scholarly journals The new WMM2020 and IGRF-13 models, and a retrospective analysis of IGRF secular variation

2020 ◽  
Author(s):  
William Brown ◽  
Ciarán Beggan ◽  
Grace Cox ◽  
Susan Macmillan
Keyword(s):  
Retrospective Analysis ◽  
Secular Variation ◽  
Task Force ◽  
Reference Field ◽  
Coordinate Systems ◽  
International Geomagnetic Reference Field ◽  
The North ◽  
The Us ◽  
The World ◽  
Magnetic Model

<p>2020 marks the start of a new 5-year cycle and updated releases of the World Magnetic Model (WMM) and International Geomagnetic Reference Field (IGRF). These models provide a reference for the up-to-date internal geomagnetic field in 2020, and a prediction of its secular variation for the next 5 years, to 2025. While similar in some aspects, the two models have different specifications and many different users across diverse fields. They provide references to be used primarily for navigation (WMM) and geomagnetic coordinate systems (IGRF).</p><p>BGS produces the WMM in collaboration with the US’ NOAA/NCEI, while the IGRF is produced by an IAGA Div. V-MOD task force, this time consisting of fifteen teams across nine nations, including BGS. Here we present a summary of the production of the updated WMM2020 and IGRF-13, and BGS efforts to enable access to these models.</p><p>We also present a retrospective analysis of the predictive components of the candidate models for previous IGRF epoch’s secular variation. Recent epochs have seen notable geomagnetic jerks and the acceleration of the North magnetic dip pole, features not well represented by the constant SV format of models such as the IGRF. We assess the range of candidate models submitted for previous IGRF epochs, assess the accuracy of physically derived predictions versus mathematical extrapolations, and discuss the implications given the range of candidate models submitted for IGRF-13 secular variation over the next five years.</p>

scholarly journals Evaluation of candidate models for the 13th generation International Geomagnetic Reference Field

2020 ◽  
Author(s):  
Patrick Alken ◽  
Erwan Thebault ◽  
Ciaran Beggan ◽  
Julien Aubert ◽  
Julien Baerenzung ◽  
...  
Keyword(s):  
Secular Variation ◽  
Task Force ◽  
International Association ◽  
Research Centre ◽  
Reference Field ◽  
International Geomagnetic Reference Field ◽  
British Geological Survey ◽  
International Geomagnetic Reference ◽  
Geographical Regions ◽  
Weighted Model

Abstract In December 2019, the 13th revision of the International Geomagnetic Reference Field (IGRF) was released by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD. This revision comprises two new spherical harmonic main field models for epochs 2015.0 (DGRF-2015) and 2020.0 (IGRF-2020) and a model of the predicted secular variation for the interval 2020.0 to 2025.0 (SV-2020-2025). The models were produced from candidates submitted by fifteen international teams. These teams were led by the British Geological Survey (UK), China Earthquake Administration (China), Universidad Complutense de Madrid (Spain), University of Colorado Boulder (USA), Technical University of Denmark (Denmark), GFZ German Research Centre for Geosciences (Germany), Institut de physique du globe de Paris (France), Institut des Sciences de la Terre (France), Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (Russia), Kyoto University (Japan), University of Leeds (UK), Max Planck Institute for Solar System Research (Germany), NASA Goddard Space Flight Center (USA), University of Potsdam (Germany), and Universit\'e de Strasbourg (France). The candidate models were evaluated individually and compared to all other candidates as well to the mean, median and a robust Huber-weighted model of all candidates. These analyses were used to identify, for example, the variation between the Gauss coefficients or the geographical regions where the candidate models strongly differed. The majority of candidates were sufficiently close that the differences can be explained primarily by individual modeling methodologies and data selection strategies. None of the candidates were so different as to warrant their exclusion from the final IGRF-13. The IAGA V-MOD task force thus voted for two approaches: the median of the Gauss coefficients of the candidates for the DGRF-2015 and IGRF-2020 models and the robust Huber-weighted model for the predictive SV-2020-2025. In this paper, we document the evaluation of the candidate models and provide details of the approach used to derive the final IGRF-13 products. We also perform a retrospective analysis of the IGRF-12 SV candidates over their performance period (2015-2020). Our findings suggest that forecasting secular variation can benefit from combining physics-based core modeling with satellite observations.

