Correction for Geomagnetic Secular Variation Effects: A New Method (Case Study of the Altai Geodynamic Network)

2021 ◽  
Vol 62 (2) ◽  
pp. 255-262
Author(s):  
D.A. Kuleshov ◽  
P.G. Dyadkov ◽  
V.V. Plotkin
Keyword(s):  
Secular Variation ◽  
Surface Deformation ◽  
Liquid Core ◽  
New Method ◽  
Space Distribution ◽  
Main Magnetic Field ◽  
Positive Anomaly ◽  
Geomagnetic Secular Variation ◽  
Using Data ◽  
Curie Surface

Abstract ––The study focuses on detection of geomagnetic secular variation and the respective correction of tectonomagnetic data. A new technique is proposed for picking the secular variation component in the Earth’s main magnetic field recorded by precise measurements at 100 to 500 km sites on the surface. Long-period field variations presumably arise from fluid motions in the liquid core, at depths of 3000 km, whereas the sizes of observation networks are within 500 km. The sources of secular variation, irrespective of their configuration, are much deeper than those of tectonomagnetic anomalies located above the Curie surface depths of ~10 to 20 km. Therefore, the surfaces that represent the space distribution of secular variation must be smoother than the respective surfaces for tectonomagnetic anomalies. The problem is thus to separate the regional and local signals from the two types of sources located at different depths. The new method is tested using data of yearly geomagnetic measurements at more than 30 repeat stations of a ~120 km long geodynamic network in Gorny Altai spanning the period from 2004 through 2018. The secular variation pattern is reconstructed by quadratic interpolation. The precise data corrected for secular variation of the main field reveal previously hidden tectonomagnetic anomalies up to 12 nT. The 3 nT positive anomaly falls within the zone of surface deformation caused by the Mw = 7.3 Chuya earthquake of 27 September 2003.

scholarly journals Predictions of the geomagnetic secular variation based on the ensemble sequential assimilation of geomagnetic field models by dynamo simulations

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Sabrina Sanchez ◽  
Johannes Wicht ◽  
Julien Bärenzung
Keyword(s):  
Magnetic Field ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Wave Number ◽  
Main Magnetic Field ◽  
Candidate Model ◽  
Uncertainty Estimates ◽  
Geomagnetic Field Models ◽  
Dipole Configuration

Abstract 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.

scholarly journals A Model for Selecting a Strategic Information System Using the FITradeoff

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Ana Paula Henriques de Gusmão ◽  
Cristina Pereira Medeiros
Keyword(s):  
Information System ◽  
Information Systems ◽  
Decision Maker ◽  
Additive Model ◽  
New Method ◽  
Strategic Information ◽  
Perceived Need ◽  
Using Data ◽  
Strategic Information System ◽  
Glass Packaging

This paper arose from the perceived need to make a contribution towards assessing a strategic information system by using a new method for eliciting the weights of criteria. This is considered one of the most complex and important stages in multicriteria models. Multicriteria models have been proposed to support decisions in the context of information systems given that problems in this field deal with many conflicting criteria. The new procedure for eliciting the weights of the criteria has the advantage of requiring less effort from the decision-maker and, thus, the risk of inconsistent answers is minimized. Therefore, a model based on this new procedure is proposed and applied using data from a glass packaging factory that needs to select a single information system from a set of systems previously identified as relevant. The results obtained are consistent both with the performance of alternatives and with the additive model used to evaluate the alternatives.

