scholarly journals Anomaly Detection in Paleoclimate Records Using Permutation Entropy

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 931 ◽  
Author(s):  
Joshua Garland ◽  
Tyler Jones ◽  
Michael Neuder ◽  
Valerie Morris ◽  
James White ◽  
...  
Keyword(s):  
Ice Core ◽  
Field Work ◽  
Permutation Entropy ◽  
Post Processing ◽  
Polar Ice ◽  
Time Step ◽  
Laboratory Instrument ◽  
New Information ◽  
Paleoclimate Records ◽  
Advanced Version

Permutation entropy techniques can be useful for identifying anomalies in paleoclimate data records, including noise, outliers, and post-processing issues. We demonstrate this using weighted and unweighted permutation entropy with water-isotope records containing data from a deep polar ice core. In one region of these isotope records, our previous calculations (See Garland et al. 2018)revealed an abrupt change in the complexity of the traces: specifically, in the amount of new information that appeared at every time step. We conjectured that this effect was due to noise introduced by an older laboratory instrument. In this paper, we validate that conjecture by reanalyzing a section of the ice core using a more advanced version of the laboratory instrument. The anomalous noise levels are absent from the permutation entropy traces of the new data. In other sections of the core, we show that permutation entropy techniques can be used to identify anomalies in the data that are not associated with climatic or glaciological processes, but rather effects occurring during field work, laboratory analysis, or data post-processing. These examples make it clear that permutation entropy is a useful forensic tool for identifying sections of data that require targeted reanalysis—and can even be useful for guiding that analysis.

Information content in the rainfall observed by INSAT-3D and IMERG: An intercomparison study over the north eastern region of India

2021 ◽  
Author(s):  
Aniket Chakravorty ◽  
Shyam Sundar Kundu ◽  
Penumetcha Lakshmi Narasa Raju
Keyword(s):  
Information Content ◽  
Permutation Entropy ◽  
Eastern Region ◽  
Redundant Information ◽  
Time Step ◽  
Wavelet Entropy ◽  
Rainfall Prediction ◽  
The North ◽  
New Information ◽  
North Eastern

<p>There has been a noticeable increase in the application of artificial intelligence (AI) algorithms in various areas, in the recent past. One such area is the prediction of rainfall over a region. This application has seen crucial advancement with the use of deep sequential learning algorithms. This new approach to rainfall prediction has also helped increase the utilization of satellite data for prediction. As, AI based prediction algorithms are based on data, the characteristics of it dominates the accuracy of the prediction. And one such characteristic is the information content in the data being used. This information content is classified into redundant information (information of past states in the current state) and new information. The performance of the AI based rainfall prediction depends on the amount of redundant information present in the data being used for training the AI model, more the redundant information (less the new information content) more accurate will be the prediction. Various entropy based measure have been used to quantify the new information content in the data, like permutation entropy, sample entropy, wavelet entropy, etc. This study uses a new measure called the Wavelet Entropy Energy Measure (WEEM). One of the advantages of WEEM is that it considers the dynamics of the process spread across different time scales, which other information measures have not considered explicitly. Since, the dynamics of rainfall is multi-scalar in nature, WEEM is a suitable measure for it. The main goal of this study is to find out the amount of information being generated by INSAT-3D and IMERG rainfall at each time step over the North Eastern Region of India, which will dictate the suitability of the two rainfall product to be used for AI based rainfall prediction.</p>

Polar ice structure and the integrity of ice-core paleoclimate records

2010 ◽  
Vol 29 (1-2) ◽  
pp. 338-351 ◽  
Author(s):  
Sérgio H. Faria ◽  
Johannes Freitag ◽  
Sepp Kipfstuhl
Keyword(s):  
Ice Core ◽  
Polar Ice ◽  
Paleoclimate Records

scholarly journals South Pole glacial climate reconstruction from multi-borehole laser particulate stratigraphy

