Produção acadêmica-PPGFA

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Ahead-of-Tsunami magnetic disturbance detection using intrinsic mode functions: Tohoku-Oki earthquake case study
(Springer Nature Link) Oliveira, Virgínia Klausner de; Macedo, Humberto Gimenes; Prestes, Alan
We document magnetic disturbances that occurred during the Tohoku-Oki tsunami of 11 March 2011 using empirical mode decomposition (EMD) in a dataset derived from a network of ground-based magnetometers (INTERMAGNET and GIS). The disturbances, obtained by filtering the magnetic field data using the first intrinsic mode function (IMF1) of EMD, propagate ahead of the tsunami at a speed in the range of 600–1.6 km/s. They also appear 3 min (near-field) to 2 h (far-field) earlier than the tsunami arrival at the magnetic observatories. We refer to these distur- bances as ahead-of-tsunami magnetic disturbances (ATMDs). A comparison with seismometer data shows them arriving 10 min after the arrival of Rayleigh waves. Their association with both seismogenic and tsunamigenic processes is discussed, and it is argued that the tsunamigenic process can well explain the magnetic disturbance propagation characteristics at the far-field. At near- field, the ATMDs are the coseismic magnetic signatures mainly driven by surface Rayleigh waves. Monitoring these ATMDs can be extremely useful for the early warning of the tsunami.
Análise de componentes principais aplicada à dendrocronologia
Silva, Daniela Oliveira da; Oliveira, Virgínia Klausner de; Prestes, Alan; Macedo, Humberto Gimenes
Climate Influence in Dendrochronological Series of Araucaria angustifolia from Campos do Jordão, Brazil
(MDPI) Silva, Daniela Oliveira da; Prestes, Alan; Klausner, Virginia; Souza, Táyla Gabrielle Gonçalves de
A dendrochronological series of Araucaria angustifolia was analyzed for a better under- standing of the climatic factors that operate in Campos do Jordão city, São Paulo state, Brazil. The dendroclimatic analysis was carried out using 45 samples from 16 Araucaria angustifolia trees to recon- struct the precipitation and the temperature over the 1803–2012 yearly interval. To this end, Pearson’s correlation was calculated between mean chronology and the climatic time series using a monthly temporal resolution to calibrate our models. We obtained correlations as high as r = 0.22 (α = 0.1) for precipitation (February), and r = 0.21 (α = 0.1) for temperature (March), both corresponding to the end of the summer season. Our results show evidence of temporal instabilities because the corre- lations for the halves of 1963–2012 were very different, as well as for the full period. To overcome this problem, the dendrochronological series and the climatic data were investigated using the wavelet techniques searching for time-dependent cause–effect relationships. From these analyses, we find a strong influence of the region’s precipitation and temperature on the growth of tree ring widths.
Contextualização e interdisciplinaridade: revisando conceitos e aplicações no ensino de física e ciências
(Universidade do Vale do Paraíba) Fernandes, Francisco Carlos Rocha; Prestes, Alan
O ensino da disciplina de Física se baseia, muitas vezes, na apresentação dos conteúdos, conceitos e leis físicas de forma mecânica e fragmentada, além de distanciada das experiências e vivências prévias dos alunos. Em oposição a essa realidade, os documentos oficiais, que norteiam a educação no país, como os Parâmetros Curriculares Nacionais (PCN), apontam, entre outras concepções metodológicas, a contextualização e a interdisciplinaridade do conhecimento como abordagens educacionais facilitadoras de uma aprendizagem, na qual, educadores e alunos são agentes ativos na construção do conhecimento. Neste artigo, é apresentada uma revisão da literatura dos conceitos de contextualização e interdisciplinaridade no ensino de Física do Ensino Médio e de Ciências no Ensino Fundamental, com o objetivo de melhor entender seu importante papel nas propostas e ações de ensino-aprendizagem, que privilegiam um conhecimento contextualizado e integrado à vida do educando. Relatos de experiências bem-sucedidas na adoção destas concepções são também apresentados e comentados.