scholarly journals Evaluation of candidate models for the 13th generation International Geomagnetic Reference Field

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
P. Alken ◽  
E. Thébault ◽  
C. D. Beggan ◽  
J. Aubert ◽  
J. Baerenzung ◽  
...  
Keyword(s):  
Secular Variation ◽  
Task Force ◽  
International Association ◽  
Research Centre ◽  
Reference Field ◽  
International Geomagnetic Reference Field ◽  
British Geological Survey ◽  
International Geomagnetic Reference ◽  
Geographical Regions ◽  
Weighted Model

AbstractIn December 2019, the 13th revision of the International Geomagnetic Reference Field (IGRF) was released by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD. This revision comprises two new spherical harmonic main field models for epochs 2015.0 (DGRF-2015) and 2020.0 (IGRF-2020) and a model of the predicted secular variation for the interval 2020.0 to 2025.0 (SV-2020-2025). The models were produced from candidates submitted by fifteen international teams. These teams were led by the British Geological Survey (UK), China Earthquake Administration (China), Universidad Complutense de Madrid (Spain), University of Colorado Boulder (USA), Technical University of Denmark (Denmark), GFZ German Research Centre for Geosciences (Germany), Institut de physique du globe de Paris (France), Institut des Sciences de la Terre (France), Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (Russia), Kyoto University (Japan), University of Leeds (UK), Max Planck Institute for Solar System Research (Germany), NASA Goddard Space Flight Center (USA), University of Potsdam (Germany), and Université de Strasbourg (France). The candidate models were evaluated individually and compared to all other candidates as well to the mean, median and a robust Huber-weighted model of all candidates. These analyses were used to identify, for example, the variation between the Gauss coefficients or the geographical regions where the candidate models strongly differed. The majority of candidates were sufficiently close that the differences can be explained primarily by individual modeling methodologies and data selection strategies. None of the candidates were so different as to warrant their exclusion from the final IGRF-13. The IAGA V-MOD task force thus voted for two approaches: the median of the Gauss coefficients of the candidates for the DGRF-2015 and IGRF-2020 models and the robust Huber-weighted model for the predictive SV-2020-2025. In this paper, we document the evaluation of the candidate models and provide details of the approach used to derive the final IGRF-13 products. We also perform a retrospective analysis of the IGRF-12 SV candidates over their performance period (2015–2020). Our findings suggest that forecasting secular variation can benefit from combining physics-based core modeling with satellite observations.

The World Economy

1997 ◽  
Vol 159 ◽  
pp. 28-56
Author(s):  
Julian Morgan ◽  
Nigel Pain ◽  
Florence Hubert
Keyword(s):  
World Trade ◽  
World Economy ◽  
Fiscal Consolidation ◽  
The Third ◽  
The North ◽  
External Demand ◽  
The Us ◽  
The World ◽  
World Economic ◽  
The Uk

There are now widespread signs that activity in the world economy has begun to recover steadily from the pause in growth apparent at the beginning of 1996. Output rose by 0.6 per cent in the North American economies in the third quarter of last year and by 0.8 per cent in Europe. Business and consumer sentiment has improved gradually in recent months in most of the major economies. We expect world economic growth to pick up further over the course of this year as the contractionary effects from the downturn in world trade and prolonged inventory adjustment come to an end and as the effects from a more relaxed monetary stance begin to outweigh those from ongoing fiscal consolidation. Recent currency movements should help to stimulate external demand in Germany, France and Japan, but may act to constrain growth within the UK, Italy and the US. For both this year and 1998 we expect growth of around 2½ per cent per annum in the OECD economies.

