Science CONOPS for Application of SPORT Mission Data to Study Large (~1000km) Ionospheric Plasma Depletions

The Scintillation Prediction Observations Research Task (SPORT) mission is a single 6U CubeSat space weather satellite planned for an October 2022 launch into an ISS-like orbit. The primary purpose of the SPORT mission is to determine the longitudinal effects on equatorial plasma bubble (EPB) growth resulting from the offset dipole magnetic field of the Earth. By combining field and plasma measurements from SPORT with other low-altitude (i.e., alt \u3c 1000 km) spacecraft, it is possible to investigate large-scale (\u3e 1000 km) EPB structures. The types of investigation made possible by measurements from SPORT and other contemporaneous missions include 1) dynamics of depleted magnetic flux tubes; 2) dynamics of field-aligned EPB expansion versus propagation speed; 3) EPB vertical extent; and 4) EPB temporal evolution. To support these investigation types, the respective modes of conjunctions are: 1) simultaneous intersection of a magnetic flux tube; 2) intersection of magnetic flux tube separated in time; 3) Simultaneous Latitude/Longitude position conjunction; and 4) Non-simultaneous latitude/longitude position conjunction. This paper will summarize the SPORT satellite and data used for Science CONOPS to accomplish these objectives

Estudo experimental de distorções geradas por linhas férreas eletrificadas em sondagens magnetotelúricas

Foram realizadas sondagens magnetotelúricas (MT) em perfis ortogonais a Estrada de Ferro Campos do Jordão (EFCJ) na faixa de períodos de 20 a 6000 s. Os perfis situam-se nos estados de São Paulo e Minas Gerais, em duas regiões de condutividade contrastantes: a Bacia de Taubaté, região sedimentar, e a Serra da Mantiqueira, região cristalina. A EFCJ opera com corrente elétrica DC produzindo um ruído eletromagnético (EM) intenso, mas apenas no período diurno, sendo desativada a noite. Objetiva-se com este trabalho caracterizar o ruído EM produzido pela EFCJ e verificar seu efeito sobre os parâmetros MT. Com este intuito, os dados diurnos e noturnos foram analisados separadamente, enfatizando assim os efeitos da presença ou ausência do ruído. Para a estimação do tensor de impedância (Z), foram utilizadas diversas técnicas disponíveis a comunidade científica e, dos resultados obtidos, foi calculada a resistividade aparente e fase. Fez-se a comparação entre os métodos procurando estabelecer a melhor abordagem para a obtenção de parâmetros MT confiáveis. Verificou-se, como esperado, que a presença do ruído torna as curvas de resistividade aparente e fase mais irregulares e com barras de erros maiores. No entanto, para os métodos que obtiveram resultados satisfatórios, nota-se que os valores obtidos entre os períodos com e sem ruídos são praticamente os mesmos. Conclui-se que, para estes métodos e na faixa de frequência trabalhada, os dados podem ser analisados como um todo, sem que com isto o período contaminado com o ruído venha a mascarar o resultado, e com a vantagem de obter-se um resultado estatístico melhor, por aumentar a série temporal analisada. ABSTRACT: Magnetotelluric soundings (MT) were carried out on profiles orthogonal to the Campos do Jordao Railway (EFCJ) in the period range of 20 to 6000 s. The profiles were located at São Paulo and Minas Gerais States, on two adjacent regions with contrasting conductivity: the conductive sedimentary region of Taubaté Basin and the resistive crystalline region of Serra da Mantiqueira. The EFCJ operates with DC current that produces an intense electromagnetic (EM) noise, but only during diurnal periods, being turned off at night. The objective of this study is to characterize the EM noise made by the EFCJ and to verify its effects on MT parameters. Thus, the diurnal and nocturnal data were analyzed separately, and then compared in order to observe the effects of the noise. Some techniques presently available to the scientific community were used to estimate the impedance tensor (Z) and then the apparent resistivity and phase were calculated. The comparison between methods was used to establish the best way to obtain trustworthy MT parameters. As expected, the noise produced more irregular plots of apparent resistivity and phase and greater error bars. Nevertheless, for the methods that produced reliable results, the values obtained on the periods with and without the noise are practically the same. Then, for these methods, and in the studied frequency band, all data could be used in the analyzes, because the contaminated periods did not produce screening effects, with the advantage of providing a better statistical results with the increase in the analyzed time series.Number of Pages: 7

Magnetotelluric deep soundings, gravity and geoid in the south São Francisco craton: Geophysical indicators of cratonic lithosphere rejuvenation and crustal underplating

In the south São Francisco craton a circular and 8-m amplitude geoid anomaly coincides with the outcropping terrain of an ArcheanPaleoproterozoic basement. Broadband magnetotelluric (MT) data inversions of two radial profiles within the positive geoid and Bouguer gravity anomaly yield geo-electrical crustal sections, whereby the lower crust is locally more conductive (10 to 100 Ωm) in spatial coincidence with a denser lower crust modeled by the gravity data. This anomalous lower crust may have resulted from magmatic underplating, associated with Mesoarchean and Proterozoic episodes of tholeiitic dike intrusion. Long-period MT soundings reveal a low electrical resistivity mantle (20 to 200 Ωm) from depths beyond 120 km. Forward geoid modeling, using the scope of the low electrical resistivity region within the mantle as a constraint, entails a density increase (40 to 50 kg/m3) possibly due to Fe enrichment of mantle minerals. However, this factor alone does not explain the observed resistivity. A supplemented presence of small amounts of percolated carbonatite melting (~0.005 vol.%), dissolved water and enhanced oxygen fugacity within the peridotitic mantle are viable agents that could explain the less resistive upper mantle. We propose that metasomatic processes confined in the sub-continental lithospheric mantle foster the conditions for a low degree melting with variable CO2, H2O and Fe content. Even though the precise age of this metasomatism is unknown it might be older than the Early Cretaceous based on the evidence that a highdegree of melting in a lithospheric mantle impregnated with carbonatites originated the tholeiitic dike intrusions dispersed from the southeastern border of the São Francisco craton, during the onset of the lithosphere extension and break-up of the western Gondwana. The proxies are the NE Paraná and Espinhaço (130 Ma, Ar/Ar ages) tholeiitic dikes, which contain (~3%) carbonatites in their composition. The occurrence of a positive geoid anomaly (+10 m) and pre-tholeiites (ageN138 Ma), carbonatites and kimberlites along the west African continental margin (Angola and Namibia) reinforces the presumed age of the São FranciscoCongo craton rejuvenation to be prior to its fragmentation in the Lower Cretaceous.Pages: 423-43