Enhancing learning of the Grad-Shafranov Equation through scientific literature: part 1 of a physics education series
(Sociedade Brasileira de Física) Ojeda González, Arian; Santos, Lenadro Nunes dos; La Luz, Victor Hugo de; Oliveira, Matheus Felipe Cristaldo de; Sousa, Antonio Nilson Laurindo; Prestes, Alan; Klausner, Virgínia; Pilling, Sergio
This article provides a comprehensive review of relevant studies in the fields of plasma physics, electromagnetism, and space physics. The aim is to demonstrate how the study of the scientific literature can be used to enhance problem-solving abilities and develop innovative solutions in physics. In this paper, we focus on the study of solutions of the specific Grad-Shafranov equation. Two of the new solutions proposed by Yoon and Lui (2005) are used as a basis for the development of a new solution. The new solution presented has singular points similar to the Yoon-Lui-2 solution, but with an inverted configuration, and also presents less rounded double islands compared to the Yoon-Lui-2 solution. Additionally, the new solution does not exhibit the formation of a current ring, a characteristic of the Yoon-Lui-1 solution, and varying its parameters may lead to higher plasma confinement efficiency. In summary, we illustrate how a thorough analysis of literature can serve as a powerful means for generating innovative approaches to resolving theoretical issues in physics.
Enhancing learning of the Grad-Shafranov equation through scientific literature: part 2 of a physics education series
(Sociedade Brasileira de Física) Santos, Lenadro Nunes dos; Ojeda González, Arian; La Luz, Victor Hugo de; Oliveira, Virgínia Klausner de; Pilling, Sergio; Prestes, Alan; Sousa, Antonio Nilson Laurindo; Oliveira, Matheus Felipe Cristaldo de
In part 1 of our physics education series, we introduced a novel solution based on Yoon-Lui’s solutions 1 and 2. Building upon that, this follow-up presents a new solution obtained by combining the generating functions of Yoon-Lui-1 and Yoon-Lui-3, resulting in a new and simplified general solution. We also calculate the singular points and determine their coordinates for various parameter values. A graphical representation of the solution is presented, showing the magnetic field lines and current density distribution. The behavior of the magnetic field and the effect of varying the parameter are discussed. The observed magnetic islands and singular points are relevant in the fields of Plasma Physics and Space Physics, providing insights into magnetic structures in plasmas and their impact on confinement and stability. Furthermore, this study encourages innovation and equips researchers and students with the necessary tools to make meaningful contributions to the field, emphasizing the integration of scientific literature into physics education to promote a comprehensive understanding of physical concepts and their practical applications.
Exploring patterns in dendrochronological data through cluster analysis
(Universidade Federal do Paraná) Muraja, Daniela Oliveira Silva; Leite, Cecília Lemes; Klausner, Virginia; Prestes, Alan; Silva, Iuri Rojahn da
This study employed the dendrogram methodology to analyze time series data obtained from measuring tree growth rings. A total of 64 samples were collected from 21 individual trees. Polynomials were applied to filter the natural growth pattern of the trees and enhance the impact of external factors, such as climate influences. Cluster analysis using Ward's minimum variance and Euclidean squared distance was utilized to group the data based on similarity. Three dendrograms were constructed, consisting of 10, 47, and 64 samples, respectively. The analysis revealed that the samples with the highest correlations, encompassing over 95% of the total samples, formed homogeneous groups. Pearson correlation was also employed to confirm the results obtained from the dendrograms. Consequently, it can be affirmed that the most suitable samples were utilized in constructing the average chronology from the available data.
