Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core.

ABSTRACT: Here we present the first direct comparison of cosmogenic (10)Be and chemical species in the period of 38-45.5 kyr BP spanning the Laschamp geomagnetic excursion from the EPICA-Dome C ice core. A principal component analysis (PCA) allowed to group different components as a function of the main sources, transport and deposition processes affecting the atmospheric aerosol at Dome C. Moreover, a wavelet analysis highlighted the high coherence and in-phase relationship between (10)Be and nitrate at this time. The evident preferential association of (10)Be with nitrate rather than with other chemical species was ascribed to the presence of a distinct source, here labelled as "cosmogenic". Both the PCA and wavelet analyses ruled out a significant role of calcium in driving the (10)Be and nitrate relationship, which is particularly relevant for a plateau site such as Dome C, especially in the glacial period during which the Laschamp excursion took place. The evidence that the nitrate record from the EDC ice core is able to capture the Laschamp event hints toward the possibility of using this marker for studying galactic cosmic ray flux variations and thus also major geomagnetic field excursions at pluri-centennial-millennial time scales, thus opening up new perspectives in paleoclimatic studies.

SUBMITTER: Traversi R

PROVIDER: S-EPMC4730186 | biostudies-other | 2016

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

East Greenland ice core dust record reveals timing of Greenland ice sheet advance and retreat.

Project description:Accurate estimates of the past extent of the Greenland ice sheet provide critical constraints for ice sheet models used to determine Greenland's response to climate forcing and contribution to global sea level. Here we use a continuous ice core dust record from the Renland ice cap on the east coast of Greenland to constrain the timing of changes to the ice sheet margin and relative sea level over the last glacial cycle. During the Holocene and the previous interglacial period (Eemian) the dust record was dominated by coarse particles consistent with rock samples from central East Greenland. From the coarse particle concentration record we infer the East Greenland ice sheet margin advanced from 113.4 ± 0.4 to 111.0 ± 0.4 ka BP during the glacial onset and retreated from 12.1 ± 0.1 to 9.0 ± 0.1 ka BP during the last deglaciation. These findings constrain the possible response of the Greenland ice sheet to climate forcings.

| S-EPMC6776541 | biostudies-literature

From the Cover: Antarctic climate signature in the Greenland ice core record.

Project description:A numerical algorithm is applied to the Greenland Ice Sheet Project 2 (GISP2) dust record from Greenland to remove the abrupt changes in dust flux associated with the Dansgaard-Oeschger (D-O) oscillations of the last glacial period. The procedure is based on the assumption that the rapid changes in dust are associated with large-scale changes in atmospheric transport and implies that D-O oscillations (in terms of their atmospheric imprint) are more symmetric in form than can be inferred from Greenland temperature records. After removal of the abrupt shifts the residual, dejumped dust record is found to match Antarctic climate variability with a temporal lag of several hundred years. It is argued that such variability may reflect changes in the source region of Greenland dust (thought to be the deserts of eastern Asia). Other records from this region and more globally also reveal Antarctic-style variability and suggest that this signal is globally pervasive. This provides the potential basis for suggesting a more important role for gradual changes in triggering more abrupt transitions in the climate system.

| S-EPMC2077246 | biostudies-literature

Greenland Ice Core Record of Last Glacial Dust Sources and Atmospheric Circulation.

Project description:Abrupt and large-scale climate changes have occurred repeatedly and within decades during the last glaciation. These events, where dramatic warming occurs over decades, are well represented in both Greenland ice core mineral dust and temperature records, suggesting a causal link. However, the feedbacks between atmospheric dust and climate change during these Dansgaard-Oeschger events are poorly known and the processes driving changes in atmospheric dust emission and transport remain elusive. Constraining dust provenance is key to resolving these gaps. Here, we present a multi-technique analysis of Greenland dust provenance using novel and established, source diagnostic isotopic tracers as well as results from a regional climate model including dust cycle simulations. We show that the existing dominant model for the provenance of Greenland dust as sourced from combined East Asian dust and Pacific volcanics is not supported. Rather, our clay mineralogical and Hf-Sr-Nd and D/H isotopic analyses from last glacial Greenland dust and an extensive range of Northern Hemisphere potential dust sources reveal three most likely scenarios (in order of probability): direct dust sourcing from the Taklimakan Desert in western China, direct sourcing from European glacial sources, or a mix of dust originating from Europe and North Africa. Furthermore, our regional climate modeling demonstrates the plausibility of European or mixed European/North African sources for the first time. We suggest that the origin of dust to Greenland is potentially more complex than previously recognized, demonstrating more uncertainty in our understanding dust climate feedbacks during abrupt events than previously understood.

| S-EPMC9542552 | biostudies-literature

Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change.

