ALBERT

Description: Abstract: We present here a high resolution (0.11 m) dataset of the isotopic composition of the ice (δ¹⁸O) from the EPICA Dome-C ice core. The dataset covers the depth range 7.81-3189.89 m (0.05-802.427 ka). Analysis is performed in Copenhagen with a CO~2~ equilibration Mass Spectrometry system (Finnegan MAT 251). Samples of 5 ml are equilibrated with CO~2~ for 6 hours under vibrations, thereafter injected to the mass spectrometer where the ¹⁸O/¹⁶O ratio is obtained on masses 46 and 44. All measurements reported on the SMOW-SLAP scale using a 2-point linear calibration (standards used: Crete: -33.61 ‰ and DC02: -54.11 ‰ . The combined uncertainty of the record is 0.07 ‰. We interpolate the dataset on the AICC2012 chronology.

Description: A continuous high-resolution record of digital images was obtained from the North Greenland Ice Core Project (NGRIP) ice core in the depth interval from 1330 m to the bedrock at 3085 m during the Greenland field seasons of 2000 and 2001. The images are obtained as dark-field images from an indirect light source and provide detailed visual documentation of the ice core at high depth resolution. The visual stratigraphy grey-scale intensity profile (the line-scan profile) is obtained as an averaged intensity profile from the centre part of the stratigraphy images along the direction of the core. The dataset covers the depth interval 1371.15-2425.00 m in 1 mm depth resolution and with grey scale values in the range of 0-255. The profile is unprocessed and includes all core breaks that give rise high intensity values that should be regarded as contamination. Furthermore, the profile suffers from an intensity saturation issue that is uncorrected for. Finally, the section 1371.15–1750 m depth is hampered by ice relaxation effects as this section of the core was overwintering in Greenland for one year prior to analysis. The dataset was applied to construct the glacial part of the GICC05 ice-core chronology. The analytical technique and the intensity profile are described in Svensson et al. (2005).

Description: ECM data of the DYE-3 cores obtained with the technique described by Hammer (1980). People involved in the measurements include Henrik B. Clausen, Dorthe Dahl-Jensen, Niels Gundestrup and Steffen B. Hansen, Jakob Schwander, and J.P. Steffensen. Data were originally recorded on paper in high resolution but was digitized by hand in 1 cm resolution by laboratory assistant Anita Boas. The data set includes data from the DYE-3 main core and from two shallow cores, known as 4B and 18C, drilled upstream of the main drilling site. Main core: Drilled to bedrock 1979-1981 during the GISP program. Position: 65.18N, 43.83W, 2480 m a.s.l.. Core 4B: Drilled to 174 m 8 km upstream from DYE-3. Exact position not available. Core 18C: Drilled to 110 m 36 km upstream from DYE-3. Position 65.03N 44.39W. The data are given as H^+ ion concentration versus depth (measured from the undisturbed surface at the year where drilling started), but the absolute calibration must be considered tentative. For more information on the measurements and calibration, see Hammer 1980. Please cite the Hammer (1980), Neftel et al. (1985), and Rasmussen et al. (2023) when using this data file.

Description: ECM data from the GRIP core obtained with the technique described by Hammer (1980). People involved in the measurements include Henrik B. Clausen, Dorthe Dahl-Jensen, Christine Hvidberg, Niels Gundestrup, Steffen B. Hansen, P. M. Kristinsdottir, Jakob Schwander, and J.P. Steffensen. Data were recorded in parallel on paper in high resolution and digitally in 1 cm resolution. The main core was drilled during the GRIP project in 1989-1992 at the Summit of the Greenland ice sheet. The length is 3025 m. Present-day accumulation 0.23 m ice/yr. Data from the top 101.3 m comes from the S3 shallow core, but the two data sets have been fully integrated on a common depth scale. The data are given as H+ ion concentration versus depth (measured from the undisturbed surface in 1989), but the absolute calibration (H+ = 0.045 I^1.73) must be considered tentative. For more information on the measurements and calibration, see Hammer 1980 and Clausen et al. (1995). Please cite the Hammer (1980), Clausen et al. (1995), and Rasmussen et al. (2023) when using this data file.

