Dentre os planetas do Sistema Solar, Júpiter se destaca por seu tamanho, quantidade de satélites naturais, intenso campo magnético e colossal magnetosfera, atraindo por isso a atenção da humanidade desde a Antiguidade. Com a descoberta de emissões de rádio oriundas de Júpiter e do controle parcial dessas emissões por parte de satélites Jovianos, um novo cenário atraiu atenção ao planeta: a interação eletrodinâmica entre o campo magnético de Júpiter e os satélites Io, Europa, Ganimedes e Calisto, que propicia esse controle. Aqui, apresentamos brevemente o planeta Júpiter e sua magnetosfera, o que se sabe sobre a interação Júpiter-satélites, e algumas características dos satélites Galileanos. Solar tamanho naturais magnetosfera Antiguidade Jovianos Io Europa Calisto Aqui Júpitersatélites, Júpitersatélites satélites, Júpiter-satélites Galileanos

Among the planets in the Solar System, Jupiter stands out because of its large dimensions, vast number of orbiting natural satellites, intense magnetic field and immense magnetosphere. For those reasons, Jupiter has drawn attention to itself since ancient times. Upon the discovery of radio emissions from Jupiter and of their partial control by Jovian satellites, a new scenario emerged: an electromagnetic interaction between the Jovian magnetic field and the satellites Io, Europa, Ganymede and Callisto, which enables that control. In this work, we briefly present Jupiter and its magnetosphere, what it is known about the Jupiter-satellite interaction, and some important characteristics of each one of the Galilean satellites. System dimensions magnetosphere reasons times emerged Io Europa Callisto work Jupitersatellite satellite

Este trabalho consiste em uma introdução às magnetosferas planetárias do Sistema Solar. Apresenta-se uma descrição geral da configuração das magnetosferas dos oito planetas do Sistema Solar e de sua formação pela interação de seu ambiente eletromagnético com o fluxo do vento solar. As magnetosferas planetárias são do tipo intrínseco (Mercúrio, Terra, Júpiter, Saturno, Urano, Netuno) quando o planeta possui um campo magnético intrínseco e a interação ocorre entre o vento solar e o campo planetário, com possíveis contribuições do plasma planetário; e induzida (Vênus e Marte) quando a interação ocorrer entre o fluxo do vento solar e a atmosfera superior/ionosfera do planeta. Um exemplo de medidas in-situ em uma magnetosfera também é apresentado com os dados de campo magnético da sonda Cassini em Saturno.

An introduction to the solar system planetary magnetospheres is presented. First the process of formation of the magnetosphere by the interaction of solar wind with an electromagnetic planetary obstacle is shown. Next, a general description of magnetosphere regions is presented. Finally, a short description of the solar system eight planetary magnetospheres is given. Planetary magnetospheres are of two types: intrinsic (Mercury, Earth, Jupiter, Saturn, Uranus, Neptune), when the planet has an active and intrinsic magnetic field and the interaction creating the magnetosphere occurs between the solar wind and the planetary field, with contributions of the planetary plasma; and induced (Venus and Mars), when the planet lacks an internal field, and it is the interaction between the solar wind and the planetary atmosphere/ionosphere that forms the magnetosphere. An example of in-situ observations at a planetary magnetosphere is presented with magnetic field data from the Cassini mission at Saturn.

Este trabalho apresenta uma introdução à propagação das ondas de choque não colisionais no espaço interplanetário. Inicialmente, são apresentados conceitos básicos envolvendo a propagação de informação em gases ordinários e em plasmas, os modos de ondas presentes num plasma e o seu escarpamento levando a formação de ondas de choque. A seguir são introduzidos alguns tipos de choques presentes no espaço interplanetário: frentes de choque planetárias, choques transientes devido às remanescentes de ejeções coronais de massa e choques corrotantes devido à interação de feixes rápido e lento do vento solar. Os choques também podem ser classificados quanto à direção de propagação - se afastando do Sol ou se propagando em direção ao Sol - e se são originários devido ao escarpamento de ondas magnetossônicas do modo lento ou rápido. Finalmente, um exemplo de observação de parâmetros de um choque transiente frontal rápido, com dados medidos no vento solar próximo a Terra e de seus efeitos na magnetosfera terrestre é apresentado.