Exploring the centennial-scale climate history of Southern Brazil with Ocotea porosa (Nees & Mart.) Barroso Tree-Rings
(MDPI) Muraja, Daniela Oliveira Silva; Klausner, Virginia; Prestes, Alan; Aakala, Tuomas; Macedo, Humberto Gimenes; Silva, Iuri Rojahn da
This article explores the dendrochronological potential of Ocotea porosa (Nees & Mart) Barroso (Imbuia) for reconstructing past climate conditions in the General Carneiro region, Southern Brazil, utilizing well-established dendroclimatic techniques. A total of 41 samples of Imbuia were subjected to dendroclimatic analysis to reconstruct precipitation and temperature patterns over the period from 1446 to 2011. Notably, we achieved the longest reconstructions of spring precipitation and temperature for the Brazilian southern region, spanning an impressive 566-year timeframe, by employing a mean chronology approach. To achieve our objectives, we conducted a Pearson’s correlation analysis between the mean chronology and the climatic time series, with a monthly temporal resolution employed for model calibration. Impressively, our findings reveal significant correlations with coefficients as high as |rx,P| = 0.32 for precipitation and |rx,T| = 0.45 for temperature during the spring season. Importantly, our climate reconstructions may elucidate a direct influence of the El Niño—South Oscillation phenomenon on precipitation and temperature patterns, which, in turn, are intricately linked to the natural growth patterns of the Imbuia trees. These results shed valuable light on the historical climate variability in the Southern Brazil region and provide insights into the climatic drivers affecting the growth dynamics of Ocotea porosa (Nees & Mart) Barroso.
Geomagnetic Disturbances During the Maule (2010) Tsunami Detected by Four Spatiotemporal Methods
(Springer Nature Link) Klausner, Virginia; Macedo, Humberto Gimenes; Cezarini, Marina Vedelago; Ojeda-González, Arian; Prestes, Alan; Cândido, Claudia Maria Nicoli; Kherani, Esfhan Alam; Santos, Thiago de Almeida
Separating tsunamigenic variations in geomagnetic field measurements in the presence of more dominant magnetic variations by magnetospheric and ionospheric currents is a challenging task. The purpose of this article is to survey the tsunamigenic variations in the vertical component (Z) and the horizontal component (H) of the geomagnetic field using four spatiotemporal methods. Spatiotemporal analysis has shown enormous potential and efficiency in retrieving tsunamigenic contributions from geomagnetic field measurements. We select the Maule (2010) tsunami event on the west coast of Chile and examine the geomagnetic measurements from 13 ground magnetometers scattered in the Pacific Ocean covering a wide area from Chile, crossing the Pacific Ocean to Japan. The tsunamigenic magnetic disturbances are possibly due to two types of contributions, one arising from direct ocean motion and the other from atmospheric motion, both associated with tsunami forcing. Moreover, even though the tsunami waves decrease considerably with increasing epicentral distance, the tsunamigenic contributions are retrieved from a magnetic observatory in Australia ( 13,000 km radial distance from the epicenter). These results suggest that various types of tsunamigenic disturbances can be identified well from the integrated analysis framework presented in this work.
Identificação e análise de eventos HILDCAA/HILDCAA* para o ano de 1998 usando Python
(Universidade do Vale do Paraíba) Lamin, Isabelle Cristine Pellegrini; Klausner, Virginia; Ojeda González, Arian; Prestes, Alan; Pillat, Valdir Gil; Cezarini, Marina
O artigo visa o desenvolvimento de um novo algoritmo via Python para estudar eventos de Atividade Auroral Contínua do Índice AE (Eletrojato Auroral), de Grande Intensidade e Longa Duração, HILDCAAs e HILDCAAs* (no qual * corresponde ao fenômeno HILDCAA flexibilizado). Este algoritmo é baseado e validado por meio do algoritmo previamente desenvolvido por Prestes et al. (2017a) em MATLAB. O intuito deste novo algoritmo proposto aqui é tornar o fluxograma deste acessível a todos os usuários, além de complementar e atualizar o algoritmo em MATLAB já existente. Um importante aspecto é o fato da linguagem de programação de alto nível Python ser uma ferramenta gratuita. Ademais, o artigo também objetiva a comparação dos eventos encontrados no ano de 1998 neste trabalho com aqueles obtidos por Prestes et al. (2017a) e Guarnieri (2006). A nova flexibilização adotada aqui não tem a intensão de suprimir ou modificar a concepção original das HILDCAAs, mostra que os eventos encontrados aqui continuam associados aos fenômenos HSSs/CIRs (Feixes Rápidos do Vento Solar/Regiões de Interações Corrotantes).