2013 ◽  
Vol 59 (218) ◽  
pp. 1117-1128 ◽  
Author(s):  
Keyword(s):  
Particle Physics ◽  
Volcanic Ash ◽  
Ice Core ◽  
Hot Water ◽  
Radiometric Dating ◽  
South Pole ◽  
Last Glacial Period ◽  
Annual Layer ◽  
Paleoclimate Records ◽  
The Last Glacial

AbstractThe IceCube Neutrino Observatory and its prototype, AMANDA, were built in South Pole ice, using powerful hot-water drills to cleanly bore >100 holes to depths up to 2500 m. The construction of these particle physics detectors provided a unique opportunity to examine the deep ice sheet using a variety of novel techniques. We made high-resolution particulate profiles with a laser dust logger in eight of the boreholes during detector commissioning between 2004 and 2010. The South Pole laser logs are among the most clearly resolved measurements of Antarctic dust strata during the last glacial period and can be used to reconstruct paleoclimate records in exceptional detail. Here we use manual and algorithmic matching to synthesize our South Pole measurements with ice-core and logging data from Dome C, East Antarctica. We derive impurity concentration, precision chronology, annual-layer thickness, local spatial variability, and identify several widespread volcanic ash depositions useful for dating. We also examine the interval around ∼74 ka recently isolated with radiometric dating to bracket the Toba (Sumatra) supereruption.

scholarly journals Synchronizing the Greenland ice core and radiocarbon timescales over the Holocene – Bayesian wiggle-matching of cosmogenic radionuclide records

2016 ◽  
Vol 12 (1) ◽  
pp. 15-30 ◽  
Author(s):  
F. Adolphi ◽  
R. Muscheler
Keyword(s):  
Statistical Approach ◽  
Ice Core ◽  
Ice Cores ◽  
The Holocene ◽  
Counting Error ◽  
Climate Reconstructions ◽  
Uncertainty Measurement ◽  
Uncertainty Estimates ◽  
Paleoclimate Records ◽  
Cosmogenic Radionuclide

Abstract. Investigations of past climate dynamics rely on accurate and precise chronologies of the employed climate reconstructions. The radiocarbon dating calibration curve (IntCal13) and the Greenland ice core chronology (GICC05) represent two of the most widely used chronological frameworks in paleoclimatology of the past  ∼  50 000 years. However, comparisons of climate records anchored on these chronologies are hampered by the precision and accuracy of both timescales. Here we use common variations in the production rates of 14C and 10Be recorded in tree-rings and ice cores, respectively, to assess the differences between both timescales during the Holocene. Compared to earlier work, we employ a novel statistical approach which leads to strongly reduced and yet, more robust, uncertainty estimates. Furthermore, we demonstrate that the inferred timescale differences are robust independent of (i) the applied ice core 10Be records, (ii) assumptions of the mode of 10Be deposition, as well as (iii) carbon cycle effects on 14C, and (iv) in agreement with independent estimates of the timescale differences. Our results imply that the GICC05 counting error is likely underestimated during the most recent 2000 years leading to a dating bias that propagates throughout large parts of the Holocene. Nevertheless, our analysis indicates that the GICC05 counting error is generally a robust uncertainty measurement but care has to be taken when treating it as a nearly Gaussian error distribution. The proposed IntCal13-GICC05 transfer function facilitates the comparison of ice core and radiocarbon dated paleoclimate records at high chronological precision.

scholarly journals Concept and Testing of a Remotely Operated Vehicle-Mountable Inductive Electrothermal Polar Under-Ice Corer

2017 ◽  
Vol 51 (6) ◽  
pp. 33-43 ◽  
Author(s):  
Narayanaswamy Vedachalam ◽  
Arumugam Vadivelan ◽  
Arunachalam Umapathy ◽  
Munusamy Murugesan ◽  
Gopal Durai ◽  
...  
Keyword(s):  
Ice Core ◽  
Input Power ◽  
Design Development ◽  
Polar Ice ◽  
Remotely Operated Vehicle ◽  
Element Analysis ◽  
Ice Shelves ◽  
Core Samples ◽  
Inner Diameter ◽  
Aided Design

