GEOMAGIA50: An archeointensity database with PHP and MySQL

Korhonen, Kimmo; Donadini, F.; Riisager, Peter; Pesonen, L. J.

doi:10.1029/2007gc001893

Cited by 112 publications

(98 citation statements)

References 25 publications

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“…In order to detect the regional variations of the geomagnetic field in Eastern Asia, we compare our new results with the published data from China and Japan compiled in the GEOMAGIA50 database (Donadini et al, 2006;Korhonen et al, 2008) (Fig. 6).…”

Section: Discussionmentioning

confidence: 99%

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Cai

Tauxe

Deng

et al. 2014

Earth and Planetary Science Letters

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In this study, we have carried out paleointensity experiments on 918 specimens spanning the last ∼7 kyr, including pottery fragments, baked clay and slag, collected from Shandong, Liaoning, Zhejiang and Hebei Provinces in China. Approximately half of the specimens yielded results that passed strict data selection criteria and give high-fidelity paleointensities. The virtual axial dipole moments (VADMs) of our sites range from ∼2 × 10 22 to ∼13 × 10 22 Am 2 . At ∼2250 BCE our results suggest a paleointensity low of ∼2 × 10 22 Am 2 , which increases to a high of ∼13 × 10 22 Am 2 by ∼1300 BCE. This rapid (less than 1000 yrs) six-fold change in the paleointensity may have important implications for the dynamics of core flow at this time. Our data from the last ∼3 kyr are generally in good agreement with the ARCH3k.1 model, but deviate significantly at certain time periods from the CALS3k.4 and CALS10k.1b model, which is likely due to differences in the data used to constrain these models. At ages older than ∼3 ka, where only the CALS10k.1b model is available for comparison, our data deviate significantly from the model. Combining our new results with the published data from China and Japan, we provide greatly improved constraints for the regional model of Eastern Asia. When comparing the variations of geomagnetic field in three global representative areas of Eastern Asia, the Middle East and Southern Europe, a common general trend of sinusoidal variations since ∼8 ka is shown, likely dominated by the dipole component. However, significant disparities are revealed as well, which we attribute to non-dipolar components caused by movement of magnetic flux patches at the core-mantle boundary.

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Section: Discussionmentioning

confidence: 99%

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Cai

Tauxe

Deng

et al. 2014

Earth and Planetary Science Letters

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“…Here we used the GEOMAGIA50.v3 database (Donadini et al 2006;Korhonen et al 2008;Brown et al 2015) to which we added recent archeo-and paleointensity results (Cai et al 2014(Cai et al , 2015Cromwell et al 2015;de Groot et al 2015;Di Chiara et al 2014;Gallet et al 2008Gallet et al , 2009Gallet & Al Maqdissi 2010;Hong et al 2013;Kapper et al 2015;Kissel et al 2015;Osete et al 2015;Shaar et al 2015;Stillinger et al 2015). Concerning the data compiled in this version of GEOMAGIA, the Mesopotamian data from Nachasova & Burakov (1995 were modified according to .…”

Section: Appendix A: Gmag9k Axial Dipole Evolutionmentioning

confidence: 99%

Solar activity during the Holocene: the Hallstatt cycle and its consequence for grand minima and maxima

Usoskin

Gallet

Lopes

et al. 2016

A&A

136

183

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Aims. Cosmogenic isotopes provide the only quantitative proxy for analyzing the long-term solar variability over a centennial timescale. While essential progress has been achieved in both measurements and modeling of the cosmogenic proxy, uncertainties still remain in the determination of the geomagnetic dipole moment evolution. Here we aim at improving the reconstruction of solar activity over the past nine millennia using a multi-proxy approach. Methods. We used records of the 14 C and 10 Be cosmogenic isotopes, current numerical models of the isotope production and transport in Earth's atmosphere, and available geomagnetic field reconstructions, including a new reconstruction relying on an updated archeo-and paleointensity database. The obtained series were analyzed using the singular spectrum analysis (SSA) method to study the millennial-scale trends. Results. A new reconstruction of the geomagnetic dipole field moment, referred to as GMAG.9k, is built for the last nine millennia. New reconstructions of solar activity covering the last nine millennia, quantified in terms of sunspot numbers, are presented and analyzed. A conservative list of grand minima and maxima is also provided. Conclusions. The primary components of the reconstructed solar activity, as determined using the SSA method, are different for the series that are based on 14 C and 10 Be. This shows that these primary components can only be ascribed to long-term changes in the terrestrial system and not to the Sun. These components have therefore been removed from the reconstructed series. In contrast, the secondary SSA components of the reconstructed solar activity are found to be dominated by a common ≈2400-year quasi-periodicity, the so-called Hallstatt cycle, in both the 14 C and 10 Be based series. This Hallstatt cycle thus appears to be related to solar activity. Finally, we show that the grand minima and maxima occurred intermittently over the studied period, with clustering near lows and highs of the Hallstatt cycle, respectively.

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“…Korte et al 2005;Donadini et al 2006;Genevey et al 2008;Korhonen et al 2008). The most up to date compilation is provided by the GEOMAGIA50.v3 database (Brown et al 2015a,b).…”

Section: Introductionmentioning

confidence: 99%

The HISTMAG database: combining historical, archaeomagnetic and volcanic data

Arneitz

Leonhardt

Schnepp³

et al. 2017

Geophysical Journal International

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S U M M A R YRecords of the past geomagnetic field can be divided into two main categories. These are instrumental historical observations on the one hand, and field estimates based on the magnetization acquired by rocks, sediments and archaeological artefacts on the other hand. In this paper, a new database combining historical, archaeomagnetic and volcanic records is presented. HISTMAG is a relational database, implemented in MySQL, and can be accessed via a web-based interface (http://www.conrad-observatory.at/zamg/index.php/data-en/histmag-database). It combines available global historical data compilations covering the last ∼500 yr as well as archaeomagnetic and volcanic data collections from the last 50 000 yr. Furthermore, new historical and archaeomagnetic records, mainly from central Europe, have been acquired. In total, 190 427 records are currently available in the HISTMAG database, whereby the majority is related to historical declination measurements (155 525). The original database structure was complemented by new fields, which allow for a detailed description of the different data types. A user-comment function provides the possibility for a scientific discussion about individual records. Therefore, HISTMAG database supports thorough reliability and uncertainty assessments of the widely different data sets, which are an essential basis for geomagnetic field reconstructions. A database analysis revealed systematic offset for declination records derived from compass roses on historical geographical maps through comparison with other historical records, while maps created for mining activities represent a reliable source.

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GEOMAGIA50: An archeointensity database with PHP and MySQL

Cited by 112 publications

References 25 publications

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Solar activity during the Holocene: the Hallstatt cycle and its consequence for grand minima and maxima

The HISTMAG database: combining historical, archaeomagnetic and volcanic data

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