scholarly journals Seismic stratigraphy along the Amundsen Sea to Ross Sea continental rise: A cross-regional record of pre-glacial to glacial processes of the West Antarctic margin

2016 ◽  
Vol 443 ◽  
pp. 183-202 ◽  
Author(s):  
Ansa Lindeque ◽  
Karsten Gohl ◽  
Stuart Henrys ◽  
Florian Wobbe ◽  
Bryan Davy
Keyword(s):  
Ross Sea ◽  
Seismic Stratigraphy ◽  
The West ◽  
Amundsen Sea ◽  
Continental Rise ◽  
West Antarctic ◽  
Glacial Processes

scholarly journals Reconstructing atmospheric circulation and sea-ice extent in the West Antarctic over the past 200 years using data assimilation

2021 ◽  
Author(s):  
Quentin Dalaiden ◽  
Hugues Goosse ◽  
Jeanne Rezsohazy ◽  
Elizabeth R. Thomas
Keyword(s):  
Data Assimilation ◽  
Sea Ice ◽  
Ross Sea ◽  
Snow Accumulation ◽  
The West ◽  
Sea Ice Extent ◽  
Amundsen Sea ◽  
The Past ◽  
West Antarctic

Abstract The West Antarctic climate has witnessed large changes during the second half of the 20th century including a strong and widespread continental warming, important regional changes in sea-ice extent and snow accumulation, as well as a major mass loss from the melting of some ice shelves. However, the potential links between those observed changes are still unclear and instrumental data do not allow determination of whether they are part of a long-term evolution or specific to the recent decades. In this study, we analyze the climate variability of the past two centuries in the West Antarctic sector by reconstructing the key atmospheric variables (atmospheric circulation, near-surface air temperature and snow accumulation) as well as the sea-ice extent at the annual timescale using a data assimilation approach. To this end, information from Antarctic ice core records (snow accumulation and δ 18 O and tree-ring width records situated in the mid-latitudes of the Southern Hemisphere are combined with the physics of climate models using a data assimilation method. This ultimately provides a complete spatial reconstruction over the west Antarctic region. Our reconstruction reproduces well the main characteristics of the observed changes over the instrumental period. We show that the observed sea-ice reduction in the Bellingshausen-Amundsen Sea sector over the satellite era is part of a long-term trend, starting at around 1850 CE, while the sea-ice expansion in the Ross Sea sector has only started around 1950 CE. Furthermore, according to our reconstruction, the Amundsen Sea Low pressure (ASL) displays no significant linear trend in its strength or position over 1850--1950 CE but becomes stronger and shifts eastward afterwards. The year-to-year sea-ice variations in the Ross Sea sector are strongly related to the ASL variability over the past two centuries, including the recent trends. By contrast, the link between ASL and sea-ice in the Bellingshausen-Amundsen Sea sector changes with time, being stronger in recent decades than before. Our reconstruction also suggests that the continental response to the variability of the ASL may not be stationary over time, being significantly affected by modification of the mean circulation. Finally, we show that the widespread warming since 1958 CE in West Antarctica is unusual in the context of past 200 years and is explained by both the deeper ASL and the positive phase of the Southern Annular Mode.

scholarly journals Reconstructing atmospheric circulation and sea-ice extent in the West Antarctic over the past 200 years using data assimilation 

2021 ◽  
Author(s):  
Quentin Dalaiden ◽  
Hugues Goosse ◽  
Jeanne Rezsohazy ◽  
Elizabeth R. Thomas
Keyword(s):  
Data Assimilation ◽  
Sea Ice ◽  
Ross Sea ◽  
Snow Accumulation ◽  
The West ◽  
Sea Ice Extent ◽  
Amundsen Sea ◽  
The Past ◽  
West Antarctic

<p>Ocean and ice sheet in the West Antarctic sector have witnessed large climate changes during the second half of the 20<sup>th</sup> century including a strong and widespread continental warming, important regional changes in sea-ice extent and snow accumulation, as well as a major mass loss from the melting of some ice shelves. However, the potential links between those observed changes are still unclear and instrumental data do not allow determining if they are part of a long-term evolution or specific to the recent decades. In this study, we analyze the climate variability of the past two centuries in the West Antarctic sector by reconstructing the key atmospheric variables (atmospheric circulation, near-surface air temperature and snow accumulation) as well as the sea-ice extent at the annual timescale using a data assimilation approach. To this end, information from Antarctic ice core records (snow accumulation and δ<sup>18</sup>O) and tree-ring width sites located in the mid-latitudes of the Southern Hemisphere are combined with the physics of climate models using a data assimilation method. This ultimately provides a complete spatial reconstruction over the west Antarctic region. Our reconstruction reproduces well the main characteristics of the observed changes over the instrumental period. We show that the observed sea-ice reduction in the Bellingshausen-Amundsen Sea sector over the satellite era is part of a long-term trend, starting at around 1850 CE, while the sea-ice expansion in the Ross Sea sector has only started around 1950 CE. Furthermore, according to our reconstruction, the Amundsen Sea Low pressure (ASL) displays no significant linear trend in its strength or position over 1850-1950 CE but becomes stronger and shifts eastward afterwards. The year-to-year sea-ice variations in the Ross Sea sector are strongly related to the ASL variability over the past two centuries, including the recent trends. By contrast, the link between ASL and sea ice the Bellingshausen-Amundsen Sea sector changes with time, being stronger in recent decades than before, Our reconstruction also suggests that the continental response to the variability of the ASL may not be stationary over time, being significantly affected by modification of the mean circulation. Finally, we show that the widespread warming since 1958 CE in West Antarctica is unusual in the context of past 200 years and is explained by both the deeper ASL and the positive phase of the Southern Annular Mode.</p>

