| 1. |
- Alexeev, I. I., et al.
(författare)
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Magnetopause mapping to the ionosphere for northward IMF
- 2007
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 25:12, s. 2615-2625
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Tidskriftsartikel (refereegranskat)abstract
- We study the topological structure of the magnetosphere for northward IMF. Using a magnetospheric magnetic field model we study the high-latitude response to prolonged periods of northward IMF. For forced solar wind conditions we investigate the location of the polar cap region, the polar cap potential drop, and the field-aligned acceleration potentials, depending on the solar wind pressure and IMF B-y and B-x changes. The open field line bundles, which connect the Earth's polar ionosphere with interplanetary space, are calculated. The locations of the magnetospheric plasma domains relative to the polar ionosphere are studied. The specific features of the open field line regions arising when IMF is northward are demonstrated. The coefficients of attenuation of the solar wind magnetic and electric fields which penetrate into the magnetosphere are determined.
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| 2. |
- Blomberg, Lars G., et al.
(författare)
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Transpolar aurora : time evolution, associated convection patterns, and a possible cause
- 2005
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 23:5, s. 1917-1930
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Tidskriftsartikel (refereegranskat)abstract
- We present two event studies illustrating the detailed relationships between plasma convection, field-aligned currents, and polar auroral emissions, as well as illustrating the influence of the Interplanetary Magnetic Field's y-component on theta aurora development. The transpolar are of the theta aurorae moves across the entire polar region and becomes part of the opposite side of the auroral oval. Electric and magnetic field and precipitating particle data are provided by DMSP, while the POLAR UVI instrument provides measurements of auroral emissions. Ionospheric electrostatic potential patterns are calculated at different times during the evolution of the theta aurora using the KTH model. These model patterns are compared to the convection predicted by mapping the magnetopause electric field to the ionosphere using the Paraboloid Model of the magnetosphere. The model predicts that parallel electric fields are set up along the magnetic field lines projecting to the transpolar aurora. Their possible role in the acceleration of the auroral electrons is discussed.
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| 3. |
- Cumnock, Judy A., et al.
(författare)
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Simultaneous polar aurorae and modelled convection patterns in both hemispheres
- 2006
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Ingår i: Advances in Space Research. - : Elsevier. - 0273-1177 .- 1879-1948. ; 38:8, s. 1685-1693
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Tidskriftsartikel (refereegranskat)abstract
- We present an event study illustrating the relationships between plasma convection and polar auroral emissions, as well as illustrating the influence of the interplanetary magnetic field's y-component on theta aurora development in both hemispheres. Transpolar arcs (TPAs) are often observed during northward IMF with duskside (dawnside) formation of the TPA and dawnward (duskward) motion occurring when B-y changes from positive to negative in the northern (southern) hemisphere. POLAR UVI provides images in the northern hemisphere while DMSP provides ionospheric plasma flow and precipitating particle data in both hemispheres. Concurrent solar wind plasma and interplanetary magnetic field measurements are provided by the ACE satellite. Utilizing the satellite data as inputs, the Royal Institute of Technology (KTH) numerical model provides the high-latitude ionospheric electrostatic potential patterns in both hemispheres calculated at different times during the evolution of the theta aurora resulting from a variety of field-aligned current configurations associated with the changing global aurora. These model patterns are compared to the convection predicted by mapping the magnetopause electric field to the ionosphere using the Moscow State University's (MSU) paraboloid model of the magnetosphere. The model predicts that parallel electric fields are set up along the magnetic field lines projecting to the transpolar aurora. Their possible role in the acceleration of the auroral electrons is discussed.
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| 4. |
- Schrijver, Carolus J., et al.
(författare)
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Understanding space weather to shield society : A global road map for 2015-2025 commissioned by COSPAR and ILWS
- 2015
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 55:12, s. 2745-2807
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing appreciation that the environmental conditions that we call space weather impact the technological infrastructure that powers the coupled economies around the world. With that comes the need to better shield society against space weather by improving forecasts, environmental specifications, and infrastructure design. We recognize that much progress has been made and continues to be made with a powerful suite of research observatories on the ground and in space, forming the basis of a Sun Earth system observatory. But the domain of space weather is vast extending from deep within the Sun to far outside the planetary orbits and the physics complex including couplings between various types of physical processes that link scales and domains from the microscopic to large parts of the solar system. Consequently, advanced understanding of space weather requires a coordinated international approach to effectively provide awareness of the processes within the Sun Earth system through observation-driven models. This roadmap prioritizes the scientific focus areas and research infrastructure that are needed to significantly advance our understanding of space weather of all intensities and of its implications for society. Advancement of the existing system observatory through the addition of small to moderate state-of-the-art capabilities designed to fill observational gaps will enable significant advances. Such a strategy requires urgent action: key instrumentation needs to be sustained, and action needs to be taken before core capabilities are lost in the aging ensemble. We recommend advances through priority focus (1) on observation-based modeling throughout the Sun Earth system, (2) on forecasts more than 12 h ahead of the magnetic structure of incoming coronal mass ejections, (3) on understanding the geospace response to variable solar-wind stresses that lead to intense geomagnetically-induced currents and ionospheric and radiation storms, and (4) on developing a comprehensive specification of space climate, including the characterization of extreme space storms to guide resilient and robust engineering of technological infrastructures. The roadmap clusters its implementation recommendations by formulating three action pathways, and outlines needed instrumentation and research programs and infrastructure for each of these. An executive summary provides an overview of all recommendations.
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