[pt] A origem da vida ainda é uma questão aberta na ciência. Dentre as possíveis respostas, a panspermia é uma alternativa amplamente discutida. Ao investigar esta possibilidade, o desenvolvimento de modelos que descrevam o comportamento de moléculas interagindo com raios cósmicos são de extrema importância. Para esta finalidade, filmes finos de diferentes espessuras de bases nitrogenadas - adenina, citosina, guanina e timina - foram depositados sobre pastilhas de ZnSe para serem irradiados por elétrons de 1,0 e 0,50 keV. A adenina foi irradiada sob diferentes temperaturas. Após cada irradiação parcial, a espectroscopia óptica na região do infravermelho (FTIR) foi usada para monitorar as modificações nas características espectrais. Observou-se que a seção de choque de destruição das bases nitrogenadas irradiadas é aproximadamente 10 elevado a -16 cm quadrados e, para a adenina, este valor aumenta para temperaturas baixas. Com base nos dados obtidos de glicina, o tempo de meia vida de adenina pura processada por vento solar a 1 UA estimado é de cerca de 40 dias. A seção de choque varia muito pouco quando as espessuras dos filmes são aumentadas de 10 para 30 nm, e os valores encontrados para as quatro bases seguem a ordem: citosina, adenina, guanina e timina, respectivamente, da menos para a mais radioresistente. Para melhor compreender o significado dos resultados experimentais, previsões foram obtidas com o algoritmo CASINO-estendido e apresentam bom acordo se radiólise e sputtering são considerados. / [en] The origin of life is still an open question in science. Among the possible answers, panspermia is a widely discussed alternative. To investigate this possibility, the development of models that describe the behavior of molecules interacting with cosmic rays is extremely important. For this purpose, thin films of different thicknesses of nitrogenous bases - adenine, cytosine, guanine, and thymine - were deposited on ZnSe disks to be irradiated by 1.0 and 0.50 keV electrons. Adenine was irradiated under different temperatures. After each partial irradiation, optical spectroscopy in the infrared region (FTIR) was used to monitor changes in spectral characteristics. It is observed that the destruction cross sections of irradiated nitrogenous bases are approximately 10 raised to -16 square cm and, for adenine, this value increases at low temperatures. In comparition to glycine data, the estimated half-life of pure adenine when processed at 1 au by the solar wind is about 100 days. The cross section varies very little when the film thicknesses are increased from 10 to 30 nm, and the bases follow the order: cytosine, adenine, guanine and thymine, respectively, from the least to the most radioresistant. To better analyze the experimental data, they are compared with predictions obtained with the CASINOextended algorithm. They are in good agreement if radiolysis and sputtering are considered.

Since Venus is an unmagnetized planet, it doesn’t interact with the solar wind in the same way as planets with an intrinsic magnetic field do. Due to its conductive ionosphere, however, it still possesses an induced magnetosphere. Venus’s magnetosphere contains different boundaries, identified by changes in the plasma or magnetic field characteristics. The boundaries we studied in this project are the bow shock and the Ion Composition Boundary (ICB). Previous studies identified the boundaries’ locations and compared them with plasma measurements outside of the magnetosphere, finding how the boundaries react to varying solar wind upstream conditions. What has been more rarely done, instead, is to find the analytical dependency of the bow shock and ICB on the upstream conditions. This was the purpose of this project. Developing this comprehensive analytical model allows us to determine the location of the boundaries, once the upstream conditions are defined. We used a database of boundary crossings and upstream conditions measurements deriving from the Venus EXpress (VEX). The procedure we followed was first to divide the boundaries crossings into bins, analyzing one upstream condition at a time. Then, we fitted the crossings using analytical equations depending on geometrical parameters. For the bow shock we used a conic section with semi-latus rectum L and eccentricity ε as geometrical parameters, for the dayside ICB we used a circumference with the radius R as geometrical parameter. We fitted