Inferring palaeo-accumulation records from ice-core data by an adjoint-based method: application to James Ross Island's ice core

Abstract. Ice cores contain a record of snow precipitation that includes information about past atmospheric circulation and mass imbalance in the polar regions. We present a novel approach to reconstruct a climatic record – by both optimally dating an ice core and deriving from it a detailed accumulation history – that uses an adjoint-based method. The motivation of our work is the recent application of phase-sensitive radar which measures the vertical velocity of an ice column. The velocity is dependent on the history of subsequent snow accumulation, compaction and compression; in our inverse formulation of this problem, measured vertical velocity profiles can be utilized directly, thereby reducing the uncertainty introduced by ice-flow modelling. We first apply our method to synthetic data in order to study its capability and the effect of noise and gaps in the age–depth observations. The method is then applied to the ice core retrieved from James Ross Island, Antarctica. We show that the method is robust and that the results depend on the quality of the age–depth observations and the derived flow regime around the core site. The method facilitates the incorporation of increasing detail provided by ice-core analysis together with observed full-depth velocity in order to construct a complete climatic record of the polar regions.

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Inferring paleo-accumulation records from ice-core data by an adjoint method: application to James Ross Island's ice core

Climate of the Past Discussions ◽

10.5194/cpd-10-3821-2014 ◽

2014 ◽

Vol 10 (5) ◽

pp. 3821-3845 ◽

Cited By ~ 1

Author(s):

C. Martín ◽

R. Mulvaney ◽

G. H. Gudmundsson ◽

H. Corr

Keyword(s):

Vertical Velocity ◽

Adjoint Method ◽

Ice Core ◽

Synthetic Data ◽

Ice Cores ◽

Snow Accumulation ◽

Polar Regions ◽

History Of ◽

Climatic Record ◽

Accumulation History

Abstract. Ice cores contain a record of snow precipitation that includes information about past atmospheric circulation and mass imbalance in the polar regions. We present a novel adjoint method to reconstruct a climatic record by both optimally dating an ice-core and deriving from it a detailed accumulation history. The motivation of our work is the recent application of phase sensitive radar which measures the vertical velocity of an ice column. The velocity is dependent on the history of subsequent snow accumulation, compaction and compression; and in our inverse formulation of this problem, measured vertical velocity profiles can be utilized directly thereby reducing the uncertainty introduced by ice flow modelling. We first apply our method to synthetic data in order to study its capability and the effect of noise and gaps in the data on retrieved accumulation history. The method is then applied to the ice core retrieved from James Ross Island, Antarctica. We show that the method is robust and that the results depend on quality of the age-depth observations and the derived flow regime around the core site. The method facilitates the incorporation of increasing detail provided by ice-core analysis together with observed full-depth velocity in order to construct a complete climatic record of the polar regions.

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Variability of black carbon deposition to the East Antarctic Plateau, AD 1800–2000

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-31091-2011 ◽

2011 ◽

Vol 11 (11) ◽

pp. 31091-31114 ◽

Cited By ~ 2

Author(s):

M. M. Bisiaux ◽

R. Edwards ◽

J. R. McConnell ◽

M. R. Albert ◽

H. Anschütz ◽

...

Keyword(s):

