Radionuclides deposition over Antarctica

Pourchet, M.; Magand, Olivier; Frezzotti, Màssimo; Ekaykin, A. A.; Winther, Jan‐Gunnar

doi:10.1016/s0265-931x(03)00055-9

Cited by 40 publications

(48 citation statements)

References 18 publications

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“…This is probably due to the fact that Arthern's accumulation map is based on available accumulation measurements. Between 200 and 500 km from DC, these correspond to data from Mulvaney and Wolff (1994) and Pourchet et al (2003), which display higher accumulation values than our own (Fig. 8).…”

Section: Spatial Variations In Accumulationsupporting

confidence: 79%

“…-Accumulation estimates made for the period 1955-1972 by Mulvaney and Wolff (1994) and Pourchet et al (2003) estimates. On the contrary, estimates by Mulvaney and Wolff (1994) and Pettré et al (1986) for the periods 1959-1969 and 1955-1980, respectively, are in good agreement with our results.…”

Section: Spatial Variations In Accumulationmentioning

confidence: 99%

“…Results were compared with historical data in the region (Pettré et al, 1986;Mulvaney and Wolff, 1994;Pourchet et al, 2003;Frezzotti et al, 2004;Urbini et al, 2008) and to four SMB climatologies (Arthern et al, 2006;van de Berg et al, 2006, ERAInterim and LMDZ4). We focused on the pre-industrial to the industrial period, which spans the last 300 yr (approximately the top 70 m of snow, or the first 750 ns of the radargrams).…”

Section: Introductionmentioning

confidence: 99%

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Snow accumulation variability derived from radar and firn core data along a 600 km transect in Adelie Land, East Antarctic plateau

et al. 2012

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Abstract. The mass balance of ice sheets is an intensively studied topic in the context of global change and sealevel rise. However -particularly in Antarctica -obtaining mass balance estimates remains difficult due to various logistical problems. In the framework of the TASTE-IDEA (Trans-Antarctic Scientific Traverses Expeditions -Ice Divide of East Antarctica) program, an International Polar Year project, continuous ground penetrating radar (GPR) measurements were carried out during a traverse in Adelie Land (East Antarctica) during the 2008-2009 austral summer between the Italian-French Dome C (DC) polar plateau site and French Dumont D'Urville (DdU) coastal station. The aim of this study was to process and interpret GPR data in terms of snow accumulation, to analyse its spatial and temporal variability and compare it with historical data and modelling. The focus was on the last 300 yr, from the preindustrial period to recent times. Beta-radioactivity counting and gamma spectrometry were applied to cores at the LGGE laboratory, providing a depth-age calibration for radar measurements. Over the 600 km of usable GPR data, depth and snow accumulation were determined with the help of three distinct layers visible on the radargrams (≈ 1730(≈ , 1799(≈ and 1941. Preliminary results reveal a gradual increase in accumulation towards the coast (from ≈ 3 cm w.e. a −1 at Dome C to ≈ 17 cm w.e. a −1 at the end of the transect) and previously undocumented undulating structures between 300 and 600 km from DC. Results agree fairly well with data from previous studies and modelling. Drawing final conclusions on temporal variations is difficult because of the margin of error introduced by density estimation. This study should have various applications, including model validation.

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Section: Spatial Variations In Accumulationsupporting

confidence: 79%

Section: Spatial Variations In Accumulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Snow accumulation variability derived from radar and firn core data along a 600 km transect in Adelie Land, East Antarctic plateau

et al. 2012

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“…The dates of arrival and deposition in this polar region are well known and therefore provide a means to estimate Antarctic snow accumulation rates or describe air mass circulation patterns (Pourchet et al, 2003;Magand, 2009, and references therein). The 1955 and 1965 CE radioactivity peaks provide two very convenient horizons for dating snow and firn layers and thus measuring accumulation.…”

