Alan Prestes

Universidade do Vale do Paraíba | univap · Física e Astronomia

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...

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 precipitati...

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...

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...

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...

Este trabalho utiliza amostras da espécie Imbuia, (Ocotea porosa (Nees & Mart) Barroso), coletadas na cidade de General Carneiro, região Sudeste do Estado do Paraná (26º24’01 25"S 51º24’03 91"O), Brasil, para gerar a série dendrocronológica desta região. As amostras selecionadas para este estudo foram obtidas por meio de Análise de Clusters, que cl...

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, propag...

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...

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)...

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...

A dendrochronological series of Araucaria angustifolia was analyzed for a better understanding 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 reconstruct the precipitation and the temperature over the 1803–20...

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 o...

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 desenvolvid...

We report a study of the particulate matter emissions related to the 2015 fire outbreak at a fuel tank storage facility located at Santos, a coastal city in Brazil. The facility, managed by the company Ultracargo, had oil tanks (filled with gasoline and ethanol) destroyed by fire that lasted more than a week, between 2nd and 9th April. In this arti...

This article aims to present a theoretical formulation in the area of plasma physics to obtain a specific form of the Grad-Shafranov equation, in other words, to obtain the Ampère-Maxwell law as a function of the magnetic vector potential and current density. We seek to better understand some phenomena that occur in interplanetary plasma. Another o...

Amostras do lenho de Araucaria angustifolia coletadas em Painel, no estado de Santa Catarina, foram analisadas em comparação com séries climatológicas locais, a fim de se conhecer a influência do clima no crescimento das árvores. Foram utilizadas séries de precipitação, temperatura e da evapotranspiração. O estudo aponta que as variáveis climatológ...

In this work, the Sun–Earth–climate relationship is studied using tree growth rings of Araucaria angustifolia (Bertol.) O. Kuntze collected in the city of Passo Fundo, located in the state of Rio Grande do Sul (RS), Brazil. These samples were previously studied by Rigozo et al. (2008); however, their main interest was to search for the solar period...

This work aims to demonstrate the analytical solution of the Grad-Shafranov (GS) equation or generalized Ampere’s law, which is important in the studies of self-consistent 2.5-D solution for current sheet structures. A detailed mathematical development is presented to obtain the generating function as shown by Walker (RSPSA 91, 410, 1915). Therefor...

The interaction between a fast-speed and a low-speed stream causes large-amplitude Alfvénic fluctuations; consequently, the intermittency and the brief intervals of southward magnetic field associated with Alfvén waves may cause high levels of AE activity, the so-called high-intensity, long-duration, continuous AE activity (HILDCAA). In this articl...

This article proposes some traditional and newly developed methods to evaluate the properties of the magnetic cloud (MC) observed on 19 – 22 March 2001. We used physical and mathematical approaches to analyze the time series of solar wind plasma and interplanetary magnetic field data. Two methods that are commonly used to derive the MC properties,...

In this paper, we investigated the interplanetary conditions during 124 less strict high-intensity, long-duration, continuous AE activity (HILDCAA∗) events between the years of 1998 and 2007. The HILDCAA∗ events were chosen by following three “traditional” criteria of high-intensity, long-duration, continuous AE activity (HILDCAA) events which are...

Spatio-temporal entropy (STE) analysis is used as an alternative mathematical tool to identify possible magnetic cloud (MC) candidates. We analyze Interplanetary Magnetic Field (IMF) data using a time interval of only 10 days. We select a convenient data interval of 2500 records moving forward by 200 record steps until the end of the time series. F...

We investigate the interplanetary conditions during 135 less strict high-intensity, long-duration, continuous AE activity (HILDCAA*) events during the years of 1998--2007. The HILDCAA* events were chosen by following strictly three of the "traditional" criteria which describe the high-intensity, long-duration, continuous AE activity (HILDCAA). Howe...

We discuss the relationship between the Coulomb gauge, the existence of an invariant axis, and the dimensionality (2-D or 212-D) of the magnetic field in a mathematical-physical formalism that leads us to the Grad-Shafranov (GS) equation. In the literature, we found that a 2-D magnetic structure is used as a prerequisite to derive the GS equation f...

Samples of Araucaria angustifolia were collected at Fazenda Rio Grande, Paraná, Brazil (25º39’S 49 18’O) in January 2011. The 32 samples from 8 trees were subjected to treatments following dendrochronological techniques. The cores were measured and dated using optical and computational methodology, and then standardized to obtain a growth-ring time...

