scholarly journals Weaker axially dipolar time-averaged paleomagnetic field based on multidomain-corrected paleointensities from Galapagos lavas

2015 ◽  
Vol 112 (49) ◽  
pp. 15036-15041 ◽  
Author(s):  
Huapei Wang ◽  
Dennis V. Kent ◽  
Pierre Rochette
Keyword(s):  
Field Strength ◽  
Mean Field ◽  
Axial Dipole ◽  
The Past ◽  
Galapagos Archipelago ◽  
The Earth ◽  
Geocentric Axial Dipole ◽  
Dynamo Process ◽  
Comprehensive Study

The geomagnetic field is predominantly dipolar today, and high-fidelity paleomagnetic mean directions from all over the globe strongly support the geocentric axial dipole (GAD) hypothesis for the past few million years. However, the bulk of paleointensity data fails to coincide with the axial dipole prediction of a factor-of-2 equator-to-pole increase in mean field strength, leaving the core dynamo process an enigma. Here, we obtain a multidomain-corrected Pliocene–Pleistocene average paleointensity of 21.6 ± 11.0 µT recorded by 27 lava flows from the Galapagos Archipelago near the Equator. Our new result in conjunction with a published comprehensive study of single-domain–behaved paleointensities from Antarctica (33.4 ± 13.9 µT) that also correspond to GAD directions suggests that the overall average paleomagnetic field over the past few million years has indeed been dominantly dipolar in intensity yet only ∼60% of the present-day field strength, with a long-term average virtual axial dipole magnetic moment of the Earth of only 4.9 ± 2.4 × 1022 A⋅m2.

Plant leaf recognition with shallow and deep learning: A comprehensive study

2020 ◽  
Vol 24 (6) ◽  
pp. 1311-1328
Author(s):  
Jozsef Suto
Keyword(s):  
Machine Learning ◽  
Plant Species ◽  
Research Area ◽  
Research Papers ◽  
Plant Leaf ◽  
Leaf Characteristics ◽  
The Past ◽  
The Earth ◽  
Test Sets ◽  
Comprehensive Study

Nowadays there are hundreds of thousands known plant species on the Earth and many are still unknown yet. The process of plant classification can be performed using different ways but the most popular approach is based on plant leaf characteristics. Most types of plants have unique leaf characteristics such as shape, color, and texture. Since machine learning and vision considerably developed in the past decade, automatic plant species (or leaf) recognition has become possible. Recently, the automated leaf classification is a standalone research area inside machine learning and several shallow and deep methods were proposed to recognize leaf types. From 2007 to present days several research papers have been published in this topic. In older studies the classifier was a shallow method while in current works many researchers applied deep networks for classification. During the overview of plant leaf classification literature, we found an interesting deficiency (lack of hyper-parameter search) and a key difference between studies (different test sets). This work gives an overall review about the efficiency of shallow and deep methods under different test conditions. It can be a basis to further research.

scholarly journals Statistics and Analysis of the Relations between Rainstorm Floods and Earthquakes

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Baodeng Hou ◽  
Yongxiang Wu ◽  
Jianhua Wang ◽  
Kai Wu ◽  
Weihua Xiao
Keyword(s):  
Climate Change ◽  
Input Data ◽  
Computational Results ◽  
Occurrence Time ◽  
The Past ◽  
The Earth ◽  
Water Vapors ◽  
Transmission Zone ◽  
Chinese Scholars

The frequent occurrence of geophysical disasters under climate change has drawn Chinese scholars to pay their attention to disaster relations. If the occurrence sequence of disasters could be identified, long-term disaster forecast could be realized. Based on the Earth Degassing Effect (EDE) which is valid, this paper took the magnitude, epicenter, and occurrence time of the earthquake, as well as the epicenter and occurrence time of the rainstorm floods as basic factors to establish an integrated model to study the correlation between rainstorm floods and earthquakes. 2461 severe earthquakes occurred in China or within 3000 km from China and the 169 heavy rainstorm floods occurred in China over the past 200+ years as the input data of the model. The computational results showed that although most of the rainstorm floods have nothing to do with the severe earthquakes from a statistical perspective, some floods might relate to earthquakes. This is especially true when the earthquakes happen in the vapor transmission zone where rainstorms lead to abundant water vapors. In this regard, earthquakes are more likely to cause big rainstorm floods. However, many cases of rainstorm floods could be found after severe earthquakes with a large extent of uncertainty.