Description: ECM data of the DYE-3 cores obtained with the technique described by Hammer (1980). People involved in the measurements include Henrik B. Clausen, Dorthe Dahl-Jensen, Niels Gundestrup and Steffen B. Hansen, Jakob Schwander, and J.P. Steffensen. Data were originally recorded on paper in high resolution but was digitized by hand in 1 cm resolution by laboratory assistant Anita Boas. The data set includes data from the DYE-3 main core and from two shallow cores, known as 4B and 18C, drilled upstream of the main drilling site. Main core: Drilled to bedrock 1979-1981 during the GISP program. Position: 65.18N, 43.83W, 2480 m a.s.l.. Core 4B: Drilled to 174 m 8 km upstream from DYE-3. Exact position not available. Core 18C: Drilled to 110 m 36 km upstream from DYE-3. Position 65.03N 44.39W. The data are given as H^+ ion concentration versus depth (measured from the undisturbed surface at the year where drilling started), but the absolute calibration must be considered tentative. For more information on the measurements and calibration, see Hammer 1980. Please cite the Hammer (1980), Neftel et al. (1985), and Rasmussen et al. (2023) when using this data file.

Description: ECM data of the DYE-3 cores obtained with the technique described by Hammer (1980). People involved in the measurements include Henrik B. Clausen, Dorthe Dahl-Jensen, Niels Gundestrup and Steffen B. Hansen, Jakob Schwander, and J.P. Steffensen. Data were originally recorded on paper in high resolution but was digitized by hand in 1 cm resolution by laboratory assistant Anita Boas. Main core: Drilled to bedrock 1979-1981 during the GISP program. Position: 65.18N, 43.83W, 2480 m a.s.l.. Core 4B: Drilled to 174 m 8 km upstream from DYE-3. Exact position not available. Core 18C: Drilled to 110 m 36 km upstream from DYE-3. Position 65.03N 44.39W. The data are given as H^+ ion concentration versus depth (measured from the undisturbed surface at the year where drilling started), but the absolute calibration must be considered tentative. For more information on the measurements and calibration, see Hammer 1980. Please cite the Hammer (1980), Neftel et al. (1985), and Rasmussen et al. (2023) when using this data file.

Description: ECM data of the DYE-3 cores obtained with the technique described by Hammer (1980). People involved in the measurements include Henrik B. Clausen, Dorthe Dahl-Jensen, Niels Gundestrup and Steffen B. Hansen, Jakob Schwander, and J.P. Steffensen. Data were originally recorded on paper in high resolution but was digitized by hand in 1 cm resolution by laboratory assistant Anita Boas. The data set includes data from the DYE-3 main core and from two shallow cores, known as 4B and 18C, drilled upstream of the main drilling site. Main core: Drilled to bedrock 1979-1981 during the GISP program. Position: 65.18N, 43.83W, 2480 m a.s.l.. Core 4B: Drilled to 174 m 8 km upstream from DYE-3. Exact position not available. Core 18C: Drilled to 110 m 36 km upstream from DYE-3. Position 65.03N 44.39W. The data are given as H^+ ion concentration versus depth (measured from the undisturbed surface at the year where drilling started), but the absolute calibration must be considered tentative. For more information on the measurements and calibration, see Hammer 1980. Please cite the Hammer (1980), Neftel et al. (1985), and Rasmussen et al. (2023) when using this data file.

Description: We present here a high resolution water isotope (18O/16O, 2H/1H) record from the NEEM ice core covering the period 8 - 129 ky b2k. The depth resolution of the record is 0.05 m. The analysis has been performed using Cavity Ring Down Spectroscopy with an average precision for the whole record equal to 0.05 and 0.3 ‰ for δ18O and δD respectively. Measurements are calibrated and reported on the SMOW/SLAP scale using a 2-fixed-point calibration. Results are also reported on the GICC05 and AICC2012 timescale.