Black Carbon ◽

Geometric Mean ◽

Ice Core ◽

Ice Sheet ◽

Ice Cores ◽

Snow Accumulation ◽

Antarctic Ice Sheet ◽

Decadal Scale ◽

History Of ◽

Aerosol Emissions

Abstract. Refractory black carbon aerosols (rBC) from biomass burning and fossil fuel combustion are deposited to the Antarctic ice sheet and preserve a history of emissions and long-range transport from low latitudes. Antarctic ice core rBC records may thus provide information with respect to past combustion aerosol emissions and atmospheric circulation. Here, we present six East Antarctic ice core records of rBC concentrations and fluxes covering the last two centuries with approximately annual resolution (cal. yr. 1800 to 2000). The ice cores were drilled in disparate regions of the high East Antarctic ice sheet, at different elevations and net snow accumulation rates. Annual rBC concentrations were log-normally distributed and geometric means of annual concentrations ranged from 0.10 to 0.18 μg kg−1. Average rBC fluxes were determined over the time periods 1800 to 2000 and 1963 to 2000 and ranged from 3.4 to 15.5 μg kg−1 m−2 a−1 and 3.6 to 21.8 μg kg−1 m−2 a−1 respectively. Geometric-mean concentrations spanning 1800 to 2000 increased linearly with elevation at a rate of 0.025 μg kg−1/500 m. Spectral analysis of the records revealed significant decadal scale variability, which at several sites was comparable to decadal ENSO variability.

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Variability of black carbon deposition to the East Antarctic Plateau, 1800–2000 AD

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-3799-2012 ◽

2012 ◽

Vol 12 (8) ◽

pp. 3799-3808 ◽

Cited By ~ 29

Author(s):

M. M. Bisiaux ◽

R. Edwards ◽

J. R. McConnell ◽

M. R. Albert ◽

H. Anschütz ◽

...

Keyword(s):

Black Carbon ◽

Geometric Mean ◽

Ice Core ◽

Ice Sheet ◽

Ice Cores ◽

Snow Accumulation ◽

Antarctic Ice Sheet ◽

Decadal Scale ◽

History Of ◽

Aerosol Emissions

Abstract. Refractory black carbon aerosols (rBC) from biomass burning and fossil fuel combustion are deposited to the Antarctic ice sheet and preserve a history of emissions and long-range transport from low- and mid-latitudes. Antarctic ice core rBC records may thus provide information with respect to past combustion aerosol emissions and atmospheric circulation. Here, we present six East Antarctic ice core records of rBC concentrations and fluxes covering the last two centuries with approximately annual resolution (cal. yr. 1800 to 2000). The ice cores were drilled in disparate regions of the high East Antarctic ice sheet, at different elevations and net snow accumulation rates. Annual rBC concentrations were log-normally distributed and geometric means of annual concentrations ranged from 0.10 to 0.18 μg kg−1. Average rBC fluxes were determined over the time periods 1800 to 2000 and 1963 to 2000 and ranged from 3.4 to 15.5 μg m−2 a−1 and 3.6 to 21.8 μg m−2 a−1, respectively. Geometric mean concentrations spanning 1800 to 2000 increased linearly with elevation at a rate of 0.025 μg kg−1/500 m. Spectral analysis of the records revealed significant decadal-scale variability, which at several sites was comparable to decadal ENSO variability.

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Reconstructing Antarctic snow accumulation using nitrogen isotopes of nitrate

10.5194/egusphere-egu21-672 ◽

2021 ◽

Author(s):

Pete D. Akers ◽

Joël Savarino ◽

Nicolas Caillon ◽

Mark Curran ◽

Tas Van Ommen

Keyword(s):

Nitrogen Isotopes ◽

Full Range ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

East Antarctica ◽

Accumulation Rates ◽

Sea Levels ◽

Antarctic Snow ◽

Parallel Reconstruction

Precise Antarctic snow accumulation estimates are needed to understand past and future changes in global sea levels, but standard reconstructions using water isotopes suffer from competing isotopic effects external to accumulation. We present here an alternative accumulation proxy based on the post-depositional photolytic fractionation of nitrogen isotopes (d15N) in nitrate. On the high plateau of East Antarctica, sunlight penetrating the uppermost snow layers converts snow-borne nitrate into nitrogen oxide gas that can be lost to the atmosphere. This nitrate loss favors 14NO3- over 15NO3-, and thus the d15N of nitrate remaining in the snow will steadily increase until the nitrate is eventually buried beneath the reach of light. Because the duration of time until burial is dependent upon the rate of net snow accumulation, sites with lower accumulation rates have a longer burial wait and thus higher d15N values. A linear relationship (r2 = 0.86) between d15N and net accumulation-1 is calculated from over 120 samples representing 105 sites spanning East Antarctica. These sites largely encompass the full range of snow accumulation rates observed in East Antarctica, from 25 kg m-2 yr-1 at deep interior sites to >400 kg m-2 yr-1 at near coastal sites. We apply this relationship as a transfer function to an Aurora Basin ice core to produce a 700-year record of accumulation changes. Our nitrate-based estimate compares very well with a parallel reconstruction for Aurora Basin that uses volcanic horizons and ice-penetrating radar. Continued improvements to our database may enable precise independent estimates of millennial-scale accumulation changes using deep ice cores such as EPICA Dome C and Beyond EPICA-Oldest Ice.