Long-term changes in the rotation of the Earth : 700 B.C. to A.D. 1980

1984 ◽  
Vol 313 (1524) ◽  
pp. 47-70 ◽  
Keyword(s):  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Temporal Behaviour ◽  
Tidal Friction ◽  
The Past ◽  
The Earth ◽  
Tidal Changes ◽  
Rotation Of The Earth ◽  
Tidal Variations

Occultations of stars by the Moon, and solar and lunar eclipses are analysed for variations in the Earth’s rotation over the past 2700 years. Although tidal braking provides the dominant, long-term torque, it is found that the rate of rotation does not decrease uniformly as would be expected if tidal friction were the only mechanism affecting the Earth’s rotation. There are also non-tidal changes present that vary on timescales ranging from decades to millennia. The magnitudinal and temporal behaviour of these non-tidal variations are evaluated in this paper.

Gaia or Athena? The Early Faint-Sun Paradox

1997 ◽  
Author(s):  
Douglas V. Hoyt ◽  
Kenneth H. Shatten
Keyword(s):  
Carbon Dioxide ◽  
Solar Radiation ◽  
Surface Temperature ◽  
Stellar Evolution ◽  
The Sun ◽  
Solar Luminosity ◽  
The Past ◽  
The Earth ◽  
Climate Evolution

Stellar evolution theory predicts large, long-term solar large, long-term solar luminosity (L⊙) changes over the lifetime of the sun. The most certain prediction is a general monotonic increase (neglecting short-period variations) in L⊙ of about 30% over the past 4.7 billion years, an increase that will continue. This prediction is well founded theoretically (based on the conversion of hydrogen into heavier elements) and supported observationally by the famous Hertzsprung-Russell diagram showing stellar evolution. If the solar luminosity increases monotonically with time, one might expect to find evidence of increasing surface temperatures in the Earth’s paleoclimatic record. Instead, isotopic indicators show Earth’s mean surface temperature is now significantly lower than it was 3 billion years ago. In 1975, R. K. Ulrich termed this the “faint young sun” paradox. Simultaneous solar luminosity increase and terrestrial temperature decrease imply additional strong influences on climate evolution. To understand climate evolution (and, by inference, the present climate), we must first determine the nature of these “compensatory mechanisms.” The positively increasing line in Figure 12.1 shows the evolution of solar luminosity (in units of present luminosity, L). Since terrestrial surface temperatures have remained nearly constant during the last 2.3 billion years, this requires a very effective compensatory mechanism. Several theories attempt to explain why the Earth’s surface temperature has remained relatively constant even while the solar luminosity has increased by 30%. Also, various scenarios have been advanced to explain why the Earth remained ice-free even during periods when the sun was much dimmer than it is today. Some of these ideas are: • Since it had fewer continents and more oceans, the early Earth was much darker. This same darker surface absorbed enough additional incoming solar radiation to remain ice-free. • In the past, energy transport from the equator to polar regions was easier because the continents had lower elevations. This enhanced heat transport allowed the Earth to remain relatively warm. • The early atmosphere had more carbon dioxide and methane, creating an enhanced greenhouse effect sufficient to trap the incoming solar radiation and keep the Earth warm. The enormous amount of carbon trapped in limestone suggests that Earth’s former atmosphere contained much more carbon dioxide than it does today.