these geometrical parameters with the upstream conditions in each bin and found the final model. The final equation for the bow shock depends on the Interplanetary Magnetic Field (IMF) magnitude, the solar wind mass flux, and the angle between the IMF direction and the local shock normal. For the ICB the final equation depends on the solar wind energy flux and the solar Extreme UltraViolet (EUV) flux. Given these solar wind and IMF properties, the geometrical parameters of the boundaries are uniquely identified. Then, we were able to determine the boundaries’ locations and shapes with higher accuracy than the general fitting models that don’t consider upstream conditions. For the bow shock we improved the accuracy by 17%, for the ICB by 8%. / Eftersom Venus är en omagnetisk planet växelverkar den inte med solvinden på samma sätt som planeter med ett inneboende magnetfält. På grund av sin ledande jonosfär har den dock fortfarande en inducerad magnetosfär. Venus magnetosfär innehåller olika gränser, identifierade av förändringar i plasma- eller magnetfältets egenskaper. Gränserna vi studerade i det här projektet är bogshocken och Ion Composition Boundary (ICB). Tidigare studier identifierade gränsernas lägen och jämförde dem med plasmamätningar utanför magnetosfären, och hittade hur gränserna ändras med varierande solvind uppströms. Vad som har gjorts mer sällan är att hitta det analytiska beroendet av bogchocken och ICB på uppströmsförhållandena. Det var syftet med det här projektet. Genom att utveckla de här analytiska modellerna kan vi bestämma placering för gränserna när uppströmsförhållandena har definierats. Vi använde en databas med gränsövergångar och mätningar av uppströmsförhållanden härrörande från Venus EXpress (VEX). Proceduren vi följde var först att dela upp gränsövergångarna i dataintervall och analysera ett uppströmsläge i taget. Sedan anpassade korsningarna med hjälp av analytiska ekvationer beroende på geometriska parametrar. För bogshocken använde vi en konisk sektion med semi-latus rektum L och excentricitet ε som geometriska parametrar, för dagsida ICB använde vi en omkrets med radien R som geometrisk parameter. Vi anpassade de här geometriska parametrarna för olika uppströmsförhållanden och tog fram en modell. Den slutliga ekvationen för bogshocken beror på det interplanetära magnetfältets (IMF) magnitud, solvindens rörelsemängd och vinkeln mellan IMF och den lokala shocknormalen. För ICB beror den slutliga ekvationen på solvindenergiflödet och extrem ultraviolett (EUV) flöde. Med avseende på de här solvinds- och IMF-egenskaperna är de geometriska parametrarna för gränserna identifierade. Sedan kunde vi bestämma gränsernas placeringar och former med högre noggrannhet än de allmänna modellerna som inte tar hänsyn till uppströmsförhållanden. För bogchocken förbättrade vi noggrannheten med 17% och för ICB med 8%.

No description available.

Using multiple theoretical methods, comprehensive calculations are performed to create a new and more comprehensive data set for elastic scattering and related transport cross sections for collisions of (H$^+$ + H), (H + H) and (He$^{2+}$ + H) in the center-of-mass energy frame. In proton-atomic hydrogen collisions, we have significantly updated and extended previous work of elastic scattering, charge transfer and related transport integral and differential cross sections in the center-of-mass energy range $10^{-4} - 10^4$ eV where the multi-channel molecular orbital approach (MO3) is used. For atomic hydrogen-hydrogen collisions, similar updates have been made of elastic scattering and spin exchange differential and integral cross sections, also for the H + H collision the ionization and negative ion formation cross sections are provided in energy range (1-20 KeV) by use of the 'hidden crossing' theoretical framework. For collisions of alpha particles with atomic hydrogen we have computed the elastic scattering cross section in the center-of-mass energy range $10^{-4} - 10^8$ eV. In this case, at the lowest energies where elastic scattering greatly dominates other reaction channels, a single-channel quasi-molecular-orbital approach (MO1) is used. With the opening of inelastic channels at higher energies the multi-channel atomic-orbital, close-coupling method is applied, and at the highest energies considered perturbation theory (the Born approximation) is used. The results are compared with other data available in literature.