The Grad-Shafranov equation is a Poisson’s equation, i.e., a partial differential equation of elliptic type. The problem is depending on the initial condition and can be treated as a Cauchy problem. Although it is ill-posed or ill-conditioned, it can be integrated numerically. In the integration of the GS equation, singularities with large values o...

This study used a 300 year-old mean chronology (1700-2010) that was determined by means of tree-growth rings from General Carneiro, Southern Brazil, in order to search signs of solar cycle and El Niño South Oscilation (ENSO). The most important aspect of solar variability is the 11-year cycle (Schawbe Cycle) which is characterized by reversal of th...

Evidence of the solar activity modulation of the Earth's climate has been observed on several parameters, from decadal to millennial time scales. Several proxies have been used to reconstruct the paleoclimate as well as the solar activity. The paleoclimate reconstructions are based on direct and/or indirect effects of global and regional climate co...

This work investigates the behavior of the sunspot number and Southern Oscillation Index (SOI) signal recorded in the tree ring time series for three different locations in Brazil: Humaitá in Amazônia State, Porto Ferreira in São Paulo State, and Passo Fundo in Rio Grande do Sul State, using wavelet and cross-wavelet analysis techniques. The wavele...

This paper presents a study on the relationship about tree-rings growth of samples of the Araucaria angustifolia species and climatic events which occurred during life of these trees. In this study, we used temporal series of tree-rings from Concórdia-SC and time series of the Southern Oscillation Index (SOI), both series covering the period from 1...

In this work we focus on the year of 2003 when the AE index was extremely high (AE=341nT, with peak intensity more than 2200nT), this value is almost 100 nT higher when compared with others years of the cycle 23. Interplanetary magnetic field (IMF) and plasma data are compared with geomagnetic AE and Dst indices to determine the causes of exception...

The Brazilian Solar Spectroscope (BSS), in operation at INPE, Brazil, have recorded a group of radio spikes observed on June 24, 1999 (16:53 - 16: 56 UT), in the decimeter frequency range of 1000-2500 MHz, with high temporal resolution of 100 ms and spectral resolution of 10 MHz. This event presents distinct clusters of spikes with intermittent beh...

In this work, we analyze the long term variability of rainfall and temperature (1912-2008) of Santa Maria (29°S, 53°W) and its possible connection with natural influences such as solar activity and ENSO. Temperature and rainfall present similar frequencies as revealed by spectral analyses. This analysis shows a large number of short periods between...

This study of Sun–Earth relationships is based on tree growth rings analysis of araucarias (Araucaria angustifolia) collected at Severiano de Almeida (RS) Brazil. A chronology of 359 years was obtained, and the classical method of spectral analysis by iterative regression and wavelet method was applied to find periodicities and trends contained in...

There is one suggestion that solar activity and climate are linked by cloud formation. Clouds are formed by water vapor condensing onto small particles called aerosols. Cosmic rays can interact with the atmosphere through various chemical reactions that can create aerosols and hence help the formation of clouds. Cosmic rays consist mainly of proton...

This work presents a study of the relations between solar and climate variations during the last millennia by spectral and multi-resolution analysis for oxygen-18 and tree ring width time series. The spectral and wavelet analysis of tree ring data shows that main solar cycle periodicities are present in our time series at the 0.95 confidence level....

A tree-ring thickness time series from Passo Fundo (Southern Brazil) for the interval 1741–2004 was studied by spectral, wavelet and cross-wavelet analyses in order to identify the non-stationary characteristics in tree-ring and sunspot number data. Periods corresponding to the solar cycles of 11, 22, and 80 yr were found. The 11 yr solar cycle is...

In this work we apply the wavelet transform to the Pelotas (southern Brazil) total annual rainfall series (1894–1995). Classical, wavelet and cross-wavelet analyses were performed in the El Niño Southern Oscillation (ENSO), Quasi-Biennial Oscillation (QBO), sunspot number (Rz) and Pelotas rainfall time series. Classical spectral analysis for Pelota...

This paper is in Portuguese. Tree ring thickness time series from Passo Fundo -RS (Southern Brazil) for the interval 1741-2004 was studied by spectral, wavelet and cross-wavelet analysis in order to identify non stationary characteristics in tree rings and sunspot numbers. Solar cycles of 11,22, 54, 80 and 208 yr were evidenced. The 11-yr solar cyc...