Section: Artificial Radionuclides Deposition Over Antarctica and Assomentioning

confidence: 99%

Spatial and temporal distributions of surface mass balance between Concordia and Vostok stations, Antarctica, from combined radar and ice core data: first results and detailed error analysis

et al. 2018

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Abstract. Results from ground-penetrating radar (GPR) measurements and shallow ice cores carried out during a scientific traverse between Dome Concordia (DC) and Vostok stations are presented in order to infer both spatial and temporal characteristics of snow accumulation over the East Antarctic Plateau. Spatially continuous accumulation rates along the traverse are computed from the identification of three equally spaced radar reflections spanning about the last 600 years. Accurate dating of these internal reflection horizons (IRHs) is obtained from a depth–age relationship derived from volcanic horizons and bomb testing fallouts on a DC ice core and shows a very good consistency when tested against extra ice cores drilled along the radar profile. Accumulation rates are then inferred by accounting for density profiles down to each IRH. For the latter purpose, a careful error analysis showed that using a single and more accurate density profile along a DC core provided more reliable results than trying to include the potential spatial variability in density from extra (but less accurate) ice cores distributed along the profile. The most striking feature is an accumulation pattern that remains constant through time with persistent gradients such as a marked decrease from 26 mm w.e. yr−1 at DC to 20 mm w.e. yr−1 at the south-west end of the profile over the last 234 years on average (with a similar decrease from 25 to 19 mm w.e. yr−1 over the last 592 years). As for the time dependency, despite an overall consistency with similar measurements carried out along the main East Antarctic divides, interpreting possible trends remains difficult. Indeed, error bars in our measurements are still too large to unambiguously infer an apparent time increase in accumulation rate. For the proposed absolute values, maximum margins of error are in the range 4 mm w.e. yr−1 (last 234 years) to 2 mm w.e. yr−1 (last 592 years), a decrease with depth mainly resulting from the time-averaging when computing accumulation rates.

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“…In the Southern Hemisphere, the maximum fall out peaks of fission products ( 137 Cs; 241 Pu, indirectly measured by 241 Am; and 90 Sr) are clearly associated with the most intensive testing activity between 1961 to 1962, leading in the southern South America to subsequently fallout with the highest fluxes in 1964 and 1965 [Arnaud et al, 2006;Magand and Arnaud, 2007]. 241 Am is used to corroborate 137 Cs dates in case of possible disturbance of the 137 Cs profile [Appleby et al, 1991;Oldfield et al, 1995;Pourchet et al, 2003;Eisen et al, 2008].…”

Section: Radionuclides Speciesmentioning

confidence: 99%

A promising location in Patagonia for paleoclimate and paleoenvironmental reconstructions revealed by a shallow firn core from Monte San Valentín (Northern Patagonia Icefield, Chile)

et al. 2008

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International audienceThe study of past climate variability from ice core investigations has been largely developed both in polar areas over the past decades and, more recently, in tropical regions, specifically along the South American Andes between 0° and 20°S. However a large gap still remains at mid-latitudes in the Southern Hemisphere. In this framework, a 15.3-m long shallow firn core has been extracted in March 2005 from the summit plateau of Monte San Valentín (3747 m, 46°35′S, 73°19′W) in the Northern Patagonia Icefield to test its potential for paleoclimate and paleoenvironmental reconstructions. The firn temperature is −11.9°C at 10-m depth allowing to expect well preserved both chemical and isotopic signals, unperturbed by water percolation. The dating of the core, on the basis of a multi-proxy approach combining annual layer counting and radionuclide measurements, shows that past environment and climate can be reconstructed back to the mid-1960s. A mean annual snow accumulation rate of 36 ± 3 cm year−1 (i.e., 19 ± 2 g cm−2 year−1) is inferred, with a snow density varying between 0.35 and 0.6 g cm−3, which is much lower than accumulation rates previously reported in Patagonia at lower elevations. Here, we present and discuss high-resolution profiles of the isotopic composition of the snow and selected chemical markers. These data provide original information on environmental conditions prevailing over Southern Patagonia in terms of air masses trajectories and origins and biogeochemical reservoirs. Our main conclusion is that the San Valentín site is not only influenced by air masses originating from the southern Pacific and directly transported by the prevailing west winds but also by inputs from South American continental sources from the E–NE, sometimes mixed with circumpolar aged air masses, the relative influence of these two very distinct source areas changing at the interannual timescale. Thus this site should offer a wealth of information regarding (South) Pacific, Argentinian NE–E areas and Antarctic climate variability

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Radionuclides deposition over Antarctica

Cited by 40 publications

References 18 publications

Snow accumulation variability derived from radar and firn core data along a 600 km transect in Adelie Land, East Antarctic plateau

Snow accumulation variability derived from radar and firn core data along a 600 km transect in Adelie Land, East Antarctic plateau

Spatial and temporal distributions of surface mass balance between Concordia and Vostok stations, Antarctica, from combined radar and ice core data: first results and detailed error analysis

A promising location in Patagonia for paleoclimate and paleoenvironmental reconstructions revealed by a shallow firn core from Monte San Valentín (Northern Patagonia Icefield, Chile)

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