The SP19 chronology for the South Pole Ice Core – Part 1: volcanic matching and annual layer counting

Winski, D.; Fudge, T. J.; Ferris, D. G.; Osterberg, E. C.; Fegyveresi, John M.; Cole‐Dai, Jihong; Thundercloud, Zayta; Cox, Thomas S.; Kreutz, K. J.; Ortman, Nikolas; Buizert, Christo; Epifanio, Jenna; Brook, Edward J.; Beaudette, Ross; Severinghaus, Jeffrey P.; Sowers, Todd; Steig, Eric J.; Kahle, Emma C.; Jones, Tyler R.; Morris, Valerie; Aydın, Murat; Nicewonger, M. R.; Casey, Kimberly A.; Alley, Richard B.; Waddington, Edwin D.; Iverson, Nels; Dunbar, Nelia W.; Bay, R.; Souney, Joseph M.; Sigl, Michael; McConnell, Joseph R.

doi:10.5194/cp-15-1793-2019

Cited by 51 publications

(75 citation statements)

References 87 publications

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“…Accumulation measurements from snow pits and shallow firn cores are sparse (Favier et al, 2013;Picciotto et al, 1971). The survey area is in a region of low snow accumulation (7-10 cm annual water equivalent) (Arthern et al, 2006;McConnell et al, 1997;Mosley-Thompson et al, 1999;Winski et al, 2019) and low surface slope (0.11 • ± 0.10 • , Fig. A1a) (Helm et al, 2014a).…”

Section: Data Sets and Survey Areamentioning

confidence: 99%

Temporal and spatial variability in surface roughness and accumulation rate around 88° S from repeat airborne geophysical surveys

et al. 2020

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Abstract. We use repeat high-resolution airborne geophysical data consisting of laser altimetry, snow, and Ku-band radar and optical imagery acquired in 2014, 2016, and 2017 to analyze the spatial and temporal variability in surface roughness, slope, wind deposition, and snow accumulation at 88∘ S, an elevation bias validation site for ICESat-2 and potential validation site for CryoSat-2. We find significant small-scale variability (<10 km) in snow accumulation based on the snow radar subsurface stratigraphy, indicating areas of strong wind redistribution are prevalent at 88∘ S. In general, highs in snow accumulation rate correspond with topographic lows, resulting in a negative correlation coefficient of r2=-0.32 between accumulation rate and MSWD (mean slope in the mean wind direction). This relationship is strongest in areas where the dominant wind direction is parallel to the survey profile, which is expected as the geophysical surveys only capture a two-dimensional cross section of snow redistribution. Variability in snow accumulation appears to correlate with variability in MSWD. The correlation coefficient between the standard deviations of accumulation rate and MSWD is r2=0.48, indicating a stronger link between the standard deviations than the actual parameters. Our analysis shows that there is no simple relationship between surface slope, wind direction, and snow accumulation rates for the overall survey area. We find high variability in surface roughness derived from laser altimetry measurements on length scales smaller than 10 km, sometimes with very distinct and sharp transitions. Some areas also show significant temporal variability over the course of the 3 survey years. Ultimately, there is no statistically significant slope-independent relationship between surface roughness and accumulation rates within our survey area. The observed correspondence between the small-scale temporal and spatial variability in surface roughness and backscatter, as evidenced by Ku-band radar signal strength retrievals, will make it difficult to develop elevation bias corrections for radar altimeter retrieval algorithms.

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Section: Data Sets and Survey Areamentioning

confidence: 99%

Temporal and spatial variability in surface roughness and accumulation rate around 88° S from repeat airborne geophysical surveys

et al. 2020

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“…The superscripts 17, 18, D refer to δ 17 O, δ 18 O, δD, and the subscripts L2130, L2140 to the instrument used. All calculations were made on 250-year windows of the 0.5 cm high-resolution calibrated data, using the ice timescale of (Winski et al, 2019). σ from δ 17 O recalculated for the L2130 (Eq.…”

Section: Resultsmentioning

confidence: 99%

“…The modern accumulation rate at South Pole is 8 cm w. e. yr −1 (Casey et al, 2014), and the mean annual temperature is −51°C (Severinghaus et al, 2001). A depth-age relationship for the core, tied directly to the timescale for the WAIS Divide ice core (WAIS Divide Project Members, 2013; WAIS Divide Project Members, 2015), was developed by Winski et al (2019) and is termed the "SP19" chronology. A timescale for the gas within the core is also available (Epifanio et al, 2020).…”