scholarly journals Geomagnetic core field models and secular variation forecasts for the 13th International Geomagnetic Reference Field (IGRF-13)

2020 ◽  
Author(s):  
Ingo Wardinski ◽  
Diana Saturnino ◽  
Hagay Amit ◽  
Aude Chambodut ◽  
Benoit Langlais ◽  
...  
Keyword(s):  
Secular Variation ◽  
Geomagnetic Field ◽  
Singular Spectrum Analysis ◽  
Reference Field ◽  
Candidate Model ◽  
Main Field ◽  
International Geomagnetic Reference Field ◽  
Core Field ◽  
International Geomagnetic Reference ◽  
Continuous Models

Abstract Observations of the geomagnetic field taken at Earth's surface and at satellite altitude were combined to construct continuous models of the geomagnetic field and its secular variation from 1957 to 2020. From these parent models, we derive candidate main field models for the epochs 2015 and 2020 to the 13th generation of the International Geomagnetic Reference Field (IGRF). The secular variation candidate model for the period 2020 - 2025 is derived from a forecast of the secular variation in 2022.5, which results from a multi-variate singular spectrum analysis of the secular variation from 1957 to 2020.

Asia in 2019

Asian Survey ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 1-7
Author(s):  
Uk Heo
Keyword(s):  
Hong Kong ◽  
Policy Implications ◽  
The North ◽  
China Trade ◽  
The Us ◽  
The World ◽  
Nuclear Issue ◽  
Trade War ◽  
Economic Partnership ◽  
Regional Comprehensive Economic Partnership

Among the major events that occurred in Asia in 2019 were four that received global attention: the Regional Comprehensive Economic Partnership (RCEP), the US-China trade war, the North Korean nuclear issue, and protests in Hong Kong. These events have significant policy implications for the world as well as for Asia.

International Geomagnetic Reference Field 1980 A Report by IAGA Division I, Working Group I

Geophysics ◽  
1982 ◽  
Vol 47 (5) ◽  
pp. 841-842 ◽  
Author(s):  
Norman W. Peddie
Keyword(s):  
Secular Variation ◽  
Working Group ◽  
Field Model ◽  
International Association ◽  
Division I ◽  
Reference Field ◽  
Main Field ◽  
International Geomagnetic Reference Field ◽  
International Geomagnetic Reference ◽  
Group I

IGRF 1965, the first international geomagnetic reference field, was adopted by the International Association of Geomagnetism and Aeronomy (IAGA) in 1968 (IAGA Commission 2, Working Group 4, 1969). It consists of a model of the main field at 1965.0, along with a model of secular variation for use in extending the main field model in time, both backward (not earlier than 1955.0) and forward (not later than 1975.0). IGRF 1975, adopted later, consists of IGRF 1965 extended to 1975.0, along with a revised model of secular variation for use in extending the main field model up to 1980.0 (IAGA Division I Study Group, 1976).

International Geomagnetic Reference Field Revision 1987

Geophysics ◽  
1988 ◽  
Vol 53 (4) ◽  
pp. 576-578 ◽  
Author(s):  
D. R. Barraclough
Keyword(s):  
Charged Particle ◽  
Mathematical Models ◽  
Secular Variation ◽  
Spherical Harmonic ◽  
Geomagnetic Field ◽  
Magnetic Anomalies ◽  
Reference Field ◽  
International Geomagnetic Reference Field ◽  
International Geomagnetic Reference ◽  
Field Revision

The International Geomagnetic Reference Field (IGRF) is a series of mathematical models of the main geomagnetic field and its secular variation, the models consisting of sets of spherical harmonic (or Gauss) coefficients. The IGRF has become a widely used means of deriving values of geomagnetic field components in, for example, studies of magnetic anomalies and investigations of charged particle motions in the ionosphere and the magnetosphere.

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