Observations of long‐term field‐aligned flow of O<sup>+</sup> ions near the equator during summer and winter

Cladis, J. B.; Collin, H. L.

doi:10.1029/97ja01500

Cited by 6 publications

(3 citation statements)

References 19 publications

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“…On the other hand, the dawn-dusk asymmetry seen in the data is consistent with the formation of parallel potential drops, since parallel electric fields from one hemisphere to the other flow predominantly from summer to winter in the dawn sector and from winter to summer in the dusk sector (Cladis and Collin, 1997). We see most of the ion clouds in the dawn sector in the winter hemisphere.…”

Section: Upward Parallel Potential Drop At Conjugate Hemispheresupporting

confidence: 71%

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

et al. 2001

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Abstract. Data from the Astrid-2 satellite taken between April and July 1999 show several examples of dense ion clouds in the 0.1-2 keV energy range inside the inner magnetosphere, both in the northern and southern hemispheres. These inner magnetospheric ion clouds are found predominantly in the early morning sector, suggesting that they could have originated from substorm-related ion injections on the night side. However, their location and density show no correlation with Kp, and their energy-latitude dispersion is not easily reproduced by a simple particle drift model. Therefore, these ion clouds are not necessarily caused by substormrelated ion injections. Alternative explanations for the ion clouds are the direct solar wind injections and up-welling ions from the other hemisphere. These explanations do not, however, account for all of the observations.

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Section: Upward Parallel Potential Drop At Conjugate Hemispheresupporting

confidence: 71%

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

et al. 2001

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“…The particle energy stored in the inner magnetosphere is mostly sustained by energetic ions with energy ranging between hundreds of eV and hundreds of keV [ Frank , 1967; Smith and Hoffman , 1973; Williams , 1981]. There are at least four possible transport processes to explain accumulation of the energetic particles that contribute to the storm‐time ring current development: (1) convection electric field [e.g., Kavanagh et al , 1968; Chen , 1970; Wolf , 1970; Jaggi and Wolf , 1973; Ejiri , 1978], (2) substorm [e.g., Akasofu , 1968; McIlwain , 1974; Mauk and McIlwain , 1974; Konradi et al , 1975], (3) diffusion [e.g., Lyons and Schulz , 1989; Riley and Wolf , 1992] and (4) direct entry from the ionosphere into the heart of the ring current [e.g., Cladis and Collin , 1997; Sheldon et al , 1998].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear impact of plasma sheet density on the storm‐time ring current

et al. 2005

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[1] We investigated the nonlinear impact of the plasma sheet density on the total energy of the storm-time ring current by means of a numerical simulation that self-consistently solves the kinetic equation of ring current protons and the closure of the electric current between the magnetosphere and ionosphere. Results of the simulation indicate that when the convection electric field is self-consistently coupled with the ring current, the total energy of the ring current ions trapped by the Earth's magnetic field is roughly proportional to $N ps 1/2 , where N ps is the plasma sheet density. This nonlinear response results from the strengthened shielding electric field with increasing N ps . The total energy is almost proportional to N ps when using an empirical convection electric field, which is independent of the condition of the simulated ring current. An empirical relationship between N ps and the solar wind density was used to estimate time-dependent N ps . The result shows that the calculated Dst* tends to overshoot the observed one when the non-self-consistent electric field is employed. A better agreement was obtained with the self-consistent electric field. We suggest that the nonlinear response of the ring current to N ps is one of the mechanisms that impedes the growth of the storm-time ring current. Another mechanism is probably the saturation of the polar cap potential drop for high solar wind electric field.

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“…Energetic O + is also a big contributor to the ring current, particularly during large magnetic storms [e.g., Hamilton et al , 1988; Daglis et al , 1993; Collin et al , 1993; Pulkkinen et al , 2001; Fu et al , 2002]. Occasionally, low‐energy field‐aligned flows of O + (sometimes termed “zipper” events) are observed deep within the inner magnetosphere during storms [ Kaye et al , 1981; Fennell et al , 1981; Cladis and Collin , 1997; Sheldon and Spence , 1997]. Oxygen ions in the ring current are thought to be primary contributors to stable auroral red arc formation [ Kozyra et al , 1987, 1997].…”

Section: Introductionmentioning

confidence: 99%

Occurrence statistics of cold, streaming ions in the near‐Earth magnetotail: Survey of Polar‐TIDE observations

et al. 2005

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[1] Results are presented from a survey of cold ion observations in the near-Earth magnetotail using data from the Polar Thermal Ion Dynamics Experiment (TIDE). During the interval from July to December of 2001, Polar had its apogee ($9.5 R E ) near the equatorial plane in the tail region of the magnetosphere. It is shown that a lobal wind is ubiquitous in the inner tail, with low-energy (<300 eV) ions streaming from the ionosphere downtail. These lobal winds often pass through the plasma sheet, forming bidirectional streams, in addition to the unidirectional beams seen at higher magnetic latitudes. The observance of bidirectional streams is inversely, although weakly, correlated with geomagnetic activity. Bidirectional streams are interpreted as indicating the minimum size of the closed flux tube region. The reduced frequency of bidirectional streams with activity level times is consistent with the thinning of the plasma sheet during these times. It is inferred from the universality of these observations during Polar's passage through the inner tail region that the ionosphere is a continuous supplier of plasma to the near-Earth magnetosphere. The high occurrence rate of these streams means that during geomagnetic disturbances, it is not necessary to wait for outflow and magnetospheric circulation in order to supply the inner magnetosphere with ionospheric ions; these cold streams are an immediately available supply of ionospheric-origin particles.

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Observations of long‐term field‐aligned flow of O⁺ ions near the equator during summer and winter

Cited by 6 publications

References 19 publications

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

Nonlinear impact of plasma sheet density on the storm‐time ring current

Occurrence statistics of cold, streaming ions in the near‐Earth magnetotail: Survey of Polar‐TIDE observations

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Observations of long‐term field‐aligned flow of O+ ions near the equator during summer and winter

Cited by 6 publications

References 19 publications

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

Nonlinear impact of plasma sheet density on the storm‐time ring current

Occurrence statistics of cold, streaming ions in the near‐Earth magnetotail: Survey of Polar‐TIDE observations

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Observations of long‐term field‐aligned flow of O⁺ ions near the equator during summer and winter