The solar wind, magnetosphere and ionosphere are coupled by magnetohydrodynamic waves, and this gives rise to new and often unexpected behaviours that cannot be produced by a single, isolated part of the system. This thesis examines two broad instances of coupling: field-line resonance (FLR) which couples fast and Alfvén waves, and magnetosphere-ionosphere (MI-) coupling via Alfvén waves. The first part of this thesis investigates field-line resonance for equilibria that vary in two dimensions perpendicular to the background magnetic field. This research confirms that our intuitive understanding of FLR from 1D is a good guide to events in 2D, and places 2D FLR onto a firm mathematical basis by systematic solution of the governing equations. It also reveals the new concept of ‘imprinting’ of spatial forms: spatial variations of the resonant Alfvén wave correlate strongly with the spatial form of the fast wave that drives the resonance. MI-coupling gives rise to ionosphere-magnetosphere (IM-) waves, and we have made a detailed analysis of these waves for a 1D sheet E-region. IM-waves are characterised by two quantities: a speed v_{IM} and an angular frequency ω_{IM} , for which we have obtained analytic expressions. For an ideal magnetosphere, IM-waves are advective and move in the direction of the electric field with speed v_{IM}. The advection speed is a non-linear expression that decreases with height-integrated E-region plasma-density, hence, wavepackets steepen on their trailing edge, rapidly accessing small length-scales through wavebreaking. Inclusion of electron inertial effects in the magnetosphere introduces dispersion to IM-waves. In the strongly inertial limit (wavelength λ << λ_{e} , where λ_{e} is the electron inertial length at the base of the magnetosphere), the group velocity of linear waves goes to zero, and the waves oscillate at ω_{IM} which is an upper limit on the angular frequency of IM-waves for any wavelength. Estimates of v_{IM} show that this speed can be a significant fraction (perhaps half) of the E_{⊥} × B_{0} drift in the E-region, producing speeds of up to several hundred metres per second. The upper limit on angular frequency, ωIM , is estimated to give periods from a few hundredths of a second to several minutes. IM-waves are damped by recombination and background ionisation, giving an e-folding decay time that can vary from tens of seconds to tens of minutes. We have also investigated the dynamics and steady-states that occur when the magnetosphere-ionosphere system is driven by large-scale Alfvénic field-aligned currents. Steady-states are dominated by two approximate solutions: an ‘upper’ solution that is valid in places where the E-region is a near perfect conductor, and a ‘lower’ solution that is valid where E-region depletion makes recombination negligible. These analytic solutions are extremely useful tools and the global steady-state can be constructed by matching these solutions across suitable boundary-layers. Furthermore, the upper solution reveals that E-region density cavities form and widen (with associated broadening of the magnetospheric downward current channel) if the downward current density exceeds the maximum current density that can be supplied by background E-region ionisation. We also supply expressions for the minimum E-region plasma-density and shortest length-scale in the steady-state. IM-waves and steady-states are extremely powerful tools for interpreting MI-dynamics. When an E-region density cavity widens through coupling to an ideal, single-fluid MHD magnetosphere, it does so by forming a discontinuity that steps between the upper and lower steady-states. This discontinuity acts as part of an ideal IM-wave and moves in the direction of the electric field at a speed U = \sqrt{v_{IM} {+} v_{IM} {-}}, which is the geometric mean of v_{IM} evaluated immediately to the left and right of the discontinuity. This widening speed is typically several hundreds of metres per second. If electron inertial effects are included in the magnetosphere, then the discontinuity is smoothed, and a series of undershoots and overshoots develops behind it. These undershoots and overshoots evolve as inertial IM-waves. Initially they are weakly inertial, with a wavelength of about λ_{e}, however, strong gradients of ω_{IM} cause IM-waves to phase-mix, making their wavelength inversely proportional to time. Therefore, the waves rapidly become strongly inertial and oscillate at ω_{IM}. The inertial IM-waves drive upgoing Alfvén waves in the magnetosphere, which populate a region over the downward current channel, close to its edge. In this manner, the E-region depletion mechanism, that we have detailed, creates small-scale Alfvén waves in large-scale current systems, with properties determined by MI-coupling.