An introduction to the collisionless shock waves propagating through the interplanetary space is presented. Basic concepts related to the propagation of information in ordinary gases and plasmas are reviewed. The wave modes in plasma and their steepening to shock waves are discussed. The shocks found in interplanetary space - planetary bow shocks, transient shocks driven by interplanetary coronal mass ejections and recurrent shocks due to the interaction of high-speed and low-speed solar wind streams are also discussed. Shocks can also be classified according to their propagation direction - away or toward the sun (forward and reverse shocks) and according if they are fast or slow mode magnetosonic waves steepened (fast and slow shocks). Finally, an example of calculated parameters for a transient interplanetary shock observed in solar wind near earth and its magnetospheric effects is presented.

Geomagnetic storms are intervals of time when a sufficiently intense and long-lasting interplanetary convection electric field leads, through a substantial injection of energy into the magnetosphere-ionosphere system, to an intensified ring current, strong enough to exceed some key threshold of the quantifying storm time Dst index. We have studied all the 9 great magnetic storms (peak Dst < -200 nT) observed during the rise and maximum of solar cycle 23 (from 1997 to early 2001), in order to identify their solar and interplanetary causes. Apart of one storm occurred during the period without observations from the Solar and Heliospheric Observatory (SOHO), all of them were related to coronal mass ejections observed by the Large Angle and Spectroscopic Coronagraph (LASCO). The sources of interplanetary southward magnetic field, Bs, responsible for the occurrence of the storms were related to the intensified shock/sheath field, interplanetary magnetic cloud's field, or the combination of sheath-cloud or sheath-ejecta field. It called our attention the fact that one of the events was related to a slow CME, with CME expansion speed not greater than 550 km/s. The purpose of this paper is to address the main sources of large geomagnetic disturbances using the current satellite capability available. As a general conclusion, we found that shock/sheath compressed fields are the most important interplanetary causes of great magnetic storms during this period.

In this work we present a comparison between the solar origins of two solar-terrestrial connection events occurring on April 1999 and February 2000, respectively. On April 13 (1999), a coronal mass ejection (CME) appeared for the first time in LASCO-C2 coronagraph field of view at 03:30 UT. The possible solar disc source of this CME was located at coordinates N25 E05, and it consisted on flaring activity together with a filament eruption as seen in EIT images. The geomagnetic storm with a Dst peak of -91 nT registered on April, 17 was attributed to this solar surface activity. On February 8, 9 and 10 (2000) three Earth-directed halo CMEs were recorded by LASCO coronagraphs. The interaction of two of them caused the intense interplanetary geomagnetic storm registered on February 12 (Dst = -110 nT). The CMEs detected on February 8 and 10 were launched from AR 8858 and the source of the activity was attributed to two solar flares of X-ray class M1.3 and C7.3 respectively. The CME detected on February 9 was originated in AR 8853 and flaring activity was also identified as the solar source for this event. In this study we discuss the solar origins of the events that gave rise to coronal and interplanetary disturbances and as a consequence produced geomagnetic activity at the Earth. This work is part of a complete study that is searching the solar origin, the interplanetary aspects and the magnetospheric effects of these events.

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 for upstream and downstream sides of the shocks were calculated, and the parameter variations through the shock were determined. Applications of the Rankine-Hugoniot equations were made, obtaining shock speeds and Alfvenic Mach number. Static and dynamic pressures variations through the shocks were also calculated. Every parameter have larger variation through the shock in solar maximum than in solar minimum, with exception of the proton density. The intensity of shocks relative to the interplanetary medium, quantified by the Alfvenic Mach Number, is observed to be similar in solar maximum and minimum. It could be explained because, during solar maximum, in despite of the higher shock speeds, the Alfvenic speed of the interplanetary medium is higher than in solar minimum.

A Lei de Beer da transferência radiativa tem grande aplicação em problemas atmosféricos que envolvam valores de radiação solar direta. Uma síntese da física da atenuação da radiação solar pela atmosfera e da derivação da lei de Beer é apresentada neste trabalho. São apresentadas aplicações da lei de Beer no cálculo do espectro de radiação solar direta na superfície terrestre, na região do ultravioleta, considerando condições de céu limpo e apenas espalhamento Rayleigh e absorção molecular. O método de Langley foi aplicado a dados de radiação ultravioleta solar de banda larga (0,32-0,40 mim) obtidos em Santa Maria, Rio Grande do Sul, no ano de 1994, como um exemplo ilustrativo da obtenção da irradiância no topo da atmosfera e da espessura óptica atmosférica para a banda utilizada.

The Beer's law has important utilizations in the atmosphere problems, when the direct solar radiation component isinvolved. In this work a summary of physical principles in atmospheric extinction of radiation and in the Beer's law derivation is presented. Also are presented some utilizations of the Beer's law in atmosphere: the calculation of the direc solar radiation ultraviolet spectrum at ground level, considering clear-sky conditions and attenuation only by Rayleigh scattering and molecular absorption. Also the Langley's method is applied to direct broadband solar radiation (0,32-0,40 mum) measured at Santa Maria, Rio Grande do Sul, in 1994, to obtain the iradiance at the top of atmosphere and the atmospheric optical depth.

Séries temporais de radiação UV-B, biologicamente ativa, obtidas em vários locais no Brasil, em Punta Arenas no Chile e em La Paz na Bolívia são apresentadas. O quadro atual de mudança atmosférica, principalmente a tendência global de redução no ozônio total, fez surgir na comunidade científica preocupações quanto a um possível aumento na intensidade da radiação ultravioleta (UV) solar na superfície terrestre. Nesse contexto, o Instituto Nacional de Pesquisas Espaciais-INPE opera uma rede de medidores do tipo Biômetro, radiômetros especialmente projetados para medir a radiação UV causadora de efeitos danosos à saúde humana, a radiação UV-B Eritema, desde o início dos anos 1990. Analisam-se neste trabalho as séries temporais de máxima dose diária de radiação UV-B Eritema obtidas com o Biômetro, estudando-se a variação sazonal e calculando-se o Índice UV. Os maiores valores do Índice UV são encontrados nas regiões de La Paz, Campo Grande e Natal. A radiação UV-B apresentou uma forte dependência da latitude geográfica e da altitude, conforme esperado. Os Índices UV atingiram valores próximos a 15 em La Paz, e acima de 12 em Natal e Campo Grande no período de verão. Também é apresentado o resultado de um experimento para medir a radiação UV-B difusa realizado em Cachoeira Paulista em 24 e 25 de novembro de 1998. A radiação difusa representa pelo menos 45% da radiação global para o UV-B Eritema.

Time series of biologically active UV-B radiation observed at sites in Brazil, and at La Paz, Bolívia and Punta Arenas, Chile, are presented. With the ozone depletion occurring in the earth's atmosphere, increases of UV-B radiation are expected. Since 1991, the National Institute for Space Research- INPE, has been acquiring data on biologically active solar UV radiation (Erythemal UV), at ground level. A network of radiometers to measure UV-B radiation has been used. The seasonal variations and an average UV-Index calculation is presented. The regions of La Paz, Campo Grande and Natal have the higher UV-B intensities. The UV-B radiation presented a dependency with geographical latitude and altitude, as expected. The UV-Index for summer was close to 15 at La Paz and above 12 for Campo Grande and Natal. The experiment to measure UV-B diffuse radiation showed that diffuse radiation is at least 45% of global radiation in the Erythemal UV-B radiation range.