The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecasts
Abstract The three candidate models submitted by the British Geological Survey for the 13th generation International Geomagnetic Reference Field are described. These DGRF and IGRF models are derived from vector and scalar magnetic field data from the European Space Agency Swarm satellites and ground...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2021-02-01
|
| Series: | Earth, Planets and Space |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40623-020-01301-3 |
| _version_ | 1818957783340417024 |
|---|---|
| author | William J. Brown Ciarán D. Beggan Grace A. Cox Susan Macmillan |
| author_facet | William J. Brown Ciarán D. Beggan Grace A. Cox Susan Macmillan |
| author_sort | William J. Brown |
| collection | DOAJ |
| description | Abstract The three candidate models submitted by the British Geological Survey for the 13th generation International Geomagnetic Reference Field are described. These DGRF and IGRF models are derived from vector and scalar magnetic field data from the European Space Agency Swarm satellites and ground observatories, covering the period 2013.9 to 2019.7. The internal field model has time dependence for degrees 1 to 15, represented by order 6 B-splines with knots at six monthly intervals. We also solve for a degree 1 external field time dependence describing annual and semi-annual signals with additional dependence on a bespoke Vector Magnetic Disturbance index. Satellite data are weighted by spatial density, along-track standard deviations, and a larger-scale noise estimator defined in terms of a measure of Local Area Vector Activity at the geographically closest magnetic observatories to the sampled datum. Forecasting of the magnetic field secular variation for 2020–2025 is by advection of the main field using steady core surface flows with steady acceleration applied. We also investigate the performance of the previous generation of candidate secular variation models, for IGRF-12, analysing the agreement of the candidates between 2015 and 2020 with the retrospective IGRF-13. We find that there is no clear distinction between the performance of mathematically and physically extrapolated forecasts in the period 2015–2020. We confirm that the methodology for the BGS IGRF-12 predictions performed well, despite observed secular accelerations that are highlighted by our analysis, and thus justify the methodology used for our IGRF-13 SV candidate. |
| first_indexed | 2024-12-20T11:15:20Z |
| format | Article |
| id | doaj.art-bed032adac154e7ebaea840c1c1519c9 |
| institution | Directory Open Access Journal |
| issn | 1880-5981 |
| language | English |
| last_indexed | 2024-12-20T11:15:20Z |
| publishDate | 2021-02-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Earth, Planets and Space |
| spelling | doaj.art-bed032adac154e7ebaea840c1c1519c92022-12-21T19:42:39ZengSpringerOpenEarth, Planets and Space1880-59812021-02-0173112110.1186/s40623-020-01301-3The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecastsWilliam J. Brown0Ciarán D. Beggan1Grace A. Cox2Susan Macmillan3British Geological Survey, The Lyell CentreBritish Geological Survey, The Lyell CentreBritish Geological Survey, The Lyell CentreBritish Geological Survey, The Lyell CentreAbstract The three candidate models submitted by the British Geological Survey for the 13th generation International Geomagnetic Reference Field are described. These DGRF and IGRF models are derived from vector and scalar magnetic field data from the European Space Agency Swarm satellites and ground observatories, covering the period 2013.9 to 2019.7. The internal field model has time dependence for degrees 1 to 15, represented by order 6 B-splines with knots at six monthly intervals. We also solve for a degree 1 external field time dependence describing annual and semi-annual signals with additional dependence on a bespoke Vector Magnetic Disturbance index. Satellite data are weighted by spatial density, along-track standard deviations, and a larger-scale noise estimator defined in terms of a measure of Local Area Vector Activity at the geographically closest magnetic observatories to the sampled datum. Forecasting of the magnetic field secular variation for 2020–2025 is by advection of the main field using steady core surface flows with steady acceleration applied. We also investigate the performance of the previous generation of candidate secular variation models, for IGRF-12, analysing the agreement of the candidates between 2015 and 2020 with the retrospective IGRF-13. We find that there is no clear distinction between the performance of mathematically and physically extrapolated forecasts in the period 2015–2020. We confirm that the methodology for the BGS IGRF-12 predictions performed well, despite observed secular accelerations that are highlighted by our analysis, and thus justify the methodology used for our IGRF-13 SV candidate.https://doi.org/10.1186/s40623-020-01301-3International Geomagnetic Reference FieldGeomagnetismSecular variation |
| spellingShingle | William J. Brown Ciarán D. Beggan Grace A. Cox Susan Macmillan The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecasts Earth, Planets and Space International Geomagnetic Reference Field Geomagnetism Secular variation |
| title | The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecasts |
| title_full | The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecasts |
| title_fullStr | The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecasts |
| title_full_unstemmed | The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecasts |
| title_short | The BGS candidate models for IGRF-13 with a retrospective analysis of IGRF-12 secular variation forecasts |
| title_sort | bgs candidate models for igrf 13 with a retrospective analysis of igrf 12 secular variation forecasts |
| topic | International Geomagnetic Reference Field Geomagnetism Secular variation |
| url | https://doi.org/10.1186/s40623-020-01301-3 |
| work_keys_str_mv | AT williamjbrown thebgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts AT ciarandbeggan thebgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts AT graceacox thebgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts AT susanmacmillan thebgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts AT williamjbrown bgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts AT ciarandbeggan bgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts AT graceacox bgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts AT susanmacmillan bgscandidatemodelsforigrf13witharetrospectiveanalysisofigrf12secularvariationforecasts |