We have investigated the solar activity signal in tree ring data from two locations in Chile. The tree ring time series extended over a period of ∼400yr. Spectral and wavelet analysis techniques were employed. We have found evidence for the presence of the solar activity Schwabe (∼11yr), Hale (∼22yr), fourth-harmonic of the 208-yr Suess cycle (∼52y...

Evidences of the solar activity modulation of the Earth's climate have been observed on different time scales. The main solar activity mechanisms to control climate proposed to explain these observations are: (1) the variability of the total solar irradiance causing a change in the total energy input to the earth's atmosphere and consequent warming...

We present a new interactive method for tree-ring width determination. It uses a high-resolution scanner and a microcomputer in which a program to study scanned tree-ring images was developed within Interactive Data Language (IDL 5.0) environment. The main advantage of this method is to perform an interactive tree-ring image analysis without needin...

Tree growth rings represent an important natural record of past climate variations and of solar activity effects registered on them. We performed in this study a wavelet analysis of tree ring samples from Chile and Brazil. We obtained an average chronology of about 158 yr from these trees. The 11-yr solar cycle was present during the 1930 1954 inte...

The multiple-taper spectral analysis was applied to aa, Ap and Rz annual and monthly average series (1868–2001). The significant periods at 95% confidence level for annual averages are 11.1 and 10.2 years for Rz and 11.1, 5.3, 4.3, 2.7 and 2.1 years for aa. For monthly averages, the significant periods were 133 (11.1 years) and 17.7 months for Rz a...

In this work a study is performed on the correlation between fast forward interplanetary shock parameters at 1 Astronomical Unit and sudden impulse (SI) amplitudes in the H-component of the geomagnetic field, for periods of solar activity maximum (year 2000) and minimum (year 1995-1996). Solar wind temperature, density and speed, and total magnetic...

Solar activity, volcanic aerosol, El Niño-Southern Oscillation and global temperature anomalies effects on Southern Brazil tree growth rings are presented through multiple linear analysis. Linear correlations were made on annual, 10 year running averages and band pass filter. For annual averages, the correlation coefficients were low, and the 10 ye...

Spectral and wavelet analysis were performed on a tree ring width time series obtained from a 2500 yr old cypress tree (Fitzroya cupressoides) from Costa del Osorno, Chile. The periods for analysis were selected at 95% confidence level. Both periodicities characteristic of solar activity and climatic variations were found in this tree ring width se...

The objective of this paper is to compare the spectral features of the recently derived Group Sunspot Numbers (R G) and the traditional Wolf Sunspot Numbers (R Z) for the 1700–1995 period. In order to study the spectral features of both time series, two methods were used, including: (a) the multitaper analysis and (b) the wavelet analysis. Well-kno...

A long-term correlation study between solar and geomagnetic activity is reported in this work using annual averages of the aa index and of the sunspot number Rz in the period of 1868–2000. Dst and AE geomagnetic indices and solar wind speed data are used for more recent periods. It is shown that the geomagnetic and solar activity correlation has de...

In this work we analyze the climatic effects of the solar activity (radio flux at 10.7cm, F10.7cm) and factors (Southern Oscillation Index - El Niño, SOI; measure of the Stratospheric Aerosols Optic Depth, SAOD; temperature of station of Porto Alegre, precipitation) in tree-rings growth through spectral analysis, multiple regression and cross corre...

This work presents a study of the relations between solar and climate variations during the last four centuries by spectral analysis of tree ring index and sunspot number time series. Trees used for this study were Pilgerodendron cupressoides from Glaciar Pio XI, in Chile. The spectral analysis of tree ring index shows that 11, 22 and 80 year perio...

The influence of El Niño/Southern Oscillation (ENSO) phenomenon on precipitation in Chile is analyzed using precipitation data recorded in various Chilean cities at latitudes varying from 29°S to 53°S, for time intervals between 56 and 128 years. Spectral analysis was performed using Morlet wavelet transform. Among the twelve cities object of this...

The sunspot number is the longest solar activity index available with observations since 1611. It is a measure of the general state of solar magnetic activity. In this work we present a desciption of sunspot physical caracteristics, the definition of the sunspot number, a spectral analysis and a reconstruction for the last 1000 years of the sunspot...