The coronal mass ejections (CMEs) are phenomena that evidence the complex solar activity. During the CME evolution in the solar wind (SW) the shock and sheath (Sh) are established. With these, the transfer of energy and shock thermalization have origin through several processes like instabilities and particle acceleration. Here, we present two studies related to CMEs. In the first study, we analyze the existence of the KelvinHelmholtz instability (KHI) at the interfaces CMESh and ShSW. For this purpose, we assumed two CMEs that propagate independently in the slow and fast SW. We model velocities, densities and magnetic field strengths of sheaths, and SW in the CMEs flanks, in order to solve the Chandrasekhar condition for the magnetic KHI existence. Our results reveal that KHI formation is more probably in the CME that propagate in the slow SW than in CME propagating in the fast SW. It is due to large shear flow between the CME and the slow SW. Besides we find that the interface ShSW is more susceptible to the instability. In the second study, we examine the distributions of particle acceleration and turbulence regions around CME-driven shocks with wave-like features. We consider these corrugated shock as the result of disturbances from the bimodal SW, CME deflection, irregular CME expansion, and the ubiquitous fluctuations in the solar corona. We model smooth CME-driven shocks using polar Gaussian profiles. With the addition of wave-like functions, we obtain the corrugated shocks. For both shock types are calculated the shock normal angles between the shock normal and the radial upstream coronal magnetic field in order to classify the quasi-parallel and quasi-perpendicular regions linked to the particle acceleration and turbulence regions, respectively. Our calculations show the predisposition of the shock to the particle acceleration and indicate that the irregular CME expansion is the relevant factor in the particle acceleration process. We consider that these wave-like features in shocks may be essential in the study of current problems as injection particle, instabilities, downstream-jets, and shock thermalization. / As ejeções de massa coronal (do inglês coronal mass ejections, CMEs) são consideradas traçadores da atividade solar. Durante a evolução das CMEs no vento solar (do inglês solar wind, SW), o choque e o envoltório (do inglês sheath, Sh) são estabelecidos. Nesta fase, a transferência da energia e a termalização do choque podem ter origem através de vários processos, entre eles instabilidades e aceleração de partculas. Aqui nós apresentamos dois estudos relacionados às CMEs. No primeiro estudo, analisamos a existência da instabilidade KelvinHelmholtz (KHI) nas interfaces CMESh e ShSW. Para isto, supomos duas CMEs que se propagam independentemente no SW lento e rápido. Modelamos as velocidades, densidades e a intensidade do campo magnético dos envoltórios e SW nos flancos das CMEs, a fim de resolver a condição de Chandrasekhar para a existência da KHI magnética. Nossos resultados revelam que a formação da KHI pode ser mais provável na CME que se propaga no SW lento do que na CME que se propaga no SW rápido. Isto é devido a um maior cisalhamento entre a CME e o SW lento. Além disso, encontramos que a interface ShSW é ser mais suscetvel à instabilidade. No segundo estudo, examinamos as distribuições das regiões de aceleração de partculas e turbulência em choques ondulados com caractersticas semelhantes a ondas. Assumimos choques ondulados como resultado de perturbações do SW bimodal, deflexão da CME, expansão irregular da CME, e flutuações onipresentes na coroa solar. Construmos choques sem ondulações usando perfis Gaussianos. Com adição de funções semelhantes a ondas, obtemos os choques ondulados. Para ambos tipos de choques, calculamos os ângulos entre o vector normal ao choque e o campo magnético coronal radial, assim classificamos as regiões como quase-paralelas e quase-perpendiculares que são ligadas às regiões de aceleração de partculas e turbulência, respectivamente. Nossos cálculos mostram a predisposição do choque para o fenômeno de acceleração de partculas, e indicam que a expansão irregular da CME é o fator de maior relevância neste processo. Consideramos que assumir ondulações nos choques pode ser essencial nos estudos de problemas atuais como injeção de partculas, instabilidades, jatos e termalização dos choques.

