MÉTODOS PARA INSTALAÇÃO E PROCESSAMENTO DE DADOS DO NOVO OBSERVATÓRIO MAGNÉTICO DO PANTANAL.

Abstract

The Earth magnetic field varies in a broad temporal scale, from milliseconds to millions of years. The field we measure at the surface results from the combination between different sources in the ionosphere, magnetosphere and the Earth´s core. The main field (or core field) is generated by a geodynamo process that has a nearly dipolar geometry with intensities varying from about 70.000 nT near the poles and about half of this value close to the equator. Magnetic observatories are fundamental for studies of those different sources, providing high accuracy measurements of the geomagnetic field components during long periods. The greater limitation of observatories is their distribution around the globe, mainly in South America and Africa, where there are only few data available. The two main objectives of this master thesis were: (i) the installation of the new magnetic observatory in Pantanal, following the methodology proposed by IAGA (International Association of Geomagnetism and Aeronomy) and (ii) data analysis of Pantanal magnetic station. The location of this new observatory is interesting for geomagnetism because of the presence of the South Atlantic Magnetic Anomaly (SAMA) that is the region with lowest intensity of the magnetic field in the globe. The SAMA is caused by dynamic processes in the core, but there are many open questions about its temporal evolution and its causes. SAMA has effects in the external field, especially during geomagnetic storms, and may cause problems in satellites, navigation systems and radio communication. This kind of disturb may be stronger in areas where the field intensity is weak (as in the SAMA) or high (as close to the geomagnetic poles). The data recorded in Pantanal will contribute for a better understanding about AMAS and its effects on the external field. This thesis describes all the steps for the installation of magnetic observatories. The main steps completed during this thesis were: selection of an appropriated area free from magnetic disturbance, gradiometry measurements in the selected area to avoid possible anomalies and tests on the materials to be used in the construction's house. In order to train the local staff in Pantanal and future observatories, a manual of absolute measurements was developed. During the field work done in Pantanal, a magnetic station was installed and measured the magnetic field for about four months. The aim was to analyse the temporal evolution of the total magnetic field (F). Two magnetic storms happened in this period: the first on the 24th and 25th October of 2011 and the second between the 21st and 24th January of 2012. These storms were classified using magnetic indices, compared with other observatories and analyzed using wavelet analysis to detect the sudden commencement of each storm and their duration. We aim in the future to use the data of new Brazilian observatories to built an alarm system for geomagnetic storms using the methodology applied for calculating magnetic indices.