Influence of Climate and Solar Variability on Growth Rings of Araucaria angustifolia in Três Barras National Forest (Brazil)
(MDPI) Muraja, Daniela Oliveira Silva; Klausner, Virginia; Prestes, Alan; Silva, Aline Conceicao da; Lemes, Cecilia Leite
This research applies continuous wavelet analysis and seasonal correlation anal- ysis to tree-ring data from Três Barras National Forest (FLONA Três Barras), revealing diverse influences on growth, including climate, solar activity, and external factors. The methodology involved tree-ring collection and subsequent wavelet and seasonal analy- ses to unveil the non-stationary characteristics of and multifaceted influences on growth. Key findings include the subtle effects of El Niño events on tree-ring development, the sensitivity of Araucaria angustifolia to temperature changes, the significant influence of precipitation during drought periods, and the intricate relationship between tree growth and solar cycles. The El Niño–Southern Oscillation (ENSO) emerges as a primary climatic driver during specific intervals, with external factors (precipitation, temperature, and solar cycle–solar irradiance) influencing tree response between 1936 and 1989. Additionally, the seasonal correlation analysis highlighted the importance of sub-annual climate variability, capturing specific intervals, such as a 3-month season ending in March of the previous year, that significantly impacted tree-ring growth. The study underscores the importance of protecting the endangered Araucaria angustifolia for climatic studies and local commu- nities. Historically, in Brazil, Araucaria angustifolia seeds played a vital role in sustaining indigenous populations, which in turn helped to disperse and propagate forests, creating anthropogenic landscapes that highlight the interconnected relationship between humans and the preservation of these forests.
Ocean–atmosphere interaction identified in tree-ring time series from southern Brazil using cross-wavelet analysis
(Springer Nature Link) Muraja, Daniela Oliveira Silva; Klausner, Virginia; Prestes, Alan; Silva, Iuri Rojahn da
Tropical dendrochronology has gained significant attention in recent years, particularly with the dendrochronological study of new species that produce annual growth rings and are responsive to environmental changes. Despite the progress, the extent to which ocean–atmosphere interactions influence regional climate and, consequently, tree growth, is not fully understood. Among the new species, Ocotea porosa (Nees & Mart.) Barroso (also known as Imbuia) has shown excellent potential for climate research. This study investigates the climatic and solar influences on a chronology of 41 Imbuia tree samples. Pearson’s correlation was used alongside Wavelet transform to evaluate periodicities between the tree-ring chronology and climatic parameters such as the southern-oscillation index (SOI), annual precipitation, El Niño 3.4 (PACE), and the South Atlantic Index (ATLS). Our analysis revealed evidence of the influence of the El Niño Southern Oscillation (SOI) on rainfall variability in the region, the Hale and Gleissberg solar cycles causing precipitation variation, likely due to the influence of the Atlantic Ocean, and the Brückner-Egeson-Lockyer climatic cycle, which is correlated with sunspot activity. Furthermore, our wavelet analysis identified possible connections to the Eastern Pacific-type El Niño events during five specific periods: 1911–1912, 1918–1919, 1976–1977, 1982–1983, and 1986–1987. The results indicate that southern Brazil is affected by several climatic and geophysical parameters from both the Atlantic and Pacific oceans, which directly affect the growth of Imbuia trees as their tree-ring series display sensitivity to these parameters.