Description: Ion concentration data was obtained from the NGRIP1 ice core drilled in 1996 and 1997. NGRIP1 camp position 75.1N, 42.32W. All samples were cut and decontaminated using a microtome knife in a laminar-flow bench at the field site. In 1996, the 9.850 – 349.250 meter depth interval was cut continuously in 5 cm resolution. In 1997, selected sections from the Holocene, mainly containing volcanic signals, were cut in 5 cm or 2.5 cm depth resolution. Samples covering the 8.2 ka BP cold event were cut from the depth interval 1221-1237.5 m. The frozen samples were thawed in the laboratory and immediately after poured into sample vials for ion chromatography analyses. Bags 212-403 were measured in Department of Physical Geography, Stockholm University, Sweden. The rest of the samples were measured at the Geophysics Department, Niels Bohr Institute, University of Copenhagen, Denmark, on a Dionex 500 IC. The data are labeled "Sto" and "Cph" for samples analysed respectively in Stockholm and Copenhagen. Data measured in Stockholm were calibrated to a calibration curve established using eight standards, while data measured in Copenhagen were calibrated to a linear calibration curve established using a single standard. Ammonium concentrations measured in Copenhagen may be biased due to possible sample uptake of Ammonium from the air while in the liquid phase. In Stockholm, Li⁺ was not measured and F⁻ -concentrations may be biased due to methods that was not optimal for quantification of fast eluted ions. All values are ion concentrations given in µeq/L (micro-equivalent per liter melted ice). Data were collated November 2000 by Marie-Louise Siggaard-Andersen. Samples that are labeled PID (Possible Improper Decontamination) was marked in the field in cases where proper decontamination could be questioned. However, the amount of contamination is limited because the samples were in a solid state and the environment was very clean. Samples labeled PCL (Possible Contamination in the Liquid phase) was marked in the laboratory or during data evaluation in cases where contamination could be questioned. Samples labeled "remeasured" have been measured from a portion of the sample that has been kept in liquid state for several hours after thawing. The organic acids, formic acid and acetic acid, were measured but not quantified. A few sample are labeled "Organic Acid" because significant large amounts was observed in the chromatograms. The data file is released in connection with the ESSD paper of Rasmussen et al. (2023). Information about analysis setup can be found in Littot et al. (2002), Siggaard-Andersen et al. (2002), and Jonsell et al., (2007).

Description: Insoluble particles in ice cores record signatures of past climate parameters like vegetation dynamics, volcanic activity, and aridity. For some of them, the analytical detection relies on intensive bench microscopy investigation and requires dedicated sample preparation steps. Both are laborious, require in-depth knowledge, and often restrict sampling strategies. To help overcome these limitations, we present a framework based on flow imaging microscopy coupled to a deep neural network for autonomous image classification of ice core particles. We train the network to classify seven commonly found classes, namely mineral dust, felsic and mafic (basaltic) volcanic ash grains (tephra), three species of pollen (Corylus avellana, Quercus robur, Quercus suber), and contamination particles that may be introduced onto the ice core surface during core handling operations. The trained network achieves 96.8% classification accuracy at test time. We present the system’s potential and its limitations with respect to the detection of mineral dust, pollen grains, and tephra shards, using both controlled materials and real ice core samples. The methodology requires little sample material, is nondestructive, fully reproducible, and does not require any sample preparation procedures. The presented framework can bolster research in the field by cutting down processing time, supporting human-operated microscopy, and further unlocking the paleoclimate potential of ice core records by providing the opportunity to identify an array of ice core particles. Suggestions for an improved system to be deployed within a continuous flow analysis workflow are also presented.

Description: Published

Description: 539-565

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal