352 research outputs found

    The earth's magnetosphere

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    The following aspects of the earth's magnetosphere were discussed: general structure, magnetic field merging and magnetospheric convection, time-varying convection and magnetospheric substorms, magnetic storms, and comparative magnetospheres. Solar flares and the magnetospheres of Mercury, Venus, Mars, Jupiter, Saturn, and Uranus were also described

    Relativistic electrons and whistlers in Jupiter's magnetosphere

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    The path-integrated gain of parallel propagating whistlers driven unstable by an anisotropic distribution of relativistic electrons in the stable trapping region of Jupiter's inner magnetosphere was computed. The requirement that a gain of 3 e-foldings of power balance the power lost by imperfect reflection along the flux tube sets a stably-trapped flux of electrons which is close to the non-relativistic result. Comparison with measurements shows that observed fluxes are near the stably-trapped limit, which suggests that whistler wave intensities may be high enough to cause significant diffusion of electrons accounting for the observed reduction of phase space densities. A crude estimate of the wave intensity necessary to diffuse electrons on a radial diffusion time scale yields a lower limit for the magnetic field fluctuation intensity

    Lossy radial diffusion of relativistic Jovian electrons

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    The radial diffusion equation with synchrotron losses was solved by the Laplace transform method for near-equatorially mirroring relativistic electrons. The evolution of a power law distribution function was found and the characteristics of synchrotron burn-off are stated in terms of explicit parameters for an arbitrary diffusion coefficient. Emissivity from the radiation belts of Jupiter was studied. Asymptotic forms for the distribution in the strong synchrotron loss regime are provided

    Magnetospheric electrons

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    Coupling of source, transport, and sink processes produces a fairly accurate model for the macroscopic structure and dynamics of magnetospheric electrons. Auroral electrons are controlled by convective transport from a plasma sheet source coupled with a precipitation loss due to whistler and electrostatic plasma turbulence. Outer and inner zone electrons are governed by radial diffusion transport from convection and acceleration sources external to the plasmapause and by parasitic precipitation losses arising from cyclotron and Landau interactions with whistler and ion cyclotron turbulence

    Is Jupiter's magnetosphere like a pulsar's or earth's?

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    The application of pulsar physics to determine the magnetic structure in the planet Jupiter outer magnetosphere is discussed. A variety of theoretical models are developed to illuminate broad areas of consistency and conflict between theory and experiment. Two possible models of Jupiter's magnetosphere, a pulsar-like radial outflow model and an earth-like convection model, are examined. A compilation of the simple order of magnitude estimates derivable from the various models is provided

    Polarization of the auroral electrojet

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    Precipitation from the inner edge of the electron plasma sheet creates a density maximum in the auroral oval ionosphere, which in turn leads to Hall and Pedersen conductance maxima. A uniform westward convection electric field is imposed upon the lower ionosphere previous to polarization. Field-aligned currents flow into the ionosphere equatorward, and out poleward, of the Hall conductance maximum. As the convection field and ionospheric density increase during substorm growth phase, the field-aligned current densities eventually reach an instability threshold, beyond which anomalous resistance produces field-aligned electric fields. The partial blockage of the field-aligned currents produces an equatorward electric field and therefore a partial Cowling conductivity in the lower ionosphere

    Electrostatic instability of ring current protons beyond the plasmapause during injection events

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    The stability of ring current protons with an injection spectrum modeled by an m = 2 mirror distribution function was examined for typical ring current parameters. It was found that the high frequency loss cone mode can be excited at wave numbers K lambda sub Di about = to 0.1 to 0.5, at frequencies omega about = to (0.2 to 0.6) omega sub pi and with growth rates up to gamma/omega about = to 0.03. These waves interact with the main body of the proton distribution and propagate nearly perpendicular to the local magnetic field. Cold particle partial densities tend to reduce the growth rate so that the waves are quenched at or near to the plasmapause boundary. Wave e-folding lengths are comparable to 0.1 R sub e, compared to the value of about 4 R sub e found for ion cyclotron waves at the same plasma conditions

    Historical and Future Role of Wilmar Palm Oil in Deforestation of Indonesian Borneo

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    Borneo is one of the most biologically diverse locations on Earth, with thousands of endemic and rare species forming unique and intricate relationships throughout the ecosystems. Orangutans, elephants, leopards, tigers, rhinos, and many more species call this island their home, although population levels for all of the mentioned species have been in seriously decline over recent decades. The loss of primary rainforest that provides the most critical habitat for these species has occurred at the highest rate that has ever been seen on Earth, leading to extreme land conversion and greenhouse gas producing operations. The primary driver of these actions are palm oil plantation companies that operate throughout Borneo, with the largest and most detrimental supplier being Wilmar International Limited. This paper reviews the actions and policies introduced by Wilmar to curb their deforestation practices as well as the role of national policy and enforcement capacity from the government to aid in this endeavor. There is considerable evidence presented in this paper that demonstrate a lack of commitment and enforcement to environmental pledges along with corruption, mismanagement, and conflicting directives within the administration of Wilmar and the Indonesian government have enabled continuous loss of primary rainforest. It is concluded that stricter commitment with proportional consequences are needed in the environmental law sector, and ecotourism is presented as the best opportunity to develop a sustainable economy in Borneo that will preserve the rainforests

    A unified theory of stable auroral red arc formation at the plasmapause

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    A theory is proposed that SAR-arcs are generated at the plasmapause as a consequence of the turbulent dissipation of ring current energy. During the recovery phase of a geomagnetic storm, the plasmapause expands outward into the symmetric ring current. When the cold plasma densities reach about 100/cu cm, ring current protons become unstable and generate intense ion cyclotron wave turbulence in a narrow region 1/2 earth radius wide (just inside the plasmapause). Approximately one-half of the ring current energy is dissipated into wave turbulence which in turn is absorbed through a Landau resonant interaction with plasma spheric electrons. The combined thermal heat flux to the ionosphere due to Landau absorption of the wave energy and proton-electron Coulomb dissipation is sufficient to drive SAR-arcs at the observed intensities. It is predicted that the arcs should be localized to a narrow latitudinal range just within the stormtime plasmapause. They should occur at all local times and persist for the 10 to 20 hour duration of the plasma-pause expansion

    Finite-larmor-radius Analysis of Laminar Collisionless Shocks

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    Laminar collisionless fast and slow shock wave theory by finite-Larmor-radius hydromagnetic fluid equation
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