scholarly journals New insights from multi-proxy data from the West Antarctic continental rise: Implications for dating and interpreting Late Quaternary palaeoenvironmental records

2021 ◽  
Vol 257 ◽  
pp. 106842
Author(s):  
C.-D. Hillenbrand ◽  
S.J. Crowhurst ◽  
M. Williams ◽  
D.A. Hodell ◽  
I.N. McCave ◽  
...  
Keyword(s):  
Late Quaternary ◽  
The West ◽  
Proxy Data ◽  
Continental Rise ◽  
West Antarctic

scholarly journals The Amundsen Sea Low: Variability, Change, and Impact on Antarctic Climate

2016 ◽  
Vol 97 (1) ◽  
pp. 111-121 ◽  
Author(s):  
M. N. Raphael ◽  
G. J. Marshall ◽  
J. Turner ◽  
R. L. Fogt ◽  
D. Schneider ◽  
...  
Keyword(s):  
Sea Ice ◽  
Climate Model ◽  
Ross Sea ◽  
Ice Core ◽  
Meridional Wind ◽  
West Antarctica ◽  
Sea Ice Extent ◽  
Amundsen Sea ◽  
West Antarctic ◽  
Climate Model Simulations

Abstract The Amundsen Sea low (ASL) is a climatological low pressure center that exerts considerable influence on the climate of West Antarctica. Its potential to explain important recent changes in Antarctic climate, for example, in temperature and sea ice extent, means that it has become the focus of an increasing number of studies. Here, the authors summarize the current understanding of the ASL, using reanalysis datasets to analyze recent variability and trends, as well as ice-core chemistry and climate model projections, to examine past and future changes in the ASL, respectively. The ASL has deepened in recent decades, affecting the climate through its influence on the regional meridional wind field, which controls the advection of moisture and heat into the continent. Deepening of the ASL in spring is consistent with observed West Antarctic warming and greater sea ice extent in the Ross Sea. Climate model simulations for recent decades indicate that this deepening is mediated by tropical variability while climate model projections through the twenty-first century suggest that the ASL will deepen in some seasons in response to greenhouse gas concentration increases.

Active subglacial volcanism in West Antarctica as assessed by airborne geophysics: Distribution and context

2020 ◽  
Author(s):  
Donald Blankenship ◽  
Enrica Quatini ◽  
Duncan Young
Keyword(s):  
Ice Sheet ◽  
Ice Cores ◽  
Rift System ◽  
West Antarctica ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Subglacial Volcanism

<p>A combination of aerogeophysics, seismic observations and direct observation from ice cores and subglacial sampling has revealed at least 21 sites under the West Antarctic Ice sheet consistent with active volcanism (where active is defined as volcanism that has interacted with the current manifestation of the West Antarctic Ice Sheet). Coverage of these datasets is heterogenous, potentially biasing the apparent distribution of these features. Also, the products of volcanic activity under thinner ice characterized by relatively fast flow are more prone to erosion and removal by the ice sheet, and therefore potentially underrepresented. Unsurprisingly, the sites of active subglacial volcanism we have identified often overlap with areas of relatively thick ice and slow ice surface flow, both of which are critical conditions for the preservation of volcanic records. Overall, we find the majority of active subglacial volcanic sites in West Antarctica concentrate strongly along the crustal thickness gradients bounding the central West Antarctic Rift System, complemented by intra-rift sites associated with the Amundsen Sea to Siple Coast lithospheric transition.</p>

scholarly journals Variability of accumulation rate in the catchments of Ice Streams B, C, D and E, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 227-230 ◽  
Author(s):  
E. R. Venteris ◽  
I. M. Whillans
Keyword(s):  
Measurement Error ◽  
Spatial Variation ◽  
Time Variation ◽  
Ross Sea ◽  
Accumulation Rate ◽  
Ice Streams ◽  
The West ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Uncertainty Model

A model of error and variability in snow arrumulation rate is formulated to determine the reliability of accumulation-rate point measurements as regional and temporal means. The uncertainty model is applied to data from 70 shallow firn cores covering the Ross Sea drainage of the West Antarctic ice sheet. The model includes measurement error, local spatial variation and time variation. Average uncertainly in accumulation rate is 0.016maice equivalent or about 15%. Considering that measurement and depositional uncertainties are independent from core-to-core, an uncertainty of 0.01 m a−1 applies when many values are used to integrate accumulation rate over a catchment.

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