Project description:Nitrogen stable isotope ratio (?(15)N) in Greenland snow nitrate and in North American remote lake sediments has decreased gradually beginning as early as ?1850 Christian Era. This decrease was attributed to increasing atmospheric deposition of anthropogenic nitrate, reflecting an anthropogenic impact on the global nitrogen cycle, and the impact was thought to be amplified ?1970. However, our subannually resolved ice core records of ?(15)N and major ions (e.g., NO3(-), SO4(2-)) over the last ?200 y show that the decrease in ?(15)N is not always associated with increasing NO3(-) concentrations, and the decreasing trend actually leveled off ?1970. Correlation of ?(15)N with H(+), NO3(-), and HNO3 concentrations, combined with nitrogen isotope fractionation models, suggests that the ?(15)N decrease from ?1850-1970 was mainly caused by an anthropogenic-driven increase in atmospheric acidity through alteration of the gas-particle partitioning of atmospheric nitrate. The concentrations of NO3(-) and SO4(2-) also leveled off ?1970, reflecting the effect of air pollution mitigation strategies in North America on anthropogenic NO(x) and SO2 emissions. The consequent atmospheric acidity change, as reflected in the ice core record of H(+) concentrations, is likely responsible for the leveling off of ?(15)N ?1970, which, together with the leveling off of NO3(-) concentrations, suggests a regional mitigation of anthropogenic impact on the nitrogen cycle. Our results highlight the importance of atmospheric processes in controlling ?(15)N of nitrate and should be considered when using ?(15)N as a source indicator to study atmospheric flux of nitrate to land surface/ecosystems.

| S-EPMC4000786 | biostudies-other

Speleothem record of geomagnetic South Atlantic Anomaly recurrence.

Project description:The diminishing strength of the Earth's magnetic dipole over recent millennia is accompanied by the increasing prominence of the geomagnetic South Atlantic Anomaly (SAA), which spreads over the South Atlantic Ocean and South America. The longevity of this feature at millennial timescales is elusive because of the scarcity of continuous geomagnetic data for the region. Here, we report a unique geomagnetic record for the last ∼1500 y that combines the data of two well-dated stalagmites from Pau d'Alho cave, located close to the present-day minimum of the anomaly in central South America. Magnetic directions and relative paleointensity data for both stalagmites are generally consistent and agree with historical data from the last 500 y. Before 1500 CE, the data adhere to the geomagnetic model ARCH3K.1, which is derived solely from archeomagnetic data. Our observations indicate rapid directional variations (>0.1°/y) from approximately 860 to 960 CE and approximately 1450 to 1750 CE. A similar pattern of rapid directional variation observed from South Africa precedes the South American record by 224 ± 50 y. These results confirm that fast geomagnetic field variations linked to the SAA are a recurrent feature in the region. We develop synthetic models of reversed magnetic flux patches at the core-mantle boundary and calculate their expression at the Earth's surface. The models that qualitatively resemble the observational data involve westward (and southward) migration of midlatitude patches, combined with their expansion and intensification.

| S-EPMC6310861 | biostudies-other

Early-warning signals for Dansgaard-Oeschger events in a high-resolution ice core record.

Project description:The Dansgaard-Oeschger (DO) events, as observed in oxygen isotope ratios from the North Greenland Ice Core Project (NGRIP) record, are an outstanding example of past abrupt climate transitions. Their physical cause remains debated, and previous research indicated that they are not preceded by classical early-warning signals (EWS). Subsequent research hypothesized that the DO events are caused by bifurcations of physical mechanisms operating at decadal timescales, and proposed to search for EWS in the high-frequency fluctuation levels. Here, a time series with 5-year resolution is obtained from the raw NGRIP record, and significant numbers of EWS in terms of variance and autocorrelation increases are revealed in the decadal-scale variability. Wavelet analysis indicates that the EWS are most pronounced in the 10-50-year periodicity band, confirming the above hypothesis. The DO events are hence neither directly noise-induced nor purely externally forced, which provides valuable constraints regarding potential physical causes.

| S-EPMC6028441 | biostudies-literature

Geomagnetic spikes on the core-mantle boundary.