The coronal mass ejections (CMEs) are phenomena that evidence the complex solar activity. During the CME evolution in the solar wind (SW) the shock and sheath (Sh) are established. With these, the transfer of energy and shock thermalization have origin through several processes like instabilities and particle acceleration. Here, we present two studies related to CMEs. In the first study, we analyze the existence of the KelvinHelmholtz instability (KHI) at the interfaces CMESh and ShSW. For this purpose, we assumed two CMEs that propagate independently in the slow and fast SW. We model velocities, densities and magnetic field strengths of sheaths, and SW in the CMEs flanks, in order to solve the Chandrasekhar condition for the magnetic KHI existence. Our results reveal that KHI formation is more probably in the CME that propagate in the slow SW than in CME propagating in the fast SW. It is due to large shear flow between the CME and the slow SW. Besides we find that the interface ShSW is more susceptible to the instability. In the second study, we examine the distributions of particle acceleration and turbulence regions around CME-driven shocks with wave-like features. We consider these corrugated shock as the result of disturbances from the bimodal SW, CME deflection, irregular CME expansion, and the ubiquitous fluctuations in the solar corona. We model smooth CME-driven shocks using polar Gaussian profiles. With the addition of wave-like functions, we obtain the corrugated shocks. For both shock types are calculated the shock normal angles between the shock normal and the radial upstream coronal magnetic field in order to classify the quasi-parallel and quasi-perpendicular regions linked to the particle acceleration and turbulence regions, respectively. Our calculations show the predisposition of the shock to the particle acceleration and indicate that the irregular CME expansion is the relevant factor in the particle acceleration process. We consider that these wave-like features in shocks may be essential in the study of current problems as injection particle, instabilities, downstream-jets, and shock thermalization. / As ejeções de massa coronal (do inglês coronal mass ejections, CMEs) são consideradas traçadores da atividade solar. Durante a evolução das CMEs no vento solar (do inglês solar wind, SW), o choque e o envoltório (do inglês sheath, Sh) são estabelecidos. Nesta fase, a transferência da energia e a termalização do choque podem ter origem através de vários processos, entre eles instabilidades e aceleração de partculas. Aqui nós apresentamos dois estudos relacionados às CMEs. No primeiro estudo, analisamos a existência da instabilidade KelvinHelmholtz (KHI) nas interfaces CMESh e ShSW. Para isto, supomos duas CMEs que se propagam independentemente no SW lento e rápido. Modelamos as velocidades, densidades e a intensidade do campo magnético dos envoltórios e SW nos flancos das CMEs, a fim de resolver a condição de Chandrasekhar para a existência da KHI magnética. Nossos resultados revelam que a formação da KHI pode ser mais provável na CME que se propaga no SW lento do que na CME que se propaga no SW rápido. Isto é devido a um maior cisalhamento entre a CME e o SW lento. Além disso, encontramos que a interface ShSW é ser mais suscetvel à instabilidade. No segundo estudo, examinamos as distribuições das regiões de aceleração de partculas e turbulência em choques ondulados com caractersticas semelhantes a ondas. Assumimos choques ondulados como resultado de perturbações do SW bimodal, deflexão da CME, expansão irregular da CME, e flutuações onipresentes na coroa solar. Construmos choques sem ondulações usando perfis Gaussianos. Com adição de funções semelhantes a ondas, obtemos os choques ondulados. Para ambos tipos de choques, calculamos os ângulos entre o vector normal ao choque e o campo magnético coronal radial, assim classificamos as regiões como quase-paralelas e quase-perpendiculares que são ligadas às regiões de aceleração de partculas e turbulência, respectivamente. Nossos cálculos mostram a predisposição do choque para o fenômeno de acceleração de partculas, e indicam que a expansão irregular da CME é o fator de maior relevância neste processo. Consideramos que assumir ondulações nos choques pode ser essencial nos estudos de problemas atuais como injeção de partculas, instabilidades, jatos e termalização dos choques.

