter and spring, and is likely due to the influence of the SAM on katabatic winds and coastal polynyas, which in turn affect SIC. </p> <p>A significant correlation was observed between SIC variability around East Antarctica and precipitation variability across the continent and the near-coastal Southern Ocean. Further analysis showed that SIC affected how continental precipitation responded to large-scale atmospheric circulation, including modes such as ZW3 and the SAM. Specifically, increased southward moisture flux was only associated with increased precipitation in the inland coastal regions of the continent when SIC was anomalously low. These findings suggest that any future decrease in sea ice may result in greater coupling of climate variability with continental precipitation.</p>

scholarly journals DASSO: a data assimilation system for the Southern Ocean that utilizes both sea-ice concentration and thickness observations

2021 ◽  
pp. 1-6
Author(s):  
Hao Luo ◽  
Qinghua Yang ◽  
Longjiang Mu ◽  
Xiangshan Tian-Kunze ◽  
Lars Nerger ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Southern Ocean ◽  
Sea Ice ◽  
Coupled Model ◽  
Sea Ice Concentration ◽  
Model Free ◽  
Antarctic Sea Ice ◽  
Ice Concentration ◽  
Data Assimilation System ◽  
Assimilation System

Abstract To improve Antarctic sea-ice simulations and estimations, an ensemble-based Data Assimilation System for the Southern Ocean (DASSO) was developed based on a regional sea ice–ocean coupled model, which assimilates sea-ice thickness (SIT) together with sea-ice concentration (SIC) derived from satellites. To validate the performance of DASSO, experiments were conducted from 15 April to 14 October 2016. Generally, assimilating SIC and SIT can suppress the overestimation of sea ice in the model-free run. Besides considering uncertainties in the operational atmospheric forcing data, a covariance inflation procedure in data assimilation further improves the simulation of Antarctic sea ice, especially SIT. The results demonstrate the effectiveness of assimilating sea-ice observations in reconstructing the state of Antarctic sea ice, but also highlight the necessity of more reasonable error estimation for the background as well as the observation.

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