Investigation of the 18O Content of a 100 m Ice Core From the Ronne Ice Shelf, Antarctica

A 100 m ice core from the Ronne Ice Shelf, drilled during the 1983-84 field season, was dated by isotopic stratigraphy, using the well-known seasonal variation in the 18O content in firn and ice; the layers at a depth of 89 m are probably 400 years old. Layer thicknesses deduced from the 18O profile indicate short-term variations of the snow-accumulation rate over the last 400 years. The area of deposition of the material recovered with the core is estimated by a two-dimensional flow model and by the 18O content of the core, which decreases from –27.5‰ in the upper part of the core to –32.0‰ at 89 m depth.

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The EDC3 chronology for the EPICA Dome C ice core

Climate of the Past ◽

10.5194/cp-3-485-2007 ◽

2007 ◽

Vol 3 (3) ◽

pp. 485-497 ◽

Cited By ~ 316

Author(s):

F. Parrenin ◽

J.-M. Barnola ◽

J. Beer ◽

T. Blunier ◽

E. Castellano ◽

...

Keyword(s):

Pattern Matching ◽

Time Scales ◽

Excellent Agreement ◽

Time Scale ◽

Flow Model ◽

Ice Core ◽

Snow Accumulation ◽

The Core ◽

Time Periods ◽

Paleoclimatic Records

Abstract. The EPICA (European Project for Ice Coring in Antarctica) Dome C drilling in East Antarctica has now been completed to a depth of 3260 m, at only a few meters above bedrock. Here we present the new EDC3 chronology, which is based on the use of 1) a snow accumulation and mechanical flow model, and 2) a set of independent age markers along the core. These are obtained by pattern matching of recorded parameters to either absolutely dated paleoclimatic records, or to insolation variations. We show that this new time scale is in excellent agreement with the Dome Fuji and Vostok ice core time scales back to 100 kyr within 1 kyr. Discrepancies larger than 3 kyr arise during MIS 5.4, 5.5 and 6, which points to anomalies in either snow accumulation or mechanical flow during these time periods. We estimate that EDC3 gives accurate event durations within 20% (2σ) back to MIS11 and accurate absolute ages with a maximum uncertainty of 6 kyr back to 800 kyr.

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A 2700-year annual timescale and accumulation history for an ice core from Roosevelt Island, West Antarctica

Climate of the Past ◽

10.5194/cp-15-751-2019 ◽

2019 ◽

Vol 15 (2) ◽

pp. 751-779 ◽

Cited By ~ 9

Author(s):

Mai Winstrup ◽

Paul Vallelonga ◽

Helle A. Kjær ◽

Tyler J. Fudge ◽

James E. Lee ◽

...

Keyword(s):

Sea Ice ◽

Accumulation Rate ◽

Ice Core ◽

Snow Accumulation ◽

Accumulation Rates ◽

West Antarctica ◽

Sea Ice Extent ◽

Amundsen Sea ◽

The Core ◽

Accumulation History

Abstract. We present a 2700-year annually resolved chronology and snow accumulation history for the Roosevelt Island Climate Evolution (RICE) ice core, Ross Ice Shelf, West Antarctica. The core adds information on past accumulation changes in an otherwise poorly constrained sector of Antarctica. The timescale was constructed by identifying annual cycles in high-resolution impurity records, and it constitutes the top part of the Roosevelt Island Ice Core Chronology 2017 (RICE17). Validation by volcanic and methane matching to the WD2014 chronology from the WAIS Divide ice core shows that the two timescales are in excellent agreement. In a companion paper, gas matching to WAIS Divide is used to extend the timescale for the deeper part of the core in which annual layers cannot be identified. Based on the annually resolved timescale, we produced a record of past snow accumulation at Roosevelt Island. The accumulation history shows that Roosevelt Island experienced slightly increasing accumulation rates between 700 BCE and 1300 CE, with an average accumulation of 0.25±0.02 m water equivalent (w.e.) per year. Since 1300 CE, trends in the accumulation rate have been consistently negative, with an acceleration in the rate of decline after the mid-17th century. The current accumulation rate at Roosevelt Island is 0.210±0.002 m w.e. yr−1 (average since 1965 CE, ±2σ), and it is rapidly declining with a trend corresponding to 0.8 mm yr−2. The decline observed since the mid-1960s is 8 times faster than the long-term decreasing trend taking place over the previous centuries, with decadal mean accumulation rates consistently being below average. Previous research has shown a strong link between Roosevelt Island accumulation rates and the location and intensity of the Amundsen Sea Low, which has a significant impact on regional sea-ice extent. The decrease in accumulation rates at Roosevelt Island may therefore be explained in terms of a recent strengthening of the ASL and the expansion of sea ice in the eastern Ross Sea. The start of the rapid decrease in RICE accumulation rates observed in 1965 CE may thus mark the onset of significant increases in regional sea-ice extent.