Section: Ice Core Samplesmentioning

confidence: 99%

“…In principle these data could be also used to independently verify laboratory-based measurements of isotopic diffusivity, which remain uncertain (Hellmann and Harvey, 2020). Figure 9 shows the δ 18 O, deuterium excess and Δ 17 O, averaged to 100-years resolution, from the South Pole ice core, on the timescale from Winski et al (2019). We include both the conventional linear deuterium excess (d, Eq.…”

Section: Isotope Records From the South Pole Ice Corementioning

confidence: 99%

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Continuous-Flow Analysis of δ17O, δ18O, and δD of H2O on an Ice Core from the South Pole

et al. 2021

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The δD and δ18O values of water are key measurements in polar ice-core research, owing to their strong and well-understood relationship with local temperature. Deuterium excess, d, the deviation from the average linear relationship between δD and δ18O, is also commonly used to provide information about the oceanic moisture sources where polar precipitation originates. Measurements of δ17O and “17O excess” (Δ17O) are also of interest because of their potential to provide information complementary to d. Such measurements are challenging because of the greater precision required, particularly for Δ17O. Here, high-precision measurements are reported for δ17O, δ18O, and δD on a new ice core from the South Pole, using a continuous-flow measurement system coupled to two cavity ring-down laser spectroscopy instruments. Replicate measurements show that at 0.5 cm resolution, external precision is ∼0.2‰ for δ17O and δ18O, and ∼1‰ for δD. For Δ17O, achieving external precision of <0.01‰ requires depth averages of ∼50 cm. The resulting ∼54,000-year record of the complete oxygen and hydrogen isotope ratios from the South Pole ice core is discussed. The time series of Δ17O variations from the South Pole shows significant millennial-scale variability, and is correlated with the logarithmic formulation of deuterium excess (dln), but not the traditional linear formulation (d).

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“…wheret is the age in steady state, d depth, a accumulation, H ice thickness, and h the kink height below which horizontal deformation is concentrated. This model is simple, but has a long history of successful application to ice-core glaciology (e.g., Dansgaard and Johnsen, 1969;Dahl-Jensen et al, 1999;Winski et al, 2019). As in Parrenin et al (2017), we used a temporally variable accumulation rate, and solved for the depth-age using a pseudo-steady method which permits analytical solutions even with the temporally variable accumulation (Parrenin et al, 2006).…”

Section: Depth-age At the Beldc Sitementioning

confidence: 99%

Brief Communication: New radar constraints support presence of ice older than 1.5 Ma at Little Dome C

Lilien¹,

Steinhage²,

Taylor³

et al. 2020

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Abstract. The area near Dome C, East Antarctica, is thought to be one of the most promising targets for recovering a continuous ice-core record spanning more than a million years. The European Beyond EPICA consortium has selected Little Dome C, an area ~35 km south-east of Concordia Station, to attempt to recover such a record. Here, we present the results of the final ice-penetrating radar survey used to refine the exact drill site. These data were acquired during the 2019–2020 Austral summer using a new, multi-channel high-resolution VHF radar operating in the frequency range of 170–230 MHz. This new instrument is able to detect reflections in the near-basal region, where previous surveys were unable to trace continuous horizons. The radar stratigraphy is used to transfer the timescale of the EPICA Dome C ice core (EDC) to the area of Little Dome C, using radar isochrones dating back past 600 ka. We use these data to derive the expected depth–age relationship through the ice column at the now-chosen drill site, termed BELDC. These new data indicate that the ice at BELDC is considerably older than that at EDC at the same depth, and that there is about 375 m of ice older than 600 ka at BELDC. Stratigraphy is well preserved to 2565 m, below which there is a basal unit with unknown properties. A simple ice flow model tuned to the isochrones suggests ages likely reach 1.5 Ma near 2525 m, ~40 m above the basal unit and ~240 m above the bed, with sufficient resolution (14±1 ka m−1) to resolve 41 ka glacial cycles.

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The SP19 chronology for the South Pole Ice Core – Part 1: volcanic matching and annual layer counting

Cited by 51 publications

References 87 publications

Temporal and spatial variability in surface roughness and accumulation rate around 88° S from repeat airborne geophysical surveys

Temporal and spatial variability in surface roughness and accumulation rate around 88° S from repeat airborne geophysical surveys

Continuous-Flow Analysis of δ17O, δ18O, and δD of H2O on an Ice Core from the South Pole

Brief Communication: New radar constraints support presence of ice older than 1.5 Ma at Little Dome C

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