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Predicting the Magnetic Poles' Shift Using Machine Learning
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The IGRF offers an important incentive for testing algorithms predicting the Earth’s magnetic field changes, known as secular variation (SV), in a 5-year range. Here, we present a SV candidate model for the 13th IGRF that stems from a sequential ensemble data assimilation approach (EnKF). The ensemble consists of a number of parallel-running 3D-dynamo simulations. The assimilated data are geomagnetic field snapshots covering the years 1840 to 2000 from the COV-OBS.x1 model and for 2001 to 2020 from the Kalmag model. A spectral covariance localization method, considering the couplings between spherical harmonics of the same equatorial symmetry and same azimuthal wave number, allows decreasing the ensemble size to about a 100 while maintaining the stability of the assimilation. The quality of 5-year predictions is tested for the past two decades. These tests show that the assimilation scheme is able to reconstruct the overall SV evolution. They also suggest that a better 5-year forecast is obtained keeping the SV constant compared to the dynamically evolving SV. However, the quality of the dynamical forecast steadily improves over the full assimilation window (180 years). We therefore propose the instantaneous SV estimate for 2020 from our assimilation as a candidate model for the IGRF-13. The ensemble approach provides uncertainty estimates, which closely match the residual differences with respect to the IGRF-13. Longer term predictions for the evolution of the main magnetic field features over a 50-year range are also presented. We observe the further decrease of the axial dipole at a mean rate of 8 nT/year as well as a deepening and broadening of the South Atlantic Anomaly. The magnetic dip poles are seen to approach an eccentric dipole configuration.
Principally new model of the magnetic field of the Hot Earth is proposed. Unlike the commonly accepted approach which considers that the Earth’s temperature doesn’t increase because heat released under selfgravitation is removed through radiation our model assumes that early substance of the Earth heated up to 30 000 K was a superheated and overcompressed vapour.
Cooling the Earth substance was condensing. The system was expanding adiabatically that governed the character of the Earth enlargement. This scheme origins from the phase transition (PT) of condensation-evaporation under the benefit of condensation. PT provides the heat, geodynamics of expansion and the Earth’s magnetic field (EMF).
The high temperature of the substance causes its thermoionization, whereas PT operation relating to mass transfer initiates charges separation and generation of the double electric layer (DEL). A diurnal rotation of DEL induces a weak initial EMF which enhances then at the expense of the Hall dynamo (Hall current) inside PT area. The benefit of evaporation causes the Earth compression and reversal of the EMF polarity.
The approach we develop provides an insight into features of the magnetic field of the planets and satellites at the Sun system.
The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the
Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates
the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0,
and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the
IGRF model, provide the spherical harmonic coefficients, and provide maps of the magnetic declination, inclination,
and total intensity for epoch 2015.0 and their predicted rates of change for 2015.0-2020.0. We also update the
magnetic pole positions and discuss briefly the latest changes and possible future trends of the Earth’s magnetic field.
The north magnetic dip pole velocity has more than doubled in the last 30 years. This observation, together with the decrease in the Earth's magnetic dipole intensity over the last century has raised the concern of a possible approaching polarity reversal. We show that this rapid variation is in fact to be expected, and will not affect the dipolar field as a whole, but only the north magnetic pole. We demonstrate how this rapid displacement of the north magnetic pole is made possible by the horizontal field morphology. This rapid variation of north magnetic pole position does not imply any important modification of the core processes associated with field generation. The north magnetic pole position being very sensitive to small as well as rapid variations of the field, we show that it can very effectively be used as a passive tracer (or indicator) of field variations. Indeed, its velocity over the last century very accurately indicates the geomagnetic impulses (or jerks) that were so far observed only in observatory data.
The retrieval of similar type of data is performed by requesting the query, generally through personal computer. As the smart mobile devices are available at the general user, retrieval of visually similar data is now performed on these devices such as smart phones, PDA etc. A wireless medium is the key component of mobile devices and visually similar image retrieval with minimum latency is the typical issue.Hence the main objective of our proposed work is to develop the efficient mechanism for image retrieval on mobile devices. The image representation scheme V-HOG captures the useful information from the image with the help of gradient vector and the gradients are calculated by using various block size. The size of block, cell and bins are the main components which are varied and developed the V-HOG with feature values 1296, 1176, 672. The experimentation are conceded on the standard Holidays Dataset. The proposed V-HOG approach having a feature value 1296, 1176 and 672 perform better with existing HOG. In comparison with HOG, the precision and recall rate for V-HOG is improved by 27% to 90% and 7% to 32% respectively. The retrieval time is also reduced to 3% to 9%. The proposed V-HOG with 1176 feature perform well and having a good precision and recall rate.
The purpose of this review is to outline the definition and method of derivation of the indices of geomagnetic activity that are most commonly used at present. The first part of the review presents the methods of derivation of Kp, ap, AE, and Dst; the second part involves a discussion of the strengths and weaknesses of each index. It is shown that the distribution of magnetic observatories whose data are used in the production of the indices strongly influences the quantitative reliability of the indices in varying degrees. Furthermore, it is found that, in general, indices are only capable of defining the lower limit of geomagnetic activity at any given time. It is concluded that indices should only be used in statistical studies of solar-terrestrial interactions; their use in the study of individual events is generally not advisable.
Locations of the geomagnetic pole over the past 10,000 years have been calculated by averaging the VGP positions obtained from paleomagnetic data. The distribution of the geomagnetic pole was elongated to the direction parallel to the meridian of 45° and 225° longitude, and westward movement of the pole was predominant throughout this period. The time sequence of the polar motion can be divided into three intervals, the intervals between ca. 10,000 B.P. and ca. 7000 B.P., between ca. 7000 B.P. and ca. 3700 B.P., and between ca. 3700 B.P. and the present. During the period between ca. 7000 and ca. 3700 B.P., the range of the movement of the geomagnetic pole was limited within 5 degrees around the geographical pole. Before and after this period, the movement was very active, fluctuating over 10 degrees. The results of the last 2000 years show good consistency with the geomagnetic pole calculated from archaeomagnetic data by Merrill and McElhinny [1983].
Using a unified approach, expressions are derived for the various pole
positions and other dipole parameters for the centered and eccentric
dipole models of the earth's magnetic field. The pole positions and
other parameters are then calculated using the 1945 - 1985 International
Geomagnetic Reference Field Gauss coefficients and coefficients from
models of the earth's field for earlier epochs. Comparison is made
between (1) the recent pole positions and those pertaining since 1600
and (2) the various theoretical pole positions and the observed dip pole
positions.