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Glaciological Investigations of the Tropical Quelccaya Ice Cap, Peru

Journal of Glaciology ◽

10.3189/s0022143000010297 ◽

1980 ◽

Vol 25 (91) ◽

pp. 69-84 ◽

Cited By ~ 7

Author(s):

Lonnie G. Thompson

Keyword(s):

Rainy Season ◽

Ice Core ◽

Ice Cores ◽

Dry Season ◽

Radioactive Material ◽

Polar Regions ◽

Near Surface ◽

Ice Cap ◽

Activity Measurements ◽

Quelccaya Ice Cap

AbstractGlaciological results of the continuing investigations of the Quelccaya ice cap located at lat. 13° 56’ S., long. 70° 50’ W., in the Cordillera Oriental of southern Peru are presented. Ice cores to a depth of 15 m have been retrieved from the summit dome (5650 m), middle dome (5543 m), and south dome (5480 m) and sampled in detail for microparticle, oxygen-isotope, and total-β-activity measurements. Results of these core analyses indicate that although the summit of this ice cap is only 300 m above the annual snow line and the firn is temperate, an interpretable stratigraphic record is preserved. The marked seasonal ice stratigraphy is produced by the marked seasonal variation in regional precipitation. High concentrations of microparticles and β- radioactive material occur during the dry season (May-August). Microparticles deposited during the rainy season are larger than those deposited during the dry season. On the Quelccaya ice cap the most negative δ18O values occur during the warmer rainy season (the opposite occurs in polar regions). The near-surface mean δ value of – 21‰ is remarkably low for this tropical site where the measured mean annual air temperature is – 3°C The seasonality of the microparticles, total β activity, and isotope ratios offers the prospect of a climatic ice-core record from this tropical ice cap.

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Climatic and atmospheric circulation pattern variability from ice-core isotope/geochemistry records (Altai, Tien Shan and Tibet)

Annals of Glaciology ◽

10.3189/172756406781812078 ◽

2006 ◽

Vol 43 ◽

pp. 49-60 ◽

Cited By ~ 87

Author(s):

Vladimir B. Aizen ◽

Elena M. Aizen ◽

Daniel R. Joswiak ◽

Koji Fujita ◽

Nozomu Takeuchi ◽

...

Keyword(s):

Air Temperature ◽

Isotope Geochemistry ◽

Eastern Mediterranean ◽

Meteorological Data ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Tien Shan ◽