Functional Analysis of Intermittently Reinforced Behaviour: A Case Study

1999 ◽  
Vol 16 (4) ◽  
pp. 219-225 ◽  
Author(s):  
Don Tustin
Keyword(s):  
Functional Analysis ◽  
Problem Solving ◽  
Personality Disorder ◽  
Revealed Preference ◽  
New Method ◽  
Dependent Personality Disorder ◽  
Dependent Personality ◽  
Standard Problem ◽  
Using Data

AbstractFunctional analysis is used to identify potential reinforcers by generating hypotheses about possible functions of a behaviour. Current methods of functional analysis emphasise observations of events, especially consequences, that occur in the immediate environment of the behaviour. While these methods are well suited for assessing behaviour that is reinforced frequently, they are less appropriate for assessing behaviour that is reinforced only intermittently. A new method for conducting functional analysis is presented that is designed to assess intermittently reinforced behaviour. The new method is illustrated using data that were gathered from an extension of a standard problem-solving format. Data are interpreted using the principle of revealed preference that arose from behavioural economics. The revealed preference method is illustrated using information provided by a client with a dependent personality disorder.

scholarly journals A simple new method for identifying performance characteristics associated with success in elite tennis

2018 ◽  
Vol 14 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Anna Fitzpatrick ◽  
Joseph A Stone ◽  
Simon Choppin ◽  
John Kelley
Keyword(s):  
Performance Analysis ◽  
Statistical Methods ◽  
Rank Order ◽  
Large Datasets ◽  
Performance Characteristics ◽  
New Method ◽  
Considerable Time ◽  
Simple Method ◽  
Suitable Alternative ◽  
Using Data

Performance analysis and identifying performance characteristics associated with success are of great importance to players and coaches in any sport. However, while large amounts of data are available within elite tennis, very few players employ an analyst or attempt to exploit the data to enhance their performance; this is partly attributable to the considerable time and complex techniques required to interpret these large datasets. Using data from the 2016 and 2017 French Open tournaments, we tested the agreement between the results of a simple new method for identifying important performance characteristics (the Percentage of matches in which the Winner Outscored the Loser, PWOL) and the results of two standard statistical methods to establish the validity of the simple method. Spearman’s rank-order correlations between the results of the three methods demonstrated excellent agreement, with all methods identifying the same three performance characteristics ( points won of 0–4 rally length, baseline points won and first serve points won) as strongly associated with success. Consequently, we propose that the PWOL method is valid for identifying performance characteristics associated with success in tennis, and is therefore a suitable alternative to more complex statistical methods, as it is simpler to calculate, interpret and contextualise.

scholarly journals Four decades of European geomagnetic secular variation and acceleration

2010 ◽  
Vol 52 (5) ◽  
Author(s):  
Giuliana Verbanac ◽  
Monika Korte ◽  
Mioara Mioara Mandea
Keyword(s):  
Secular Variation ◽  
Geomagnetic Secular Variation

scholarly journals Fluid pressure arrival-time tomography: Estimation and assessment in the presence of inequality constraints with an application to production at the Krechba field, Algeria

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. O39-O55 ◽  
Author(s):  
Alessio Rucci ◽  
D. W. Vasco ◽  
Fabrizio Novali
Keyword(s):  
Surface Deformation ◽  
Transient Flow ◽  
Fluid Pressure ◽  
Inequality Constraints ◽  
Gas Production ◽  
Gas Field ◽  
Peak Displacement ◽  
Geomechanical Properties ◽  
Fluid Production ◽  
Using Data

Deformation in the overburden proves useful in deducing spatial and temporal changes in the volume of a producing reservoir. Based on these changes, we have estimated diffusive traveltimes associated with the transient flow due to production, and then, as the solution of a linear inverse problem, the effective permeability of the reservoir. An advantage of the approach based on traveltimes, as opposed to one based on the amplitude of surface deformation, is that it is much less sensitive to the exact geomechanical properties of the reservoir and overburden. Inequalities constrain the inversion, under the assumption that the fluid production only results in pore volume decreases within the reservoir. The formulation has been applied to satellite-based estimates of deformation in the material overlying a thin gas production zone at the Krechba field in Algeria. The peak displacement after three years of gas production is found to be approximately [Formula: see text], overlying the eastern margin of the anticlinal structure defining the gas field. Using data from 15 irregularly spaced images of range change, we have calculated the diffusive traveltimes associated with the startup of a gas production well. The inequality constraints were incorporated into the estimates of model parameter resolution and covariance, improving the resolution by roughly 30% to 40%.

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