Ideal magnetohydrodynamics (MHD) simulations are known to have problems in satisfying the solenoidal constraint (i.e. the divergence of magnetic field should be equal to zero, $ ablacdotvec{B} = 0$). The simulations become unstable unless specific measures have been taken. In this thesis, a solenoidal constraint satisfying technique that allows discrete satisfaction of the solenoidal constraint up to the machine accuracy is presented and validated with a variety of test cases. Due to its inspiration from Chorin's artificial compressibility method developed for incompressible CFD applications, the technique was named as extit{artificial compressibility analogy (ACA)} approach. It is demonstrated that ACA is a purely hyperbolic, stable and consistent technique, which is moreover easy to implement. Unlike some other techniques, it does not pose any problems of the sort that $ ablacdotvec{B}$ errors accumulate in the vicinity of the stagnant regions of flow. With these crucial properties, ACA is thought to be a remedy to the drawbacks of the most commonly used solenoidal constraint satisfying techniques in the literature namely: Incorrect shock capturing and poor performance of the convective stabilization mechanism in regions of stagnant flow for Powell's source term method; exceedingly complex implementation for constrained transport technique due to the staggered grid representation; computationally expensive nature due to the necessity of a Poisson solver combined with hyperbolic/elliptic numerical methods for classical projection schemes. In the first chapter of the thesis, general background knowledge is given about plasmas, MHD and its history, a certain class of upwind finite volume methods, namely Riemann solvers, and their applications in MHD, the definition, constituents, formation mechanisms and effects of space weather and some of the space missions that are and will be performed in its prediction. Secondly, detailed analysis of the compressible ideal MHD equations is given in the form of the derivation of the equations, their dimensionless numbers which will be of use to specify the flows in the following chapters, and finally, the presentation of the MHD waves and discontinuities, which indicates the complexity of the system of ideal MHD equations and therefore their further numerical analysis. The next discussion is about the main subject of the thesis, namely the solenoidal constraint satisfying techniques. First of all, the definition and significance of the solenoidal constraint is given. Afterwards, the most common solenoidal constraint satisfying techniques in the literature are reviewed along with their abovementioned drawbacks. Moreover, particular emphasis is given to the Powell's source term approach which was also implemented in the upwind finite volume MHD solver developed. In addition, the hyperbolic divergence cleaning technique is presented in detail together with the resemblance and differences between it and ACA. Some other solenoidal constraint satisfying techniques are briefly mentioned at this stage. After these, ACA is presented in the following way: The point of inspiration, which is the analogy made with Chorin's artificial compressibility method developed for incompressible CFD, the introduction of the modified system of ideal MHD equations due to ACA, the derivation of the wave equation governing the propagation of $ ablacdotvec{B}$ errors and the analytical consistency proof. Having finished the core discussion of the thesis, the solver developed and its constituents are given in the fourth chapter. Furthermore, a brief overview of the platform into which this solver was implemented, namely COOLFluiD, is also given at this point. Afterwards, a thorough numerical verification of the ACA approach has been made on an increasingly complex suite of test cases. The results obtained with ACA and Powell's source term implementations are given in order to numerically analyse and verify ACA and compare the two methods and validate them with the results from literature. The sixth chapter is devoted to further validation of ACA performed with a variety of more advanced space weather-related simulations. In this chapter, also the $vec{B}_{ extrm{0}} + vec{B}_{ extrm{1}}$ splitting technique used to treat planetary magnetosphere is presented along with its application to ACA and Powell's source term approaches. This technique is utilized in obtaining the solar wind/Earth's magnetosphere interaction results and is based on suppressing the direct inclusion of the Earth's magnetic field, which is a dipole field, in the solution variables. In this way, problems are avoided with the energy equation that could arise from the drastic change of the ratio of the dipole field and the variable field computed by the solver (i.e. $frac{lvertvec{B}_{ extrm{0}}lvert}{lvertvec{B}_{ extrm{1}}lvert}$) in the computational domain. Finally, conclusions and future perspectives related to the material presented in the thesis are put forward.

No description available.

