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| 2. |
- Block, Lars P, et al.
(author)
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Advantages of electric circuit models for treating the substorm breakup problem
- 1998
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In: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. ; 103, s. 6913-6916
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Journal article (peer-reviewed)abstract
- It is shown, by using a circuit model for the magnetospheric current system, that the substorm breakup can be triggered either by some instability anywhere in the circuit or by a decrease in the generator emf, i.e., a northward turning of the interplanetary magnetic field.
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| 3. |
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| 4. |
- Gu, Limin
(author)
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Chinese Daycare in Cultural Change
- 1996
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In: Tidskrift för lärarutbildning och forskning. - Umeå : Dept. of Education, Umeå Univ.. - 1404-7659. ; 3:4, s. 17-44
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Licentiate thesis (other academic/artistic)
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Mishin, V M, et al.
(author)
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A study of the CDAW 9C substorm of May 3, 1986, using magnetogram inversion technique 2, and a substorm scenario with two active phases
- 1997
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In: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - 0148-0227. ; 102:A9, s. 19845-19859
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Journal article (peer-reviewed)abstract
- One of the CDAW 9C substorms is investigated in this paper using the database reported by Hones et al. and supplemented with magnetogram inversion technique (MIT) 2 data. These latter have provided information about the dynamics of the open tail magnetic Aux, current systems in the ionosphere, and the size and dynamics of the current wedge. We have identified the growth: expansion, and recovery phases of this substorm, with characteristics expected from a generally accepted scenario. However, specific signatures were observed in the interval (0919-0935) UTI i.e., between the growth and expansion phases, indicating the concurrent development of the substorm onset and corresponding instabilities in the innermost current sheet, and small-scale cross-tail current disruptions without the open tail reconnection. In addition to signatures of small-scale dipolarization, an increase of the open tail magnetic flux, and a current system of the type close to DP 2 were observed at (0919-0935) UT, which is more likely to suggest predominance of the tail-stretching process than magnetic collapse, This fact was interpreted in tel ms of a relevant simple model as a signature of the growth of the energy input from the solar wind which ensures the observable disturbance power. Hence the disturbance st (0919-0935) UT was more likely a driven one than an unloading one. The aforementioned signatures make it possible to identify the interval (0919-0935) UT as the ''phase of multiple onsets'' or: (equivalently) the ''first active phase,'' which was previously defined by Mishin [1991., and references therein] as one of the four standard phases of a typical substorm (in addition to the expansion phase). Thus the case study supports the substorm scenario with two active phases and, accordingly, with two different kinds of physics, This case study illustrates also the informativity of MIT 2 data and their ability to effectively complement the database traditionally used in substorm studies.
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| 10. |
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| 11. |
- Rothwell, P.L., et al.
(author)
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Inertial currents and substorm onsets
- 1996
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In: European Space Agency, (Special Publication) ESA SP-389. - 0379-6566. ; , s. 447-452
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Journal article (peer-reviewed)abstract
- When magnetic field lines are sufficiently stretched during the substorm growth phase, in the equatorial plane the earthward ExB ion drift velocity can become comparable to the ion gyration velocity. Under these conditions inertial currents can become quite important. Using a two-dimensional model we find that O+ ions injected from the ionosphere into the equatorial plane at high latitudes will drift eastward at radial distances less than -10 RE because the inertial drift dominates and westward at distances closer to the earth because the magnetic gradient drift dominates. The inertial eastward drift gives rise to a current which in terms of JxB is consistent with the convective deceleration of the earthward drift velocity due to higher values of B. Similarly, momentum balance requires that the convective acceleration of the westward drift velocity should be consistent with a tailward inertial current. Therefore, an equatorial current wedge system with eastward and tailward current components naturally arises from the ion dynamics. In a future paper a three-dimensional treatment will determine whether curvature drift masks the eastward inertial drift of the oxygen ions.
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| 12. |
- Rothwell, P.L, et al.
(author)
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Particle dynamics in a spatially varying electric field
- 1995
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 100, s. 14875-14885
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Journal article (peer-reviewed)abstract
- For an MHD description of a plasma a distinct separation between the macroscopic and microscopic spatial and temporal scales is assumed. In this paper we solve the particle dynamics with finite first and second spatial derivatives in the electric field. We find that (1) MHD (ideal and nonideal) becomes invalid for a sufficiently strong constant electric field gradient perpendicular to the magnetic field; (2) a sufficiently large second derivative in the electric field can cause heavy ions to become chaotically untrapped; (3) for an electric field with a constant gradient the ion drift velocity is equal to (ExB)/\textbackslashB\textbackslash(2) as long as the orbit-averaged value off is used. There are no finite currents associated with the ion drift for such an electric field; (4) perturbation technique gives a poor approximation to the ion drift velocity even for values of the second derivative that may well occur in the magnetosphere. Results 1 and 2 provide necessary criteria for the applicability of magnetospheric MHD models of spatially varying electric fields. They also predict an asymmetry in the heavy ion fluxes, a feature that could be useful in inferring magnetospheric electric field structure. We illustrate these results by application to the Harang discontinuity. It is found that if the interplanetary magnetic field swings northward under substorm growth conditions the orbits of the equatorial O+ may dramatically change due to result 2. This effect may contribute to the substorm onset process.
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| 13. |
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| 14. |
- Rouleau, C, et al.
(author)
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Kinetics and body distribution of waterborne Zn-65(II), Cd-109(II), Hg-203(II), and (CH3Hg)-Hg-203(II) in phantom midge larvae (Chaoborus americanus) and effects of complexing agents
- 1998
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In: ENVIRONMENTAL SCIENCE & TECHNOLOGY. - : AMER CHEMICAL SOC. - 0013-936X. ; 32:9, s. 1230-1236
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Journal article (other academic/artistic)abstract
- Uptake, elimination and body-distribution of waterborne Zn-65(II), Cd-109(II), Hg-203(II), and (CH3Hg)-Hg-203(II) were studied in fourth instar larvae of phantom midge, Chaoborus americanus, using a two-compartment kinetic model and whole-body autoradiogr
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