Principal component analysis applied to dendrochronology
(Universidade Federal do Rio Grande do Norte) Silva, Daniela Oliveira da; Klausner, Virginia; Prestes, Alan; Macedo, Humberto Gimenes
This work uses samples of the species Ocotea porosa (Nees & Mart) Barroso (Imbuia), collected in the city of General Carneiro, Southeast region of the State of Paraná (26o24'01 25"S 51o24'03 91"W), Brazil, to generate average chronology (GC index) of this region. The objective of this article is to remove the natural growth trends of trees using a tool that is still little explored for this purpose, Principal Component Analysis (PCA). In each tree sample, the width of each growth ring was measured, obtaining a time series (1 ring per year). The samples were selected using Cluster Analysis, which classifies samples based on their similarities. Once the Principal Components (PCs) were obtained, the dendrochronological series were reconstructed without the first PC. This methodology is an estimate of the trend that best represents the natural growth of all trees on the site. The arithmetic mean of the series without the 1st PC is the GC index. It was found that PCA has three benefits: fast data processing, preservation of low-frequency signals and, when integrated with a powerful tool, the Alternated Least Squares (ALS) method, missing data estimation.
Principal component analysis in the modeling of HILDCAAs during the Solar Minimum of Cycle 23/24
(Elsevier) Klausner, Virginia; Lamin, Isabelle Cristine Pellegrini; Ojeda-González, Arian; Macedo, Humberto Gimenes; Cândido, Claudia Maria Nicoli; Prestes, Alan; Cezarini, Marina Vedelago
In this article, we propose a new approach to model the high-intensity, long-duration, continuous AE (Auroral Electrojet) activity (HILDCAA) by relaxing one of the criteria originally designed, based on the interplanetary features during the unusual Solar Minimum of Cycle 23/24 (SMC23/24). This relaxation does not intend to suppress or modify the original HILDCAAs’ conception, but propose a new view of the same phenomena by enlarging the sample of events, which in turn may improve space weather monitoring and prediction programs. To assess and classify the Alfvénity associated with HILDCAAs, the values of 4h-Windowed Pearson Cross-Correlation (4WPCC) between the IMF components and the solar wind speed components observed in situ at the Lagrangian point L1 (1 AU) were evaluated. The principal component analysis (PCA) was performed on the dataset and, from the first three principal components, which represent 65% of the accumulative percent variance, we applied principal component regression (PCR) in each of the following parameters: the AE index, the Interplanetary Magnetic Field (IMF) components, the plasma density, the solar wind speed, the temperature, the IMF magnitude, and the SYM-H geomagnetic index. Furthermore, we applied Multiple Linear Regression (MLR) to establish a linear model to express the AE index in terms of the PCR-based model parameters. The AE MLR-based model demonstrated to hold a prognosis potential for HILDCAAs. Despite that, this model is only suitable for the SMC23/24. In this sense, this model might be implemented a real-time analysis for short-term HILDCAA prognosis in the near future.
Principal Components Analysis: An Alternative Way for Removing Natural Growth Trends
(Springer Nature Link) Silva, Daniela Oliveira da; Klausner, Virginia; Prestes, Alan; Macedo, Humberto Gimenes; Aakala, Tuomas; Silva, Iuri Rojahn da
In this article, we establish a new approach for removing natural growth trends from tree-ring samples, also called detrending. We demonstrate this approach using Ocotea porosa (Nees & Mart) Barroso trees. Nondestructive samples were collected in General Carneiro city, located in the Brazilian southern region (Paraná state). To remove natural tree growth trends, principal components analysis (PCA) was applied on the tree-ring series as a new detrending method. From this, we obtained the tree-ring indices by reconstructing the tree-ring series without the first principal component (PC), which we expect to represent the natural growth trend. The performance of this PCA method was then compared to other detrending methods commonly used in dendrochronology, such as the cubic spline method, negative exponential or linear regression curve, and the regional curve standardization method. A comparison of these methods showed that the PCA detrending method can be used as an alternative to traditional methods since (1) it preserves the low-frequency variance in the 566-year chronology and (2) represents an automatic way to remove the natural growth trends of all individual measurement series at the same time. Moreover, when implemented using the alternating least squares (ALS) method, the PCA can deal with tree-ring series of different lengths.

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