AbstractIce core samples from the polar ice shelves contain valuable paleo-climatic records and information for understanding the unique polar under-ice ecosystem. This paper describes the finite element analysis-aided design, development, and qualification of a 63-mm-inner diameter, 250-mm-long variable power underwater remotely operated vehicle-mountable inductive ice corer (IIC) for collecting ice core samples beneath the polar ice shelves. It is determined that, with the IIC operating with an input power of 1,000 W at 30 kHz, it is possible to have an ice penetration rate of 14 mm/min and obtain an ice core of 51 mm in diameter. The experimental results are found to comply with the numerical model with an accuracy of 95%.

scholarly journals A 40 Year Record in an Ice Core from the Dunde Ice Cap, China (Abstract)

1988 ◽  
Vol 10 ◽  
pp. 221 ◽  
Author(s):  
Wu Xiaoling ◽  
Lonnie G. Thompson
Keyword(s):  
Oxygen Isotope ◽  
Ice Core ◽  
Field Work ◽  
Tibet Plateau ◽  
Ice Thickness ◽  
Ice Cap ◽  
Pulse Radar ◽  
The North ◽  
Isotope Profile ◽  
Isotope Content

A cooperative glacio-climatological ice-core drilling and analysis program, administered by LIGC and BPRC, has been carried out since 1984. The major objective of this study is to extract from the Dunde ice cap records of the general environmental conditions, which include drought, volcanic activity, moisture sources, glacier net balance and possibly temperature over the last 3000 years. In 1984 a group of 18 Chinese scientists and an American scientist spent 6 weeks on the Dunde ice cap. The central objective of their research was to evaluate the potential of the ice cap to yield a lengthy ice-core climate record. Results of the 1984 field work and 1985 laboratory analysis are submitted here. The Dunde ice cap (38°96′N, 96°24.5′E) is located in the north-eastern section of the Tibet plateau, China. Its length is 10.9 km; the width varies from 2.5 to 7.5 km. The total area of the ice cap is 57 km2. A 16 m core was drilled at the first site, located on a flat part of the ice cap, 5150 m a.s.l. A 10.2 m ice core was drilled at the ice cap summit (5300 m). A series of shallow cores and 2 m pits were excavated at each of the two sites and in the lower section of the ice cap. A mono-pulse radar unit was used to determine ice thickness. The ice thickness ranged between 94 and 167 m, with an average thickness of 140 m. Using a thermistor cable, minimum temperatures of −9.1° and −9.5 °C were measured in the 16 m hole and 10.2 m hole respectively. Microparticle analysis of the ice core from the Dunde ice cap revealed a very high dust content, on average 16 × 105 particles (≥0.63 to ≤16 μ in diameter) per ml of sample, i.e. 3−4 times higher than the microparticle content in the Quelccaya ice cap, Peru, and 100 times higher than in the core from Byrd Station, Antarctica. Oxygen-isotope content ranged between −12 and −14 per mil. Initially it was anticipated that the oxygen-isotope content would produce a more negative value in the Dunde ice cap. More work is required to explain the mechanism controlling δ18o variation in the ice core from the Dunde ice cap. The microparticles, oxygen-isotope content, conductivity, and tritium measurements, together with stratigraphy, temperature and density, are presented in the figures. The 40 year net-balance record reconstructed from the ice-core and oxygen-isotope profile is in good agreement with data from precipitation and major temperature trends obtained for the last 30 years from Delingha meteorological station, which is located 160 km south-east of the ice cap.

scholarly journals Polar ice stratigraphy from laser-light scattering: scattering from meltwater

1994 ◽  
Vol 40 (136) ◽  
pp. 504-508 ◽  
Author(s):  
Michael Ram ◽  
Matthias Illing
Keyword(s):  
Light Scattering ◽  
Sample Size ◽  
Tree Ring ◽  
Laser Light ◽  
Ice Core ◽  
Ice Cores ◽  
Laser Light Scattering ◽  
Polar Ice ◽  
The Core ◽  
Considerable Success

