High-resolution secular variation of the geomagnetic field in western Europe over the last 4 centuries: Comparison and integration of historical data from Paris and London

1997 ◽  
Vol 102 (B9) ◽  
pp. 20245-20258 ◽  
Author(s):  
Mioara Alexandrescu ◽  
Vincent Courtillot ◽  
Jean-Louis Le Mouël
Keyword(s):  
High Resolution ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Western Europe ◽  
Historical Data

High-resolution paleomagnetic secular variation and relative paleointensity records from the western Canadian Arctic: implication for Holocene stratigraphy and geomagnetic field behaviourThis article is one of a series of papers published in this Special Issue on the theme Polar Climate Stability Network.GEOTOP Contribution 2008-0024.

2008 ◽  
Vol 45 (11) ◽  
pp. 1265-1281 ◽  
Author(s):  
Francesco Barletta ◽  
Guillaume St-Onge ◽  
James E.T. Channell ◽  
André Rochon ◽  
Leonid Polyak ◽  
...  
Keyword(s):  
Dipole Moment ◽  
High Resolution ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Special Issue ◽  
Polar Climate ◽  
Climate Stability ◽  
Relative Paleointensity ◽  
Holocene Stratigraphy ◽  
Field Behaviour

Two piston cores recovered from the Chukchi and the Beaufort seas document Arctic Holocene geomagnetic field behaviour and highlight the potential of secular variation and relative paleointensity as a regional chronostratigraphic tool. Several centennial- to millennial-scale Holocene declination and inclination features can be correlated in both cores, with other high-resolution western North American lacustrine and volcanic paleomagnetic records and with records of changes in Earth’s dipole moment, supporting the geomagnetic origin of these features and implying that they are associated with changes in Earth’s dipole moment.

Historical observations of the geomagnetic field

1982 ◽  
Vol 306 (1492) ◽  
pp. 71-78 ◽  
Keyword(s):  
Sixteenth Century ◽  
Spherical Harmonics ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Historical Data ◽  
Intensity Information

Reliable observations of the geomagnetic field date back to the sixteenth century. Several compilations of old data have been made, of which one of the most extensive is the catalogue of Veinberg & Shibaev. At some localities, notably London and Paris, long series of observations exist at the same or neighbouring sites. Such series are useful for the information they give on the behaviour of the secular variation of the geomagnetic field. Sources of historical observations suffer from several basic defects. For instance, until about 1850, the available data were restricted almost entirely to observations of the direction of the field. Ways of overcoming this lack of intensity information are discussed. A convenient way of using global collections of historical data is to produce from them models of the geomagnetic field at past epochs. These models, which usually take the form of expansions in terms of spherical harmonics, can then be used in attempts to study the evolution of certain core processes.

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.

High-resolution melting PCR assay as a powerful tool for the epidemiological surveillance of tularemia in Western Europe

2021 ◽  
Vol 90 ◽  
pp. 104741
Author(s):  
Maëllys Kevin ◽  
Guillaume Girault ◽  
Yvan Caspar ◽  
Moulay Ali Cherfa ◽  
Christiane Mendy ◽  
...  
Keyword(s):  
High Resolution ◽  
Western Europe ◽  
High Resolution Melting ◽  
Epidemiological Surveillance ◽  
Pcr Assay

scholarly journals Geomagnetic Virtual Observatories: monitoring geomagnetic secular variation with the Swarm satellites

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Magnus D. Hammer ◽  
Grace A. Cox ◽  
William J. Brown ◽  
Ciarán D. Beggan ◽  
Christopher C. Finlay
Keyword(s):  
Time Series ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Time Windows ◽  
Low Earth Orbit ◽  
Data Selection ◽  
Spherical Harmonic Analysis ◽  
Core Field ◽  
The Core ◽  
Swarm Satellites

AbstractWe present geomagnetic main field and secular variation time series, at 300 equal-area distributed locations and at 490 km altitude, derived from magnetic field measurements collected by the three Swarm satellites. These Geomagnetic Virtual Observatory (GVO) series provide a convenient means to globally monitor and analyze long-term variations of the geomagnetic field from low-Earth orbit. The series are obtained by robust fits of local Cartesian potential field models to along-track and East–West sums and differences of Swarm satellite data collected within a radius of 700 km of the GVO locations during either 1-monthly or 4-monthly time windows. We describe two GVO data products: (1) ‘Observed Field’ GVO time series, where all observed sources contribute to the estimated values, without any data selection or correction, and (2) ‘Core Field’ GVO time series, where additional data selection is carried out, then de-noising schemes and epoch-by-epoch spherical harmonic analysis are applied to reduce contamination by magnetospheric and ionospheric signals. Secular variation series are provided as annual differences of the Core Field GVOs. We present examples of the resulting Swarm GVO series, assessing their quality through comparisons with ground observatories and geomagnetic field models. In benchmark comparisons with six high-quality mid-to-low latitude ground observatories we find the secular variation of the Core Field GVO field intensities, calculated using annual differences, agrees to an rms of 1.8 nT/yr and 1.2 nT/yr for the 1-monthly and 4-monthly versions, respectively. Regular sampling in space and time, and the availability of data error estimates, makes the GVO series well suited for users wishing to perform data assimilation studies of core dynamics, or to study long-period magnetospheric and ionospheric signals and their induced counterparts. The Swarm GVO time series will be regularly updated, approximately every four months, allowing ready access to the latest secular variation data from the Swarm satellites.

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