Field Intensity changes during the past 40 ka

2020 ◽  
Author(s):  
Jean-Pierre Valet ◽  
Franck Bassinot ◽  
Ramon Egli ◽  
Anojh Thevarasan
Keyword(s):  
Dipole Moments ◽  
Field Vector ◽  
Historical Period ◽  
Directional Information ◽  
Sedimentary Records ◽  
Axial Dipole ◽  
The Past ◽  
Intensity Changes ◽  
Volcanic Lava

<p>The period encompassing the past 40 ka is crucial to constrain the characteristic time of the axial dipole, which is computed so far from the historical period and still fails to be tested against long-term field changes. The past 7 kyr of geomagnetic history are primarily documented from archeological artefacts, yet the last 4 kyr remain relatively poorly constrained. Beyond this period, we are dealing with long-term changes of the dipole field that are relatively poorly documented by sedimentary records or by volcanic lava flows. Many measurements of absolute paleointensity do not incorporate directional information, while it is crucial to document the entire field vector and consequently can only be analyzed in terms of virtual axial dipole moments (VADM). In summary, no high resolution dataset covers the field changes which followed the Laschamp event and therefore we have poor knowledge of the pattern of fluctuations and the rate of the changes that were associated with the field recovery after the Laschamp. We have selected a set of marine sedimentary cores based on the quality of their oxygen isotope records. Their deposition rates are comprised between 10 and 20 cm/ka and therefore offer a great potential to constrain the filed intensity changes with a resolution of the order of 100 ka. during this period. We will present the results obtained from 7 marine core records and investigate their common and their discrepant features in order to identify the true paleointensity signal.</p><p> </p>

IX. Discussion

1965 ◽  
Vol 258 (1088) ◽  
pp. 107-108
Keyword(s):  
Geophysical Methods ◽  
Continental Drift ◽  
Tectonic Activity ◽  
Geological Time ◽  
The Past ◽  
Current State ◽  
The Earth ◽  
Long Term Changes ◽  
History Of

Although the primary subject of the Symposium was continental drift, this is only one aspect of a larger problem. Eventually, consideration of changes in magmatic, metamorphic and tectonic activity through the history of the crust should enable us to put forward a hypothesis to account for the behaviour of the upper parts of the Earth through geological time. As had been pointed out, most geophysical methods provided information about the current state of the Earth and part of the great value of palaeomagnetic studies lay in the fact that they produced information about the past. Some information about the behaviour of possible convection cells during continental drift could be obtained from other long-term changes in the crust. The incidence of magmatic and metamorphic activity gave some indication as to the distribution of regions where there had been an unusually high accession of heat in the past.

scholarly journals Heat stored in the Earth system: Where does the energy go? The GCOS Earth heat inventory team

2020 ◽  
Author(s):  
Karina von Schuckmann ◽  
Lijing Cheng ◽  
Matthew D. Palmer ◽  
Caterina Tassone ◽  
Valentin Aich ◽  
...  
Keyword(s):  
Global Climate ◽  
Atmospheric Composition ◽  
Global Ocean ◽  
Earth System ◽  
Heat Gain ◽  
The Past ◽  
The Earth ◽  
International Assessment ◽  
Composition Changes

Abstract. Human-induced atmospheric composition changes cause a radiative imbalance at the top-of-atmosphere which is driving global warming. This Earth Energy Imbalance (EEI) is a fundamental metric of climate change. Understanding the heat gain of the Earth system from this accumulated heat – and particularly how much and where the heat is distributed in the Earth system – is fundamental to understanding how this affects warming oceans, atmosphere and land, rising temperatures and sea level, and loss of grounded and floating ice, which are fundamental concerns for society. This study is a Global Climate Observing System (GCOS) concerted international effort to update the Earth heat inventory, and presents an updated international assessment of ocean warming estimates, and new and updated estimates of heat gain in the atmosphere, cryosphere and land over the period 1960–2018. The study obtains a consistent long-term Earth system heat gain over the past 58 years, with a total heat gain of 393 ± 40 ZJ, which is equivalent to a heating rate of 0.42 ± 0.04 W m−2. The majority of the heat gain (89 %) takes place in the global ocean (0–700 m: 53 %; 700–2000 m: 28 %; > 2000 m: 8 %), while it amounts to 6 % for the land heat gain, to 4 % available for the melting of grounded and floating ice, and to 1 % for atmospheric warming. These new estimates indicate a larger contribution of land and ice heat gain (10 % in total) compared to previous estimates (7 %). There is a regime shift of the Earth heat inventory over the past 2 decades, which appears to be predominantly driven by heat sequestration into the deeper layers of the global ocean, and a doubling of heat gain in the atmosphere. However, a major challenge is to reduce uncertainties in the Earth heat inventory, which can be best achieved through the maintenance of the current global climate observing system, its extension into areas of gaps in the sampling, as well as to establish an international framework for concerted multi-disciplinary research of the Earth heat inventory. Earth heat inventory is published at DKRZ (https://www.dkrz.de/) under the doi: https://doi.org/10.26050/WDCC/GCOS_EHI_EXP (von Schuckmann et al., 2020).