Synoptic Climatology ◽

The Tibetan Plateau

AbstractSeveral firn/ice cores were recovered from the Siberian Altai (Belukha plateau), central Tien Shan (Inilchek glacier) and the Tibetan Plateau (Zuoqiupu glacier, Bomi) from 1998 to 2003. The comparison analyses of stable-isotope/geochemistry records obtained from these firn/ice cores identified the physical links controlling the climate-related signals at the seasonal-scale variability. The core data related to physical stratigraphy, meteorology and synoptic atmospheric dynamics were the basis for calibration, validation and clustering of the relationships between the firn-/ice-core isotope/ geochemistry and snow accumulation, air temperature and precipitation origin. The mean annual accumulation (in water equivalent) was 106 gcm−2 a−1 at Inilchek glacier, 69 gcm−2 a−1 at Belukha and 196 g cm−2 a−1 at Zuoqiupu. The slopes in regression lines between the δ18O ice-core records and air temperature were found to be positive for the Tien Shan and Altai glaciers and negative for southeastern Tibet, where heavy amounts of isotopically depleted precipitation occur during summer monsoons. The technique of coupling synoptic climatology and meteorological data with δ18O and d-excess in firn-core records was developed to determine climate-related signals and to identify the origin of moisture. In Altai, two-thirds of accumulation from 1984 to 2001 was formed from oceanic precipitation, and the rest of the precipitation was recycled over Aral–Caspian sources. In the Tien Shan, 87% of snow accumulation forms by precipitation originating from the Aral–Caspian closed basin, the eastern Mediterranean and Black Seas, and 13% from the North Atlantic.

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The Anthropogenic Impact on Snow Chemistry at Colle Gnifetti, Swiss Alps

Annals of Glaciology ◽

10.3189/s0260305500004407 ◽

1988 ◽

Vol 10 ◽

pp. 183-187 ◽

Cited By ~ 6

Author(s):

D. Wagenbach ◽

K.O. Münnich ◽

U. Schotterer ◽

H. Oeschger

Keyword(s):

Chemical Analysis ◽

Ice Core ◽

Ice Cores ◽

Summer Precipitation ◽

Snow Accumulation ◽

Swiss Alps ◽

Saharan Dust ◽

Water Conductivity ◽

Air Masses ◽

Melt Water

By chemical analysis of the upper 40 m of a 124 m ice core from a high-altitude Alpine glacier (Colle Gnifetti, Swiss Alps; 4450 m a.s.l.), records of mineral dust, pH, melt-water conductivity, nitrate and sulfate are obtained. The characteristics of the drilling site are discussed, as derived from glacio-meteorological and chemical analysis. As a consequence of high snow-erosion rates (usually during the winter months), annual snow accumulation is dominated by summer precipitation. Clean-air conditions prevail even during summer; however, they are frequently interrupted by polluted air masses or by air masses which are heavily loaded with desert dust.Absolutely dated reference horizons for Saharan dust, together with the position of the broad nuclear-weapon tritium peak, provide the time-scale for the following statements:(1) Since at least the turn of the century the background melt-water conductivity has been rising steadily, as has the mean snow acidity. The trend of increasing background conductivity at Colle Gnifetti (1.9μS/cm around the beginning of this century, and at present 3.4 μS/cm) is found to be comparable with the records of mean melt-water conductivity reported from ice cores from the Canadian High Arctic.(2) Sulfate and nitrate concentrations are higher by a factor of 4–5 than they were at the beginning of the century. This is to be compared with the two- to three-fold rise in the concentrations in south Greenland during about the same time span.

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The Anthropogenic Impact on Snow Chemistry at Colle Gnifetti, Swiss Alps

Annals of Glaciology ◽

10.1017/s0260305500004407 ◽

1988 ◽

Vol 10 ◽

pp. 183-187 ◽

Cited By ~ 62

Author(s):

D. Wagenbach ◽

K.O. Münnich ◽

U. Schotterer ◽

H. Oeschger

Keyword(s):

