ITalian Geomagnetic Reference Field (ITGRF): update for 2000 and secular variation model up to 2005 by autoregressive forecasting

The updated version of the ITalian Geomagnetic Reference Field (ITGRF) for 2000.0 and its secular variation model up to 2005.0 are presented in this paper. The main field model is based on a simple polynomial approximation in latitude and longitude of the geomagnetic field elements computed from IGRF on a 12° ¥ 11° grid centred over Italy. The annual means from L'Aquila observatory were used to determine the baseline level, imposing a constant observatory anomaly bias. This procedure gives a set of 6 coefficients every 5 years from 1960 to 2005 for the horizontal H, total field F, vertical Z and declination D elements of the geomagnetic field. The extrapolation of ITGRF to 2005 is based on an autoregressive forecasting of the L'Aquila observatory annual means. Comparison of the field values computed from the model with those recorded at the other Italian observatory (Castello Tesino) shows that the ITGRF improves the fit of the secular variation pattern with respect to the global IGRF model by a factor of 3. The ITGRF represents a reliable alternative to global models when reducing magnetic surveys to a common reference epoch over the Italian region

Variaciones geomagnéticas de origen ionosférico en días de calma

[EN] Recent progress in the study of the quiet-day geomagnetic field variations having the ionosphere as a source is reviewed. This represents an old topic in the history of Geomagnetism and Aeronomy, and since the purpose of the paper is to provide the reader with an overall description of its present understanding, no matter whether a particular subtopic has been revisited in the last decade or not, the degree of updating is variable throughout the review. Special attention is paid to the advances in the modeling techniques and to the possible explanations to the variability of the mid-latitude ionospheric current system.[ES] En este artículo se examinan los avances recientes en el estudio de las variaciones geomagnéticas que tienen su origen en la ionosfera en situaciones de ausencia de perturbaciones magnéticas. Este es un antiguo tema en la historia del Geomagnetismo y la Aeronomía, y como el artículo pretende proporcionar una visión de conjunto de su conocimiento actual, sin importar si una disciplina en particular se ha investigado o no en la última década, el grado de actualización es variable a lo largo de la revisión. Se pone una atención especial en las técnicas de modelización y en las posibles explicaciones a la variabilidad día a día del sistema de corrientes ionosférico en latitudes medias.Peer reviewe

An evaluation of the uncertainty associated with the measurement of the geomagnetic field with a D/I fluxgate theodolite

14 pages, 12 figures, 2 tables.-- Printed version published Jul 2007.An analysis of the sources of uncertainty in measuring the angular elements of the geomagnetic field with the D/I fluxgate theodolite on the basis of the Guide to the Expression of Uncertainty in Measurement published by the International Organization for Standardization is presented. Along with the uncertainty associated with random effects, the habitual measurement procedure evidences the existence of systematic effects that are often ignored in the daily observatory practice. Special emphasis has been put on the development of a plausible theoretical scheme to explain the origin of such effects, and a series of procedures are proposed to find their actual sources as well as several recommendations with the final aim to improve the accuracy of the observations. Other effects, which strictly do not seem to suit the traditional classification into either systematic or random, are also analysed. Some of the results obtained have been applied to the absolute instruments in use at the Livingston Island Geomagnetic Observatory and at certain European observatories. Systematic contributions to uncertainty are difficult to outline in a general case, since they depend on each particular instrument. On the other hand, an accurate estimation of the uncertainty associated with random effects has been obtained, concluding that their magnitude does not generally exceed 0.1 arcmin for an experienced observer, for either declination or inclination.Peer reviewe

Una visión sobre el estado actual de la investigación en geomagnetismo

5 págs, 4 figs.En este artículo se examinan los avances recientes en el ámbito general del geomagnetismo, una de las Ciencias de la Tierra con una más larga historia, seguramente por la importancia que ha tenido para la navegación. La revisión se ha dividido en cuatro grandes áreas y en diversas subdisciplinas dentro de las mismas, finalizando con una visión sobre las posibles líneas de evolución que se auguran para algunas de ellas.Peer reviewe

An Assessment of the BGS δDδI Vector Magnetometer

Assuming optimal conditions, the δDδI vector magnetometer can be considered as a semi-absolute instrument. In this paper, the real situation and its differences with the ideal one are critically examined and regarded as potential sources of error. The analysis is applied to the equipment designed by the British Geological Survey (BGS) in the late 1980s, and the given figures are provided from the instrument in use at the Livingston Island Geomagnetic Observatory (LIV). Improved versions have been developed since then, being based on generally the same principles of measurement; thus, most of the results shown can be adapted to the new generation of magnetometers of this type.Peer reviewe

La investigación polar como motor de la innovación tecnológica

Curso Observando los polos: pasado, presente y futuro, organizado por la Plataforma Temática Interdisciplinar (PTI) POLARCSIC en colaboración con la Universidad Internacional Menéndez Pelayo (UIMP) y celebrado del 4 al 8 de noviembre de 2019 en Barcelona.-- Mesa redonda moderada por Jordi FelipePeer reviewe

The Ebre Observatoty in Antacrctica

Poster presentado en: International Workshop "Challenges for Geomagnetism Aeronomy and Seismology in the XXI Century: on the occasion of the Centennial Of Ebro Observatory". Roquetes (Tarragona), España. 29 september - 10 October 2004.Since 1996 Ebre Observatory is monitoring and studying the geomagnetic field not only in Spain but also in Antarctica. In this poster, a brief introdution to LIV Observatory characteristics and instruments is given, together with some experimental results and related models, obtained from the analysis of its data. Regional and continental magnetic studies have also been developed to compile and analyze marine and aeromagnetic anomaly data in the South Shetland Islands -Bransfield Strait- Antarctic Peninsula region, and to produce a main field plus secular variation geomagnetic reference model valid from 1960 onwards.Peer reviewe

Automatic measurement of magnetic records on photographic paper

Final full-text version of the paper available at: http://www.sciencedirect.com/science/journal/00983004Measuring and storing magnetometer data recorded photographically is a difficult problem for a geomagnetic observatory. In the Ebre Observatory, to overcome the problem, we have developed a system using modern computing advances which include electronic scanning, storage on CD-ROM media, and image analysis. This paper describes the main processes performed by this system. In particular, it describes the main difficulties found in the process of digitization (intersections, gaps,…) and how they were solved.Authors thank the collaboration of the Juan Salañer Foundation and the C.E.T.S. of the Institut Químic de Sarrià, and recognize the contribution of J. Mustany and R. Gené, the true pioneers of this work.Peer reviewe