Abstract We describe a new laser-light-scattering instrument for measuring variations in dust concentration along polar ice cores. We have used this instrument with considerable success on the GISP2 ice core from central Greenland. Reproducibility is excellent and the required ice-sample size is relatively small. When combined with visual stratigraphy and ECM, the distinct annual spring/ summer dust peaks we observe can be used to date the core with tree-ring-like precision.

scholarly journals Towards radiocarbon dating of ice cores

2009 ◽  
Vol 55 (194) ◽  
pp. 985-996 ◽  
Author(s):  
M. Sigl ◽  
T.M. Jenk ◽  
T. Kellerhals ◽  
S. Szidat ◽  
H.W. Gäggeler ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Core ◽  
Ice Cores ◽  
Swiss Alps ◽  
Carbonaceous Aerosol ◽  
Polar Ice ◽  
Low Latitude ◽  
Bolivian Andes ◽  
Glacier Ice ◽  
Dating Method

AbstractA recently developed dating method for glacier ice, based on the analysis of radiocarbon in carbonaceous aerosol particles, is thoroughly investigated. We discuss the potential of this method to achieve a reliable dating using examples from a mid- and a low-latitude ice core. Two series of samples from Colle Gnifetti (4450 m a.s.l., Swiss Alps) and Nevado Illimani (6300 m a.s.l., Bolivian Andes) demonstrate that the 14C ages deduced from the water-insoluble organic carbon fraction represent the age of the ice. Sample sizes ranged between 7 and 100 μg carbon. For validation we compare our results with those from independent dating. This new method is thought to have major implications for dating non-polar ice cores in the future, as it provides complementary age information for time periods not accessible with common dating techniques.

Environmental records from polar ice cores

1990 ◽  
Vol 330 (1615) ◽  
pp. 459-462 ◽  
Keyword(s):  
Solar Activity ◽  
Ice Core ◽  
Ice Cores ◽  
Polar Ice ◽  
Cosmogenic Isotope ◽  
Wide Range ◽  
Recent Part ◽  
Ice Core Records

Polar ice cores provide a wide range of information on past atmospheric climate (temperature, precipitation) and environment (gas and aerosol concentrations). The dating can be very accurate for the more recent part of the records but accuracy decreases with depth and time. Measurements of cosmogenic isotope concentrations (such as 10 Be) provide information on palaeo-precipitation rates and particular events can be used to correlate ice core records. Besides these climatic applications, 10 Be concentration records in ice cores also contain information on solar activity changes.

scholarly journals Measurements of CO2 and CH4 concentrations in air in a polar ice core

1993 ◽  
Vol 39 (132) ◽  
pp. 209-215 ◽  
Author(s):  
Takakiyo Nakazawa ◽  
Toshinobu Machida ◽  
Kenji Esumi ◽  
Masayuki Tanaka ◽  
Yoshiyuki Fujii ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Preliminary Analysis ◽  
Extraction Efficiency ◽  
Ice Core ◽  
Fine Powder ◽  
Glacial Period ◽  
Polar Ice ◽  
The Core ◽  
Precise Analysis ◽  
Better Than

AbstractDry and wet air-extraction systems and precise analysis systems of the CO2and CH4concentrations for a polar ice core were developed to reconstruct their ancient levels. A dry-extraction system was capable of crushing an ice sample of 1000 g into fine powder within 2 min, and its air-extraction efficiency was found to be 98%. The CO2and CH4concentrations of extracted air were determined using gas chromatography with a flame-ionized detector. The overall precision of our measurements, including air extraction, was estimated to be better than ± 1 ppmv for CO2and + 10 ppbv for CH4. Preliminary analysis of the ice core drilled at Mizuho Station, Antarctica, showed that the CO2and CH4concentrations at 3340–3700 year BP were about 280 ppmv and 700ppbv, respectively. The Yamato core drilled at the terminus of the glacial flow near the Yamato Mountains, Antarctica, yielded concentrations of 230–240 ppmv for CO2and 520–550 ppbv for CH4, suggesting that the core had formed during the glacial period.

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