TY - JOUR
T1 - A geomagnetic field model for the Holocene based on archaeomagnetic and lava flow data
AU - Pavón-Carrasco, Francisco Javier
AU - Osete, María Luisa
AU - Torta, Joan Miquel
AU - De Santis, Angelo
N1 - Funding Information:
We are very grateful for the comments of the associate Editor Dr. Dennis Kent; and for the reviews of Dr. Richard Holme and a second, anonymous referee, who both helped to improve the final manuscript. The authors are grateful to the Spanish research project CGL2011-24790 of the Spanish Ministerio de Economía y Competitividad. They are also grateful to all the archaeomagnetic and palaeomagnetic community for the effort of providing the archaeo-palaeomagnetic data and the construction of useful databases. F.J. Pavón-Carrasco acknowledges the ME/Fulbright postdoctoral contract CT-2010-0663 and the Fundación Española para la Ciencia y la Tecnología (FECYT). He also thanks the INGV-Roma High-Performance Computing team.
PY - 2014/2/15
Y1 - 2014/2/15
N2 - We propose a new geomagnetic field model for the Holocene period based on archaeomagnetic and lava flow data, avoiding the use of lake sediment data. The source of data comes from the GEOMAGIA50v2 database which has been updated with the new archaeomagnetic and volcanic studies published during the last 3 yr. The model, called SHA.DIF.14k, allows us to analyse the behaviour of the geomagnetic field for the last 14000 yr: from 12000 BC to 1900 AD. For the model construction we use the spherical harmonic analysis in space and the penalized cubic B-splines in time. Both spatial and temporal regularization norms are used to constrain the inversion problem and applied at the core-mantle boundary (CMB) to assure the convergence of the model. For the last 3 ka, the model predictions agree with those given by the global model ARCH3k.1 and the European model SCHA.DIF.3k. For older epochs, the new model presents a clear improvement in field resolution with respect to other current models of the geomagnetic field for the Holocene. For the last 9 ka, the time evolution of the dipolar moment obtained from the dipole field shows a clear minimum between 5500 BC and 3000 BC, and the well-known continuous decreasing trend of the geomagnetic field strength for the last millennium and a half. A general view of the time-average evolution of the geomagnetic field flux lobes at the CMB for the northern hemisphere suggests a marked lobe of positive magnetic flux when the dipole moment was maximum. This lobe vanishes when the dipolar field is decreasing. The north polar wander paths of both north magnetic dip and geomagnetic poles were obtained showing an average rate of motion of 5.1 km/yr and 3.7 km/yr respectively. The model shows that the geomagnetic field can be averaged as axial dipolar in ~2000yr within an error of 5°, the typical uncertainty of the palaeomagnetic studies. Finally, and following the recent definition of archaeomagnetic jerks, we found 8 critical events in the time evolution of the geomagnetic field for the last 8 ka characterized by a maximum in the hemispheric asymmetry of the proposed model. The model is available in the Earth Ref Digital Archive at http://earthref.org/ERDA/1897/.
AB - We propose a new geomagnetic field model for the Holocene period based on archaeomagnetic and lava flow data, avoiding the use of lake sediment data. The source of data comes from the GEOMAGIA50v2 database which has been updated with the new archaeomagnetic and volcanic studies published during the last 3 yr. The model, called SHA.DIF.14k, allows us to analyse the behaviour of the geomagnetic field for the last 14000 yr: from 12000 BC to 1900 AD. For the model construction we use the spherical harmonic analysis in space and the penalized cubic B-splines in time. Both spatial and temporal regularization norms are used to constrain the inversion problem and applied at the core-mantle boundary (CMB) to assure the convergence of the model. For the last 3 ka, the model predictions agree with those given by the global model ARCH3k.1 and the European model SCHA.DIF.3k. For older epochs, the new model presents a clear improvement in field resolution with respect to other current models of the geomagnetic field for the Holocene. For the last 9 ka, the time evolution of the dipolar moment obtained from the dipole field shows a clear minimum between 5500 BC and 3000 BC, and the well-known continuous decreasing trend of the geomagnetic field strength for the last millennium and a half. A general view of the time-average evolution of the geomagnetic field flux lobes at the CMB for the northern hemisphere suggests a marked lobe of positive magnetic flux when the dipole moment was maximum. This lobe vanishes when the dipolar field is decreasing. The north polar wander paths of both north magnetic dip and geomagnetic poles were obtained showing an average rate of motion of 5.1 km/yr and 3.7 km/yr respectively. The model shows that the geomagnetic field can be averaged as axial dipolar in ~2000yr within an error of 5°, the typical uncertainty of the palaeomagnetic studies. Finally, and following the recent definition of archaeomagnetic jerks, we found 8 critical events in the time evolution of the geomagnetic field for the last 8 ka characterized by a maximum in the hemispheric asymmetry of the proposed model. The model is available in the Earth Ref Digital Archive at http://earthref.org/ERDA/1897/.
KW - Archaeomagnetism
KW - Geomagnetic field model
KW - Geomagnetism
KW - Holocene
KW - Secular variation
UR - http://www.scopus.com/inward/record.url?scp=84890622762&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2013.11.046
DO - 10.1016/j.epsl.2013.11.046
M3 - Article
AN - SCOPUS:84890622762
SN - 0012-821X
VL - 388
SP - 98
EP - 109
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
ER -