Person: Osete López, María Luisa
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First Name
María Luisa
Last Name
Osete López
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de la Tierra y Astrofísica
Area
Física de la Tierra
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Eccentric Dipole Evolution during the Last Reversal, Last Excursions, and Holocene Anomalies. Interpretation Using a 360-Dipole Ring Model(Geosciences, 2021) González López, Alicia; Osete López, María Luisa; Arquero Campuzano, Saioa; Molina Cardín, Alberto; Rivera Pérez, Pablo; Pavón Carrasco, Francisco JavierThe eccentric dipole (ED) is the next approach of the geomagnetic field after the generally used geocentric dipole. Here, we analyzed the evolution of the ED during extreme events, such as the Matuyama-Brunhes polarity transition (~780 ka), the Laschamp (~41 ka) and Mono Lake (~34 ka) excursions, and during the time of two anomalous features of the geomagnetic field observed during the Holocene: the Levantine Iron Age Anomaly (LIAA, ~1000 BC) and the South Atlantic Anomaly (SAA, analyzed from ~700 AD to present day). The analysis was carried out using the paleoreconstructions that cover the time of the mentioned events (IMMAB4, IMOLEe, LSMOD.2, SHAWQ-Iron Age, and SHAWQ2k). We found that the ED moves around the meridian plane of 0–180◦ during the reversal and the excursions; it moves towards the region of the LIAA; and it moves away from the SAA. To investigate what information can be extracted from its evolution, we designed a simple model based on 360-point dipoles evenly distributed in a ring close to the inner core boundary that can be reversed and their magnitude changed. We tried to reproduce with our simple model the observed evolution of the ED, and the total field energy at the Earth’s surface. We observed that the modeled ED moves away from the region where we set the dipoles to reverse. If we consider that the ring dipoles could be related to convective columns in the outer core of the Earth, our simple model would indicate the potential of the displacement of the ED to give information about the regions in the outer core where changes start for polarity transitions and for the generation of important anomalies of the geomagnetic field. According to our simple model, the regions in which the most important events of the Holocene occur, or in which the last polarity reversal or excursion begin, are related to the regions of the Core Mantle Boundary (CMB), where the heat flux is low.Item Non-dipole and regional effects on the geomagnetic dipole moment estimation(Pure and Applied Geophys, 2015) Arquero Campuzano, Saioa; Pavón Carrasco, Francisco Javier; Osete López, María LuisaThe study of the temporal evolution of the dipole moment variations is a forefront research topic in Earth sciences. It constrains geodynamo simulations and is used to correct cosmogenic isotope production, which is evidence of past solar activity, and it is used to study possible correlations between the geomagnetic field and the climate. In this work, we have analysed the main error sources in the geomagnetic dipole moment computation from palaeomagnetic data: the influence of the non-dipole terms in the average approach, the inhomogeneous distribution of the current palaeomagnetic database, and the averaging procedure used to obtain the evolution of the dipole moment. To evaluate and quantify these effects, we have used synthetic data from a global model based on instrumental and satellite data, the International Geomagnetic Reference Field: 11th generation. Results indicate that the non-dipole terms contribute on a global scale of < 6 % in the averaged dipole moment, whereas the regional non-dipole contribution can show deviations of up to 35 % in some regions such as Oceania, and different temporal trends with respect to the global dipole moment evolution in other ones, such as Europe and Asia. A regional weighting scheme seems the best option to mitigate these effects in the dipole moment average approach. But when directional and intensity palaeomagnetic information is available on a global scale, and in spite of the inhomogeneity of the database, global modelling presents more reliable values of the geomagnetic dipole moment.Item New perspectives in the study of the Earth's magnetic field and climate connection: the use of transfer entropy(PLOS one, 2018) Pavón Carrasco, Francisco Javier; Osete López, María Luisa; Arquero Campuzano, Saioa; De Santis, Angelo; Qamili, EnkelejdaThe debated question on the possible relation between the Earth's magnetic field and climate has been usually focused on direct correlations between different time series representing both systems. However, the physical mechanism able to potentially explain this connection is still an