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200 years of isotope and chemical records in a firn core from Hercules Névé, northern Victoria Land, Antarctica

Annals of Glaciology ◽

10.3189/172756499781821175 ◽

1999 ◽

Vol 29 ◽

pp. 106-112 ◽

Cited By ~ 17

Author(s):

B. Stenni ◽

R. Caprioli ◽

L. Cimino ◽

C. Cremisini ◽

O. Flora ◽

...

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Volcanic Eruptions ◽

Snow Accumulation ◽

The Core ◽

Victoria Land ◽

Chemical Profiles ◽

The 19Th Century ◽

Calculated Average ◽

Firn Core

AbstractA 42.2 m firn core was collected at the Hercules Névé plateau (100 km inland and 2960 m a.s.L), northern Victoria Land, during the 1994-95 Italian Antarctic Expedition. Chemical (Cl–, NO3–, SO42–’; δ18O δ18O δ18O; m-2a-1) and isotope (5180) analyses were performed to evaluate the snow-accumulation rate at this site. Tritium measurements were performed in the upper part of the core to narrow down the dating of the core.High nssSO42- concentrations seem to be related to some explosive volcanic eruptions, such as Tambora (AD 1815) and the preceding event called "Unknown" (AD 1809), Coseguina (AD 1835), Makjan (AD 1861), Krakatoa (AD 1883) and Tarawera (AD 1886).A comparison between the seasonal variations observed in the isotope and chemical profiles was carried out in order to reduce the dating uncertainty, using the tritium and the volcanic markers as time constraints. A deposition period of 222 years was determined.The 3 year smoothed «5180 profile shows more negative values from the bottom of the core (dated AD 1770) throughout the 19th century, suggesting "cooler" conditions, in agreement with other East Antarctic ice-core records! Subsequently, a general increase in δ180-values is observed.The calculated average snow-accumulation rates between the above-mentioned time markers are 111-129 kg m-2a-1.

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Accumulation and Ice-Core Studies on Filchner-Ronne Ice Shelf, Antarctica

Annals of Glaciology ◽

10.1017/s0260305500006273 ◽

1988 ◽

Vol 11 ◽

pp. 23-31 ◽

Cited By ~ 16

Author(s):

W. Graf

Keyword(s):

Flow Model ◽

Accumulation Rate ◽

Ice Core ◽

Ice Shelf ◽

Surface Layers ◽

Ice Flow ◽

Measuring Point ◽

Near Surface ◽

Ice Edge ◽

Drilling Site

Accumulation rates in the eastern part of Ronne Ice Shelf were determined by isotopic stratigraphy (18O). The samples were taken from snow-pits dug during the Filchner I and II operations in 1984 and 1986. In general, the accumulation rate decreases towards the south; the greatest decrease, from 21.3 to 13.3 g cm−2 a−1, was observed between Filchner Station and measuring point 341, sited 270 km up-stream of the ice edge. The δ18O values of the near-surface layers vary between −25 and -29‰. The 18O content in the more southerly part is progressively depleted in the direction of Möllereisstrom, paralleling a decrease in the accumulation rate. Near the ice edge the 18O content decreases to the west. A 100 m ice core drilled in 1984 at point 340, 220 km from the ice edge, probably goes back to A.D. 1460; it has been dated by isotopic stratigraphy. The accumulation rate up-stream of the drilling site was deduced from the sequence of annual layers, using a simple ice-flow model. The accumulation shows strong variations over the last 200 years, which may be caused in part by local variations in the accumulation on Ronne Ice Shelf.

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Dating of an East Antarctic ice core (GV7) by high resolution chemical stratigraphies

10.5194/cp-2021-44 ◽

2021 ◽

Author(s):

Raffaello Nardin ◽

Mirko Severi ◽

Alessandra Amore ◽

Silvia Becagli ◽

Francois Burgay ◽

...

Keyword(s):

Environmental Changes ◽

18Th Century ◽

Accumulation Rate ◽

Ice Core ◽

Methanesulfonic Acid ◽

Oxygen Isotopic Composition ◽

Snow Accumulation ◽

Sea Salt ◽

The Core ◽

History Of

Abstract. Ice core dating is the first step for a correct interpretation of climatic and environmental changes. In this work, we release a stratigraphic dating of the uppermost 197 m of the 250 m deep GV7(B) ice core (drilling site, 70°41’S, 158°52’E, 1950 m a.s.l.) with a sub-annual resolution. Chemical stratigraphies of NO3−, MSA (methanesulfonic acid), non-sea salt SO42−, sea-salt ions and the oxygen isotopic composition (δ18O) were used in the annual layer counting upon the identification of a seasonal profile in their records. Different procedures were tested and thanks to the volcanic history of the core, obtained in previous works, an accurate age-depth correlation was obtained for the period 1179–2009 CE. Once the dating of the core was finalized, the annual mean accumulation rate was evaluated throughout the analyzed 197 m of the core, obtaining an annually resolved history of the snow accumulation on site in the last millennium. A small, yet consistent, rise in accumulation rate was found for the last 830 years since the middle of the 18th century.

