Indicators of mantle control on the geodynamo from observations and simulations
There has been longstanding controversy about whether the influence of lateral variations in core-mantle boundary heat flow can be detected in paleomagnetic records of geomagnetic field behavior. Their signature is commonly sought in globally distributed records of virtual geomagnetic pole (VGP) pat...
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Frontiers Media S.A.
2022-08-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2022.957815/full |
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| author | Monika Korte Catherine G. Constable Christopher J. Davies Sanja Panovska |
| author_facet | Monika Korte Catherine G. Constable Christopher J. Davies Sanja Panovska |
| author_sort | Monika Korte |
| collection | DOAJ |
| description | There has been longstanding controversy about whether the influence of lateral variations in core-mantle boundary heat flow can be detected in paleomagnetic records of geomagnetic field behavior. Their signature is commonly sought in globally distributed records of virtual geomagnetic pole (VGP) paths that have been claimed to exhibit specific longitudinal preferences during polarity transitions and excursions. These preferences have often been linked to thermal effects from large low seismic velocity areas (LLVPs) in the lowermost mantle, but the results have been contested because of potential sensitivity to sparse temporal and spatial sampling. Recently developed time varying global paleofield models spanning various time intervals in 1–100 ka, three of which include excursions, allow us to complement assessments of spatial distributions of transitional VGP paths with distributions of minimum field intensity. Robustness of the results is evaluated using similar products from four distinct numerical dynamo simulations with and without variable thermal boundary conditions and including stable geomagnetic polarity, excursions and reversals. We determine that VGP distributions are less useful than minimum field intensity in linking the influences of thermal CMB structure to geographical variations in actual paleofield observables, because VGP correlations depend strongly on good spatial sampling of a sufficient number of relatively rare events. These results provide a basis for evaluating comparable observations from four paleofield models. The distribution of VGP locations provide unreliable results given the restricted time span and available data locations. Rough correlations of global distributions of minimum intensity with areas outside the LLVPs give some indications of mantle control during excursions, although the results for the eastern hemisphere are complex, perhaps highlighting uncertainties about the hemispheric balance between thermal and compositional variations in the lowermost mantle. However, access to other geomagnetic properties (such as intensity and radial field at the CMB) provides a strong argument for using extended and improved global paleofield models to resolve the question of mantle influence on the geodynamo from the observational side. |
| first_indexed | 2024-04-11T09:41:01Z |
| format | Article |
| id | doaj.art-70fd9cb897c7419daaa594992e85a107 |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-04-11T09:41:01Z |
| publishDate | 2022-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-70fd9cb897c7419daaa594992e85a1072022-12-22T04:31:11ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632022-08-011010.3389/feart.2022.957815957815Indicators of mantle control on the geodynamo from observations and simulationsMonika Korte0Catherine G. Constable1Christopher J. Davies2Sanja Panovska3Helmholtz Zentrum Potsdam, Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, GermanyInstitute for Geophsysics and Planetary Physics, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA, United StatesSchool of Earth and Environment, University of Leeds, Leeds, United KingdomHelmholtz Zentrum Potsdam, Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, GermanyThere has been longstanding controversy about whether the influence of lateral variations in core-mantle boundary heat flow can be detected in paleomagnetic records of geomagnetic field behavior. Their signature is commonly sought in globally distributed records of virtual geomagnetic pole (VGP) paths that have been claimed to exhibit specific longitudinal preferences during polarity transitions and excursions. These preferences have often been linked to thermal effects from large low seismic velocity areas (LLVPs) in the lowermost mantle, but the results have been contested because of potential sensitivity to sparse temporal and spatial sampling. Recently developed time varying global paleofield models spanning various time intervals in 1–100 ka, three of which include excursions, allow us to complement assessments of spatial distributions of transitional VGP paths with distributions of minimum field intensity. Robustness of the results is evaluated using similar products from four distinct numerical dynamo simulations with and without variable thermal boundary conditions and including stable geomagnetic polarity, excursions and reversals. We determine that VGP distributions are less useful than minimum field intensity in linking the influences of thermal CMB structure to geographical variations in actual paleofield observables, because VGP correlations depend strongly on good spatial sampling of a sufficient number of relatively rare events. These results provide a basis for evaluating comparable observations from four paleofield models. The distribution of VGP locations provide unreliable results given the restricted time span and available data locations. Rough correlations of global distributions of minimum intensity with areas outside the LLVPs give some indications of mantle control during excursions, although the results for the eastern hemisphere are complex, perhaps highlighting uncertainties about the hemispheric balance between thermal and compositional variations in the lowermost mantle. However, access to other geomagnetic properties (such as intensity and radial field at the CMB) provides a strong argument for using extended and improved global paleofield models to resolve the question of mantle influence on the geodynamo from the observational side.https://www.frontiersin.org/articles/10.3389/feart.2022.957815/fullcore-mantle boundarypaleomagnetic field modelsgeomagnetismgeodynamoLLVPs |
| spellingShingle | Monika Korte Catherine G. Constable Christopher J. Davies Sanja Panovska Indicators of mantle control on the geodynamo from observations and simulations Frontiers in Earth Science core-mantle boundary paleomagnetic field models geomagnetism geodynamo LLVPs |
| title | Indicators of mantle control on the geodynamo from observations and simulations |
| title_full | Indicators of mantle control on the geodynamo from observations and simulations |
| title_fullStr | Indicators of mantle control on the geodynamo from observations and simulations |
| title_full_unstemmed | Indicators of mantle control on the geodynamo from observations and simulations |
| title_short | Indicators of mantle control on the geodynamo from observations and simulations |
| title_sort | indicators of mantle control on the geodynamo from observations and simulations |
| topic | core-mantle boundary paleomagnetic field models geomagnetism geodynamo LLVPs |
| url | https://www.frontiersin.org/articles/10.3389/feart.2022.957815/full |
| work_keys_str_mv | AT monikakorte indicatorsofmantlecontrolonthegeodynamofromobservationsandsimulations AT catherinegconstable indicatorsofmantlecontrolonthegeodynamofromobservationsandsimulations AT christopherjdavies indicatorsofmantlecontrolonthegeodynamofromobservationsandsimulations AT sanjapanovska indicatorsofmantlecontrolonthegeodynamofromobservationsandsimulations |