open issue. Finding hints about how this connection could work would suppose an important advance in the search of an adequate physical mechanism. Here, we propose an innovative information-theoretic tool, i.e. the transfer entropy, as a good candidate for this scope because is able to determine, not simply the possible existence of a connection, but even the direction in which the link is produced. We have applied this new methodology to two real time series, the South Atlantic Anomaly (SAA) area extent at the Earth's surface (representing the geomagnetic field system) and the Global Sea Level (GSL) rise (for the climate system) for the last 300 years, to measure the possible information flow and sense between them. This connection was previously suggested considering only the long-term trend while now we study this possibility also in shorter scales. The new results seem to support this hypothesis, with more information transferred from the SAA to the GSL time series, with about 90% of confidence level. This result provides new clues on the existence of a link between the geomagnetic field and the Earth's climate in the past and on the physical mechanism involved because, thanks to the application of the transfer entropy, we have determined that the sense of the connection seems to go from the system that produces geomagnetic field to the climate system. Of course, the connection does not mean that the geomagnetic field is fully responsible for the climate changes, rather that it is an important driving component to the variations of the climate.Item Multi-centennial fluctuations of radionuclide production rates are modulated by the Earth's magnetic field(Scientific reports, 2018) Pavón Carrasco, Francisco Javier; Gómez Paccard, M.; Arquero Campuzano, Saioa; González Rouco, Jesús Fidel; Osete López, María LuisaThe production of cosmogenic isotopes offers a unique way to reconstruct solar activity during the Holocene. It is influenced by both the solar and Earth magnetic fields and thus their combined effect needs to be disentangled to infer past solar irradiance. Nowadays, it is assumed that the long-term variations of cosmogenic production are modulated by the geomagnetic field and that the solar field dominates over shorter wavelengths. In this process, the effects of the non-dipolar terms of the geomagnetic field are considered negligible. Here we analyse these assumptions and demonstrate that, for a constant solar modulation potential, the geomagnetic field exerts a strong modulation of multi-centennial to millennial wavelengths (periods of 800 and 2200 yr). Moreover, we demonstrate that the non-dipole terms derived from the harmonic degree 3 and above produce maximum differences of 7% in the global average radiocarbon production rate. The results are supported by the identification, for the first time, of a robust coherence between the production rates independently estimated from geomagnetic reconstructions and that inferred from natural archives. This implies the need to review past solar forcing reconstructions, with important implications both for the assessment of solar-climate relationships as well as for the present and future generation of paleoclimate models.Item Characteristic periods of the paleosecular variation of the Earth's magnetic field during the Holocene from global paleoreconstructions(Physics of the earth and planetary interiors, 2021) González López, Alicia; Arquero Campuzano, Saioa; Molina Cardín, Alberto; Pavón Carrasco, Francisco Javier; De Santis, A.; Osete López, María LuisaThe knowledge of the secular variation of the geomagnetic field at different time scales is important to determine the mechanisms that maintain the geomagnetic field and can help to establish constraints in dynamo theories. We have focused our study on the secular variation at millennial and centennial time scale searching for characteristic periods during the last 10 kyr. The frequency study was performed using four recent updated global paleomagnetic field reconstructions (SHA.DIF.14k, CALS10k.2, BIGMUDI4k and SHAWQ2k) by applying three techniques commonly used in signal analysis: the Fourier transform, the Empirical Mode Decomposition, and the wavelet analysis. Short-term variability of the geomagnetic field energy shows recurrent periods of around 2000, 1000–1400, and 600–800 and 250–400 years. The characteristic time around 600–800 years is well determined in all paleomagnetic reconstructions and it is mostly related to the axial dipole and axial octupole terms, but also observable in the equatorial dipole. In addition to this period, longer characteristic times of around 1000–1400 years are found particularly in the equatorial dipole and quadrupole terms in SHA.DIF.14k, CALS10k.2 and BIGMUDI4k while the 2000 year period