ALBERT

Description: This is a dataset that has been acquired in 1995 as part of the U.S.-ROC Deep Seismic Imaging Study of the Taiwan Arc-Continent Collision (TAICRUST) project. This particular line was measured in the Taiwan Strait in September 1995 to image the shallow sediments and upper crust. Additional information from the Cruise EW9509 is stored at the Marine Geoscience Data System (MGDS).

Description: Transient simulations are widely used in studying the past climate as they provide better comparison with any exisiting proxy data. However, multi-millennial transient simulations using coupled climate models are usually computationally very expensive. As a result several acceleration techniques are implemented when using numerical simulations to recreate past climate. In this study, we compare the results from transient simulations of the present and the last interglacial with and without acceleration of the orbital forcing, using the comprehensive coupled climate model CCSM3 (Community Climate System Model 3). Our study shows that in low-latitude regions, the simulation of long-term variations in interglacial surface climate is not significantly affected by the use of the acceleration technique (with an acceleration factor of 10) and hence, large-scale model-data comparison of surface variables is not hampered. However, in high-latitude regions where the surface climate has a direct connection to the deep ocean, e.g. in the Southern Ocean or the Nordic Seas, acceleration-induced biases in sea-surface temperature evolution may occur with potential influence on the dynamics of the overlying atmosphere. The data provided here are from both accelerated and non-accelerated runs as decadal mean values.

Description: This entry contains two datasets from marine sediment core GeoB16204-2. While one dataset hosts geochemical (i.e., iron, titanium, calcium, ln(Fe/Ca), ln(Ti/Ca), calcium carbonate, total organic carbon, total nitrogen, stable hydrogen isotopic composition of C29 long-chain n-alkanes) and physical (i.e., porosity, wet bulk density, dry bulk density, fragmentation index, mass accumulation rate of the siliciclastic fraction and mass accumulation rate of the calcium carbonate fraction) data, the other hosts radiocarbon data.

Description: The Snow and Ice Mass Balance Array (SIMBA) is a thermistor string type IMB (Jackson et al., 2013) which measures the environment temperature SIMBA-ET and temperature change around the thermistors after a weak heating applied to each sensor (SIMBA-HT). Totally, there were 22 SIMBAs deployed in the Arcitic Ocean over the Distributed Network (DN) and the Central Observatory during the Legs 1a, 1 and 3 of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign. The SIMBA thermistor chain is 5.12 m long, and equipped with 256 thermistors (Maxim Integrated DS28EA00) at 0.02 m spacing. Based on a manual identification method, the SIMBA-ET and SIMBA-HT were processed to yield snow depth and ice thickness. Here, we combined the two optimal methods (the ET vertical gradient and HT rise ratio) to reduce the uncertainty. To keep the consistency, we use the snow or ice surface, consequentially the snow depth, determined by the ET vertical gradient. The formations of snow ice and superposed ice are not considered in this data set. That is to say, the value of snow depth includes the layers of snow ice at two sites (2019T56 and 2019T72). The superposed ice was generally negligible. We used the HT rise ratio to determine the ice-water interface, consequentially the ice thickness. Overall, the measurement accuracy was 0.02 m for both the snow depth and ice thickness. After the snow cover melted over, the negative values for the snow depth indicate the onset of ice surface melt. The submitted data package include 19 data files (for each buoy) and 1 buoy information file.

Description: By combining environmagnetic, geochemical, and siliciclastic grain size data, we investigated marine sediment core GL‐1090 (24.92°S, 42.51°W, 2225 m water depth) aiming to unravel changes in terrigenous sediment input and bottom water conditions during the last ∼184 ka at the western South Atlantic mid‐depth. This dataset contains: Clay/Silt ratio, Fe/kappa ratio, Magnetic Parameters (Anhysteretic remanent magnetization (ARM300), Isotermal Remanent Magnetization (IRM300) and Hard-IRM), S-Ratio, Volume Magnetic Suceptibility, xARM/IRM ratio and EDP-Calibrated XRF data from marine sediment core GL-1090.