China’s Environmental Governance and Law Development Review Based on Co-Word Analysis

2013 ◽  
Vol 295-298 ◽  
pp. 2172-2176 ◽  
Author(s):  
Zhong Mei Liu ◽  
Xu Kun Wang
Keyword(s):  
Environmental Governance ◽  
Technology Development ◽  
Environmental Law ◽  
Research Focus ◽  
Word Analysis ◽  
The Past ◽  
Theory To Practice ◽  
The Subject ◽  
Comprehensive Study

The research and development situation of environmental governance in the past thirty years may be intuitively acquired with the co-word analysis in the interdisciplinary environmental law. This paper analyzes the research focus and transformation situation of China’s environment governance and law by searching related papers with the subject words “environmental law” in Chinese Journal Full-text Database. The co-word analysis results show environmental law research showed five main knowledge focuses, such as international environmental law, sustainable development, environmental right, participation, and environment conservation. And according to the co-word analysis, environmental law research may be divided into four stages: foundation, prosperity, from theory to practice transformation, and challenge stage of environmental law response to new environment problems. By analysis of the research focus, we can know China’s researchers in the environmental governance policy or law should strengthen the scientific, pertinence and prospective characteristics of environmental law research, make interdisciplinary and comprehensive study combined with China long-term science and technology development.

The Origin of the Moon and its Relationship to the Origin of the Solar System

1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey
Keyword(s):  
Solar System ◽  
The Moon ◽  
The Past ◽  
The Earth ◽  
Short Period ◽  
Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

Enabling Community Well-being Self-Monitoring in the Context of Mining: The Naskapi Nation of Kawawachikamach

2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Robert Klinck ◽  
Ben Bradshaw ◽  
Ruby Sandy ◽  
Silas Nabinacaboo ◽  
Mannie Mameanskum ◽  
...  
Keyword(s):  
Indigenous Peoples ◽  
Well Being ◽  
Aboriginal Community ◽  
Self Monitoring ◽  
Community Engaged Research ◽  
The Past ◽  
Mineral Development ◽  
Iron Deposits ◽  
Term Monitoring

The Naskapi Nation of Kawawachikamach is an Aboriginal community located in northern Quebec near the Labrador Border. Given the region’s rich iron deposits, the Naskapi Nation has considerable experience with major mineral development, first in the 1950s to the 1980s, and again in the past decade as companies implement plans for further extraction. This has raised concerns regarding a range of environmental and socio-economic impacts that may be caused by renewed development. These concerns have led to an interest among the Naskapi to develop a means to track community well-being over time using indicators of their own design. Exemplifying community-engaged research, this paper describes the beginning development of such a tool in fall 2012—the creation of a baseline of community well-being against which mining-induced change can be identified. Its development owes much to the remarkable and sustained contribution of many key members of the Naskapi Nation. If on-going surveying is completed based on the chosen indicators, the Nation will be better positioned to recognize shifts in its well-being and to communicate these shifts to its partners. In addition, long-term monitoring will allow the Naskapi Nation to contribute to more universal understanding of the impacts of mining for Indigenous peoples.

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