is only well determined in the total geomagnetic field energy of SHA. DIF.14k and CALS10k.2. The most detailed paleoreconstructions for younger times also detect shortest characteristic times of around 250–400 years. The long-term variation of the geomagnetic energy is only observable in the axial dipole. A characteristic period of around 7000 years in both SHA.DIF.14k and CALS10k.2 has been found. This long period is related to two decays in the dipole field and a period of increasing intensity. The oldest decay took place between 7000 BCE and 4500 BCE and the present decay that started around 100 BCE. We have modeled the 4500 BCE up to present variation as a combination of a continuous decay, representing the diffusion term of the geomagnetic field, and one pulse that reinforces the strength of the field. Results show a characteristic diffusion time of around 11,000–15,000 years, which is compatible with the diffusion times of the dipole field used in geodynamo theories.Item Updated Iberian archeomagnetic catalogue: new full vector Paleosecular variation curve for the last three millennia(Geochemistry, Geophysics, Geosystems, 2018) Molina Cardín, Alberto; Osete López, María Luisa; Pavón Carrasco, Francisco Javier; Palencia Ortas, Alicia; Martín Hernández, Fátima; Guerrero Suárez, Sara; Pérez Fuentes, J. C.; Arquero Campuzano, Saioa; Rivero Montero, M.; Gómez Paccard, M.Plain language summary In this work, we present 16 directional and 27 intensity high-quality values from Iberia. Moreover, we have updated the Iberian archeomagnetic catalogue published more than 10years ago with a considerable increase in the database. This has led to a notable improvement of both temporal and spatial data distribution. A full vector paleosecular variation curve from 1000 BC to 1900 AD has been developed using high-quality data within a radius of 900km from Madrid. A hierarchical bootstrap method has been followed for the computation of the curves. The most remarkable feature of the new curves is a notable intensity maximum of about 80T around 600 BC, which has not been previously reported for the Iberian Peninsula. We have also analyzed the evolution of the paleofield in Europe for the last three thousand years and conclude that the high maximum intensity values observed around 600 BC in the Iberian Peninsula could respond to the same feature as the Levantine Iron Age Anomaly, after travelling westward through Europe. Knowledge of the Earth's magnetic field plays an important role on the understanding of its dynamics. By measuring certain rocks or archeological objects from around the world, we can determine the field's shape and intensity in former times. Knowing its evolution is essential to understand how this field is generated, how it has varied through time and how it may behave in the future. In this work, we present new measurements of the magnetic field from the Iberian Peninsula that provide useful constraints on the magnetic field for archeological times that currently lack information. We have updated the compilation of Iberian data for the last 3,000years and calculated a new reference curve for the magnetic field for this region. We have found that the magnetic field was particularly intense in the Iberian Peninsula about 2,600 years ago. By comparing this result with data from Europe and the Middle East, we observe that this high intensity has been moving from east to west through southern Europe. This feature is probably related with the rapid intensity change (the geomagnetic spike) recently discovered in the Levantine region.- Project number: 44
Item Geofísica-SMART: Simples experiMentos de enseñanza apRendizaje en entoRnos digiTales(2022) Martín Hernández, Fátima; Ledo Fernandez, Juan José; Negredo Moreno, Ana María; Pavón Carrasco, Francisco Javier; Fullea Urchulutegui, Javier; Osete López, María Luisa; Ruíz Martínez, Vicente Carlos; Arquero Campuzano, Saioa; Llanes Estrada, María Pilar; Druet Vélez, María; Valles-Iriso, Javier; Gómez-Paccard, Miriam; Bonilla Alba, Raquel; Rivera Pérez, Pablo; López Sánchez, CarolinaLa Geofísica es una disciplina asociada a la Física experimental con gran desarrollo en multitud de ámbitos que van desde la arqueología a diferentes areas de la ingeniería como la geotécnia, ingeniería de minas o ingeniería geológica o bien el ámbito académico. Precisa de un conocimiento Físico de las leyes de la naturaleza pero también una destreza asociada a la Física más aplicada con multitud de experimentos en campo. Éstos son a veces difíciles de encontrar en libros de texto que se centran en los aspectos teóricos de la disciplina. Por eso, este proyecto pretende hacer ver a los estudiantes el diseño, desarrollo y procesado de experiencias de Geofísica Aplicada o prospectiva dentro de su desarrollo curricular.