Description: Marine sediment core GL-1248 was collected from the continental slope off northern northeastern Brazil by Petrobras oil company. Sediment samples (154 in total) were collected with 2 cm wide scoops at every 10 cm from the uppermost 16 m (covering the the last 113 thousand years) of the marine sediment core GL-1248. Samples were oven‐dried at 60°C, precisely weighted to 0.5 g and treated with H2O2 27% and HCl 10% to remove organic matter and calcium carbonate, respectively. The remaining content was diluted in alcohol and three aliquots per sample were mounted on stainless steel discs with four drops of the homogenized solution of alcohol and silt/clay sediments. GL-1248 luminescence measurements were performed on an automated Lexsyg Smart TL/OSL reader equipped with blue and infrared LEDs, Hoya U-340 filters for light detection in the ultraviolet band (270-390 nm) using a photomultiplier and beta radiation sources (90Sr/90Y) with doses rate of 0.116 Gy s-1 at the Luminescence and Gamma Spectrometry Laboratory of the Institute of Geosciences, University of São Paulo, Brazil. The sensitivity representative of the 110°C thermoluminesce (TL) peak of quartz considered the 80–120°C integration range from the TL curve. The 80-120°C TL sensitivity was calculated as a percentage of the total TL emission (0-250°C) and using the background TL curve. The mean of three measured aliquots represents the TL sensitivity of each sample. The OSL sensitivity was calculated by integrating the first second of light emission and the last ten seconds as background. GL-1248 TL sensitivity data were compared to previously published data obtained from marine sediment core GeoB16206-1 (https://doi.org/10.1594/PANGAEA.904357). Marine sediment core GeoB16206-1 was analyzed in a different luminescence reader (i.e. RisØ OSL/TL DA-20 reader) and using different regeneration dose. In order to avoid machine artifacts and the influence of dose size on sensitivity, we normalized the TL data output from both marine sediment cores and produced a composite record. Name of the Campaign: collected by the Petrobras oil company Event Label: GL1248 (GL-1248) Method: quarzt luminescence sensitivity Latitude: -0.920000 Longitude: -43.401667 Elevation: -2,264 m

Description: Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (d13C), i.e. d13CO2atm, presumably due to outgassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present d13C records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1 per mil) during Heinrich Stadials 3 and 2. These d13C decreases are most likely related to millennialscale periods of weakening of the Atlantic meridional overturning circulation and the consequent increase (decrease) in CO2atm (d13CO2atm). We hypothesise two mechanisms that could account for the decreases observed in our records, namely strengthening of Southern Ocean deep-water ventilation and weakening of the biological pump. Additionally, we suggest that air?sea gas exchange could have contributed to the observed d13C decreases. Together with other lines of evidence, our data are consistent with the hypothesis that the CO2 added to the atmosphere during abrupt millennial-scale climate change events of the last glacial period also originated in the ocean and reached the atmosphere by outgassing. The temporal evolution of d13C during Heinrich Stadials 3 and 2 in our records is characterized by two relative minima separated by a relative maximum. This ?w structure? is also found in North Atlantic and South American records, further suggesting that such a structure is a pervasive feature of Heinrich Stadial 2 and, possibly, also Heinrich Stadial 3.

Description: Data presented here were collected between January 2021 to December 2021 within the research unit DynaCom (Spatial community ecology in highly dynamic landscapes: From island biogeography to metaecosystems, https://uol.de/dynacom/ ) of the Universities of Oldenburg, Göttingen, and Münster, the iDiv Leipzig and the Nationalpark Niedersächsisches Wattenmeer. Experimental islands and saltmarsh enclosed plots were created in the back barrier tidal flat and in the saltmarsh zone of the island of Spiekeroog. Meteorological data were collected near the experimental setup, with a locally installed weather station located approximately 500m north of the southern shoreline. The weather station system used here was a ClimaSensor US 4.920x.00.00x that was pre-calibrated by the manufacturer (Adolf Thies GmbH & Co. KG, D-Göttingen). Data were recorded and saved within the Meteo-Online (V4.5.0.20253) software in a sampling interval of 1 min, with an averaging time of 10 s. Date and time were given in UTC and the position was derived from the internal GPS system. Data handling was performed according to Zielinski et al. (2018): Post-processing of collected data was done using MATLAB (R2018a). Quality control was performed by (a) erasing data covering maintenance activities, (b) removing outliers, defined as data exhibiting changes of more than two standard deviations within one time step, and (c) visually checks.