This thesis analyzes the monthly data from historical series of the heat stroke cycles, solar radiation and average wind speeds in the 1961 and 2008 period to identify long-term inaccuracies in the location of both wind and solar sources. The state of Rio Grande do Sul-Brazil, was chosen as a case study, to estimate the behavioral trend of these variables and compare them with the measured data, testing the homogeneity of information. Therefore, it aims at improving the long-term prognosis in locating projects of solar power generation plants. The analysis of these climatic variables was carried out using ARIMA models (autoregressive integrated moving average models) as well as the Box & Jenkins methodology and seasonality studies with the X11 ARIMA models with 5% statistical significance. In this study, the period between 1961 and 2011 indicated that heat stroke rates were not enough to overcome the values recorded in the 1960s and 1970s, when the percentages were in most months 1% below the historical average. The observed heat stroke data suggest decreasing trends in the 1980s and 1990s, due to the presence of the phenomenon called "global dimming", which contributed to lower levels of solar radiation.!A possible structural break has been found in the wind series from August 2001 through the CUSUMQ test (cumulative sum of squares of recursive waste) and the Lane et al test. (2002), leading to higher values and overestimating the final prognosis of wind power. A decrease in the average wind speed was also observed from 2003 to 2011 during six months of these years.!The spring season, often with the highest wind potential had the highest mean decrease while the season with the lowest wind potential, fall, had the opposite behavior during the studied period. By spectral analysis, performed by Fourier method, the time series of sunshine and solar radiation also showed cycles with possible ranges of influence on measurements of the solar energy potential. Such temporal variations in the data, indicate that possible locations for the wind and photovoltaic plants may be seriously affected since longterm weather fluctuations can vary significantly even at the best location selected to generate electricity. / Esta tese analisa os dados mensais das séries históricas dos ciclos de insolação, radiação solar e velocidade média dos ventos para melhorar o prognóstico de longo prazo na localização de áreas para fontes eólicas e solares de geração de potência elétrica. Como estudo de caso, tomou-se o período de dados de 1961 a 2008 para definir imprecisões de longo prazo que podem ocorrer no estado do Rio Grande do Sul, Brasil, na estimativa da tendência comportamental das variáveis meteorológicas e compará-las com dados medidos, testando assim, a homogeneidade das informações. As análises das variáveis climáticas foram realizadas através de modelos ARIMA (modelos autorregressivos integrados de média móvel), por meio da metodologia Box & Jenkins e do estudo da sazonalidade com modelos X11 ARIMA em níveis de significância estatística de 5%. Neste estudo, o período entre 1961 e 2011 indicou que os índices de insolação não foram suficientes para superar os valores verificados nas décadas de 1960 e 1970, em que os percentuais foram na maioria dos meses da ordem de -1% abaixo da média histórica. Os dados observados da insolação sugerem tendências decrescentes nas décadas de 1980 e 1990, pela presença do fenômeno global dimming sobre o estado do Rio Grande do Sul contribuindo para menores níveis de radiação solar. Foi constatada também uma possível quebra estrutural na série eólica em agosto de 2001 através do teste CUSUMQ (soma acumulada dos quadrados dos resíduos recursivos) e do teste de Lane et al. (2002), conduzindo a valores maiores e superestimando o prognóstico final do potencial eólico. Também foi constatada, redução em seis dos doze meses do ano na velocidade média dos ventos no período de 2003 a 2011. A estação da primavera, geralmente com o maior potencial eólico, indicou uma maior média de redução enquanto a estação de menor potencial eólico, o outono, mostrou um comportamento inverso para este mesmo período. Através da análise espectral, realizada pelo método de Fourier, as séries históricas de insolação e radiação solar mostraram também ciclos com amplitudes possíveis de influenciar as mensurações do potencial energético solar. Com estas variações temporais nos dados, as previsões de localização de centrais eólicas e fotovoltaicas ficam seriamente prejudicadas, uma vez que as oscilações meteorológicas de longo prazo podem variar sensivelmente na melhor localização de áreas para geração de energia elétrica.