Project description:Extreme variations of Earth's magnetic field occurred in the Levant region around 1000 BC, when the field intensity rapidly rose and fell by a factor of 2. No coherent link currently exists between this intensity spike and the global field produced by the core geodynamo. Here we show that the Levantine spike must span >60° longitude at Earth's surface if it originates from the core-mantle boundary (CMB). Several low intensity data are incompatible with this geometric bound, though age uncertainties suggest these data could have sampled the field before the spike emerged. Models that best satisfy energetic and geometric constraints produce CMB spikes 8-22° wide, peaking at O(100) mT. We suggest that the Levantine spike reflects an intense CMB flux patch that grew in place before migrating northwest, contributing to growth of the dipole field. Estimates of Ohmic heating suggest that diffusive processes likely govern the ultimate decay of geomagnetic spikes.

| S-EPMC5459996 | biostudies-literature

Detecting dipolarity of the geomagnetic field in the paleomagnetic record.

Project description:Recovering the geomagnetic field strength in the past is key to understanding deep Earth dynamics and detecting potential geodynamo regimes throughout the history of Earth. To better constrain the predictive power of the paleomagnetic record, we propose an approach based on the analysis of the dependency between geomagnetic field strength and inclination (angle made by the horizontal with the field lines). Based on the outcomes of statistical field models, we show that these two quantities should correlate for a wide range of Earth-like magnetic fields, even with enhanced secular variation, persistent nonzonal components, and severe noise contamination. Focusing on the paleomagnetic record, we show that the correlation is not significant for the Brunhes polarity chron, what we ascribe to inadequate spatiotemporal sampling. In contrast, the correlation is significant for the 1 to 130 Ma interval, whereas it only marginally succeeds prior to 130 Ma when strict filters on both paleointensities and paleodirections are applied. As we cannot detect significant variations in the strength of the correlation over the 1 to 130 Ma interval, we conclude that the Cretaceous Normal Superchron may not be associated with enhanced dipolarity of the geodynamo. The strong correlation obtained prior to 130 Ma when strict filters are applied indicates that the ancient field may not be on average so different from the present-day field. If long-term fluctuations nevertheless existed, detecting potential geodynamo regimes during the Precambrian is currently impeded by the sparsity of high-quality data passing strict filters in both paleointensities and paleodirections.

| S-EPMC10288625 | biostudies-literature

A 120,000-year long climate record from a NW-Greenland deep ice core at ultra-high resolution.

Project description:We report high resolution measurements of the stable isotope ratios of ancient ice (δ18O, δD) from the North Greenland Eemian deep ice core (NEEM, 77.45° N, 51.06° E). The record covers the period 8-130 ky b2k (y before 2000) with a temporal resolution of ≈0.5 and 7 y at the top and the bottom of the core respectively and contains important climate events such as the 8.2 ky event, the last glacial termination and a series of glacial stadials and interstadials. At its bottom part the record contains ice from the Eemian interglacial. Isotope ratios are calibrated on the SMOW/SLAP scale and reported on the GICC05 (Greenland Ice Core Chronology 2005) and AICC2012 (Antarctic Ice Core Chronology 2012) time scales interpolated accordingly. We also provide estimates for measurement precision and accuracy for both δ18O and δD.

| S-EPMC8155095 | biostudies-literature

Core Surface Flow Changes Associated With the 2017 Pacific Geomagnetic Jerk.

Project description:A geomagnetic jerk was seen in Swarm satellite data in 2017 over the Pacific region. We invert time series of spatial gradient secular variation data between 2014 and 2020, reduced to a grid of points at satellite altitude, for spatially- and temporally-regularized core surface flow. Pacific region flow acceleration was almost constant before and after the jerk, with a sharp change, especially in the azimuthal component, at the jerk epoch, despite the temporal regularization. Azimuthal acceleration is oppositely signed either side of 160°W, where it effectively vanishes, and also reverses sign at the jerk epoch. Acceleration features drift westward at about 900 km year-1. Unlike previous studies, the evidence presented here for low latitude waves does not depend on imposing flow equatorial symmetry, quasi- or tangential geostrophy, or band-pass filtering, and has no reliance on stochastic models or numerical simulations.

| S-EPMC9539959 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data