Chemical Analysis ◽

Ice Core ◽

Ice Cores ◽

Summer Precipitation ◽

Snow Accumulation ◽

Swiss Alps ◽

Saharan Dust ◽

Water Conductivity ◽

Air Masses ◽

Melt Water

By chemical analysis of the upper 40 m of a 124 m ice core from a high-altitude Alpine glacier (Colle Gnifetti, Swiss Alps; 4450 m a.s.l.), records of mineral dust, pH, melt-water conductivity, nitrate and sulfate are obtained. The characteristics of the drilling site are discussed, as derived from glacio-meteorological and chemical analysis. As a consequence of high snow-erosion rates (usually during the winter months), annual snow accumulation is dominated by summer precipitation. Clean-air conditions prevail even during summer; however, they are frequently interrupted by polluted air masses or by air masses which are heavily loaded with desert dust. Absolutely dated reference horizons for Saharan dust, together with the position of the broad nuclear-weapon tritium peak, provide the time-scale for the following statements: (1) Since at least the turn of the century the background melt-water conductivity has been rising steadily, as has the mean snow acidity. The trend of increasing background conductivity at Colle Gnifetti (1.9μS/cm around the beginning of this century, and at present 3.4 μS/cm) is found to be comparable with the records of mean melt-water conductivity reported from ice cores from the Canadian High Arctic. (2) Sulfate and nitrate concentrations are higher by a factor of 4–5 than they were at the beginning of the century. This is to be compared with the two- to three-fold rise in the concentrations in south Greenland during about the same time span.

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History of desert dust deposition recorded in the Elbrus ice core

10.5194/acp-2019-411 ◽

2019 ◽

Author(s):

Stanislav Kutuzov ◽

Michel Legrand ◽

Suzanne Preunkert ◽

Patrick Ginot ◽

Vladimir Mikhalenko ◽

...

Keyword(s):

North Africa ◽

Drought Index ◽

Decadal Variability ◽

Ice Core ◽

Ice Cores ◽

Dust Deposition ◽

The Past ◽

Dust Sources ◽

Increasing Trend ◽

History Of

Abstract. Ice cores are one of the most valuable paleo-archives. Records from the ice cores can provide information not only about the amount of dust in the atmosphere but also about dust sources and its changes in the past. A 182 m long ice core has been recovered at the western plateau of Mt. Elbrus (5115 m elevation) in 2009. This record was extended with the shallow ice core drilling in 2013. Here we present analysis of the concentrations of Ca2+, a commonly used proxy of dust, recorded in Elbrus ice core over the period 1774–2013. The calcium record reveals a quasi decadal variability with a general increasing trend. Using multiple regression analysis we found a statistically significant spatial correlation of the Elbrus Ca2+ summer concentrations and precipitation and soil moisture content in Levant region (specifically Syria and Iraq). The Ca2+ record also correlates with drought index in North Africa (r = 0.69 p

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1000 year ice-core records from Berkner Island, Antarctica

Annals of Glaciology ◽

10.3189/172756402781817176 ◽

2002 ◽

Vol 35 ◽

pp. 45-51 ◽

Cited By ~ 39

Author(s):

Robert Mulvaney ◽

Hans Oerter ◽

David A. Peel ◽

Wolfgang Graf ◽

Carol Arrowsmith ◽

...

Keyword(s):

Decadal Variability ◽

Ice Core ◽

Ice Cores ◽

Aerosol Deposition ◽

Climate History ◽

Joint Project ◽

The Past ◽

Annual Layer ◽

History Of ◽

Field Season

AbstractTwo medium-depth ice cores were retrieved from Berkner Island by a joint project between the Alfred-Wegener-Institut and the British Antarctic Survey in the 1994/95 field season. A 151m deep core from the northern dome (Reinwarthhöhe) of Berkner Island spans 700 years, while a 181 m deep core from the southern dome (Thyssenhöhe) spans approximately 1200 years. Both cores display clear seasonal cycles in electrical conductivity measurements, allowing dating by annual-layer counting and the calculation of accumulation profiles. Stable-isotope measurements (both δ18O and δD), together with the accumulation data, allow us to estimate changes in climate for most of the past millennium: the data show multi-decadal variability around a generally stable long-termmean. In addition, a full suite of major chemistry measurements is available to define the history of aerosol deposition at these sites: again, there is little evidence that the chemistry of the sites has changed over the past six centuries. Finally, we suggest that the southern dome, with an ice thickness of 950 m, is an ideal site from which to gain a climate history of the late stages of the last glacial and the deglaciation for comparison with the records from the deep Antarctic ice cores, and with other intermediate-depth cores such as Taylor Dome and Siple Dome.

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