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The EDC3 chronology for the EPICA Dome C ice core

Climate of the Past Discussions ◽

10.5194/cpd-3-575-2007 ◽

2007 ◽

Vol 3 (2) ◽

pp. 575-606 ◽

Cited By ~ 12

Author(s):

F. Parrenin ◽

J.-M. Barnola ◽

J. Beer ◽

T. Blunier ◽

E. Castellano ◽

...

Keyword(s):

Pattern Matching ◽

Time Scales ◽

Excellent Agreement ◽

Time Scale ◽

Flow Model ◽

Ice Core ◽

Snow Accumulation ◽

The Core ◽

Time Periods ◽

Paleoclimatic Records

Abstract. The EPICA (European Project for Ice Coring in Antarctica) Dome C drilling in East Antarctica has now been completed to a depth of 3260 m, at only a few meters above bedrock. Here we present the new official EDC3 chronology, which is based on the use of 1) a snow accumulation and mechanical flow model, and 2) a set of independent age markers along the core. These are obtained by pattern matching of recorded parameters to either absolutely dated paleoclimatic records, or to insolation variations. We show that this new time scale is in excellent agreement with the Dome Fuji and Vostok ice core time scales back to 100 kyr within 1 kyr. Discrepancies larger than 3 kyr arise during MIS 5.4, 5.5 and 6, which points to anomalies in either snow accumulation or mechanical flow during these time periods. We estimate that EDC3 gives accurate event durations within 20% (2σ ) back to MIS11 and accurate absolute ages with a maximum uncertainty of 6 kyr back to 800 kyr.

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Accumulation and Ice-Core Studies on Filchner-Ronne Ice Shelf, Antarctica

Annals of Glaciology ◽

10.3189/s0260305500006273 ◽

1988 ◽

Vol 11 ◽

pp. 23-31 ◽

Cited By ~ 3

Author(s):

W. Graf ◽

H. Moser ◽

H. Oerter ◽

O. Reinwarth ◽

W. Stichler

Keyword(s):

Flow Model ◽

Accumulation Rate ◽

Ice Core ◽

Ice Shelf ◽

Surface Layers ◽

Ice Flow ◽

Measuring Point ◽

Near Surface ◽

Ice Edge ◽

Drilling Site

Accumulation rates in the eastern part of Ronne Ice Shelf were determined by isotopic stratigraphy (18O). The samples were taken from snow-pits dug during the Filchner I and II operations in 1984 and 1986. In general, the accumulation rate decreases towards the south; the greatest decrease, from 21.3 to 13.3 g cm−2 a−1, was observed between Filchner Station and measuring point 341, sited 270 km up-stream of the ice edge. The δ18O values of the near-surface layers vary between −25 and -29‰. The 18O content in the more southerly part is progressively depleted in the direction of Möllereisstrom, paralleling a decrease in the accumulation rate. Near the ice edge the 18O content decreases to the west. A 100 m ice core drilled in 1984 at point 340, 220 km from the ice edge, probably goes back to A.D. 1460; it has been dated by isotopic stratigraphy.The accumulation rate up-stream of the drilling site was deduced from the sequence of annual layers, using a simple ice-flow model. The accumulation shows strong variations over the last 200 years, which may be caused in part by local variations in the accumulation on Ronne Ice Shelf.

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A two-dimensional flow model of laser supported combustion waves

10.2514/6.1983-1718 ◽

1983 ◽

Author(s):

V. KULKARNY ◽

J. SHWARTZ ◽

S. FINK

Keyword(s):

Flow Model ◽

Two Dimensional ◽

Combustion Waves ◽

Dimensional Flow ◽

Two Dimensional Flow

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An Evaluation of the Average Flow Model [1] for Surface Roughness Effects in Lubrication

Journal of Lubrication Technology ◽

10.1115/1.3251544 ◽

1980 ◽

Vol 102 (3) ◽

pp. 360-366 ◽

Cited By ~ 23

Author(s):

J. L. Teale ◽

A. O. Lebeck

Keyword(s):

Surface Roughness ◽

Flow Model ◽

Two Dimensional ◽

Roughness Effects ◽

Important Conclusion ◽

Average Flow ◽

One Dimensional ◽

Dimensional Flow ◽

Two Dimensional Flow ◽

Average Flow Model

The average flow model presented by Patir and Cheng [1] is evaluated. First, it is shown that the choice of grid used in the average flow model influences the results. The results presented are different from those given by Patir and Cheng. Second, it is shown that the introduction of two-dimensional flow greatly reduces the effect of roughness on flow. Results based on one-dimensional flow cannot be relied upon for two-dimensional problems. Finally, some average flow factors are given for truncated rough surfaces. These can be applied to partially worn surfaces. The most important conclusion reached is that an even closer examination of the average flow concept is needed before the results can be applied with confidence to lubrication problems.

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