Description: The concentration of radiocarbon (14C) differs between ocean and atmosphere. Radiocarbon determinations from samples which obtained their 14C in the marine environment therefore need a marine-specific calibration curve and cannot be calibrated directly against the atmospheric-based IntCal20 curve. This paper presents Marine20, an update to the internationally-agreed marine radiocarbon age calibration curve that provides a non-polar global-average marine record of radiocarbon from 0 – 55 cal kBP and serves as a baseline for regional oceanic variation. Marine20 is based upon 500 simulations with an ocean/atmosphere/biosphere box-model of the global carbon cycle that has been forced by posterior realisations of our Northern Hemispheric atmospheric IntCal20 14C curve and reconstructed changes in CO2 obtained from ice core data. These forcings enable us to incorporate carbon cycle dynamics and temporal changes in the atmospheric 14C level. The box-model simulations of the global-average marine radiocarbon reservoir age are similar to those of a more complex three-dimensional ocean general circulation model. However, simplicity and speed of the box model allow us to use a Monte Carlo approach to rigorously propagate the uncertainty in both the historic concentration of atmospheric 14C and other key parameters of the carbon cycle through to our final Marine20 calibration curve. This robust propagation of uncertainty is fundamental to providing reliable precision for the radiocarbon age calibration of marine based samples. We make a first step towards deconvolving the contributions of different processes to the total uncertainty; discuss the main differences of Marine20 from the previous age calibration curve Marine13; and identify the limitations of our approach together with key areas for further work. The updated values for 𝛥𝑅, the regional marine radiocarbon reservoir age corrections required to calibrate against Marine20, can be found at the data base http://calib.org/marine/. This data set includes: - the data plotted in the related manuscript, including Marine20, and IntCal20, the most recent version of the radiocarbon age calibration curves - the 500 northern hemispheric atmospheric Δ14C realisations of IntCal20 used as input for the calculation of Marine20 - a netCDF file from the LSG OCGCM with spatially resolved marine reservoir ages.

Description: Negative excursions in the stable carbon isotopic composition (δ¹³C) at Atlantic intermediate to mid-depths are common features of millennial-scale events named Heinrich Stadials (HS). The mechanisms behind these excursions are not yet fully understood, but most hypotheses agree on the central role played by the weakening of the Atlantic meridional overturning circulation. Marine records registering millennial-scale negative δ¹³C excursions in the Atlantic are mostly restricted to the HS of the last deglacial, while the HS of the last glacial are poorly studied. Here we constrain changes in bottom water ventilation in the western tropical South Atlantic mid-depth during HS of the last glacial and deglacial by investigating marine core M125-95-3. The concurrent decreases in benthic foraminifera δ¹³C and increases in bulk sediment sulfur indicates an increased Northern Component Water (NCW) residence time in the western tropical South Atlantic mid-depth during HS. Furthermore, a coherent meridional pattern emerges from the comparison of our new data to previously published mid-depth records from the western South Atlantic. While our record shows the largest negative δ¹³C excursions during almost all HS, the western equatorial Atlantic showed medium and the subtropical South Atlantic showed the smallest negative excursions. This meridional pattern supports the notion that during HS a reduction in the NCW δ¹³C source signal together with the accumulation of respired carbon at NCW depths drove the negative δ¹³C excursions. We suggest that the negative δ¹³C excursions progressively increase along the NCW southwards pathway until the signal dissipates/dilutes by mixing with Southern Component Water.