O número de manchas solares é o índice mais antigo da atividade solar, com observações de manchas solares estendendo-se desde 1611. Ele serve como uma medida da atividade magnética geral do Sol. Neste trabalho apresentamos uma descrição das características físicas das manchas solares, a definição do número de manchas solares, uma análise espectral...

The sunspot number is the longest solar activity index available with observations since 1611. It is a measure of the general state of solar magnetic activity. In this work we present a desciption of sunspot physical caracteristics, the definition of the sunspot number, a spectral analysis and a reconstruction for the last 1000 years of the sunspot...

Spectral analysis using the multiple taper method was performed on a tree ring width time series obtained from a cypress tree (Fitzroya cupressoides) of 2500 years, at Costa del Osorno, Chile. The periods for analysis were selected at 95% confidence level. Both periodicities characteristic of solar activity and climatic variation were found in this...

Interplanetary shock parameters are analyzed for solar maximum (year 2000) and solar minimum (years 1995-1996) activity. Fast forward shocks are the most usual type of shock observed in the interplanetary medium near Earth's orbit, and they are 88% of the identified shocks in 2000 and 60% in 1995-1996. Average plasma and magnetic field parameters f...

In this work we present a methodology to estimate the geomagnetic symmetric index (Sym) based on the wavelet analysis of the time series of the H component of the geomagnetic field measured at mid-latitude stations localized at Kakioka (KAK), Honolulu (HON), Hermanus (HER) and San Juan (SJG). A case study of the intense geomagnetic storm of 17–22 F...

1 ture of the magnetic clouds. It is usually observed high-speed streams interacting in the rear part a ejecta. It was shown that this interaction leads to the compression of the magnetic field and, in consequence, the increase of the geoeffectivess of the ejecta it- self. These high-speed streams could emanate from coronal holes or they could be t...

It is known for long time that during the main phase of magnetic storms it is observed a partial ring current that develops in the dusk-midnight sector. In this paper it was proposed a original methodology based on wavelet analysis to separate time and space variations observed in mid-latitude geomagnetic records and it was studied the interplaneta...

The occurrence of substorms with long duration and high intensity in the auroral region has been analyzed from January to December 1998. These events were called HILDCAAs and are characterized by increases in the auroral eletrojet verified by AE index, with small variations in Dst index, that correspond to the ring current intensification, in the s...

In this work we present a methodology to estimate the geomagnetic symmetric index (SYM) based on the wavelet analysis of the time series of the H component of the geomagnetic field measured at medium latitude stations local-ized at Kakioka (KAK), Honolulu (HON), Hermanus (HER) and San Juan (SJG). A case study of the intense geo-magnetic storm of Fe...

The Multiple-Taper spectral analysis was applied to both Aa and Rz annual and monthly average series (1868-2000). The significant periods at 95% confidence level for annual averages were 11.1 and 10.2 years for Rz and 11.1, 5.3, 4.3, 2.7 and 2.1 years for Aa. For monthly averages, the significant periods were 133 (11 years), 18.5 and 17. 7 months f...

Interplanetary Magnetic Field (IMF) fluctuations with short period and small intensity have been correlated to HILDCAA occurrence. During these events, small variations in Dst index and large changes in auroral electrojet, measured by AE index, may be observed. The November 28-30, 1998 HILDCAA event was selected in order to analyze the dominant fre...

Presentamos un nuevo método interactivo para la determinación de la anchura de los anillos de los árboles. Se usa un escaner de la alta resolución y un microordenador en los que se trabaja con un programa para estudiar imágenes de anillos de árboles que se desarrolló dentro del ambiente Interactive Data Language (IDL 5.0). La ventaja principal de e...

We have compared characteristics of 85 halo CMEs observed on the sun by the Large Angle and Spectroscopic Coronagraph on SOHO with their corresponding counterparts observed near earth by the magnetic field and plasma instruments on board of ACE, WIND and SOHO satellites, in the period from January 1997 to April 2001. First, we focussed on the compa...

The geomagnetic activity is modulated by solar activity level, characterized by sunspot number Rz. The variations on the SunSs atmosphere are transmitted to the EarthSs magnetosphere through the solar wind. During a solar cycle, different structures contribute to the geomagnetic activity level, for example, fast streams emitted from low latitude co...

The energy received from the Sun is one of the natural driving forces of the Earths atmosphere and since this energy varies with time, it may affect climate. Consequently, many studies have purported to show correlations between solar activity and various meteorological parameters. Rainfall is the most common meteorological parameters used to defin...