Structures of Sub-Kev Ions Inside the Ring Current Region

Yamauchi, M.; Lundin, R.; Eliasson, L.; Winningham, D.; Rème, H.; Vallat, C.; Dandouras, I.; team, Cluster-CIS

doi:10.1029/155gm05

Cited by 9 publications

(35 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One can also recognize that this isolated dense plasma region has several wedge-like energy dispersions overlapping each other, but the entire region is clearly separated in energy range from the ordinary (>5 keV) component of the ring current ions. Although the separation is clearer in the postnoon sector than in the morning sector according to the Viking observations (both Figures 1a and 1b are postnoon traversals), this population is predominantly found at morning-to-prenoon sectors [Yamauchi et al, 2005] and thus has a different local-time distribution from the ordinary ring current component [e.g., Collin et al, 1993].…”

Section: Introductionmentioning

confidence: 94%

“…[2] Satellites traversing inside dayside ring current region frequently detect dense trapped sub-keV ions far equatorward of the auroral region [Sauvaud et al, 1981;Newell and Meng, 1986;Yamauchi et al, 1996aYamauchi et al, , 1996bYamauchi et al, , 2005Ebihara et al, 2001]. These trapped ions are energy-latitude dispersed in mostly wedge-like forms [Yamauchi et al, 1996a].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Source location of the wedge‐like dispersed ring current in the morning sector during a substorm

et al. 2006

Self Cite

View full text Add to dashboard Cite

[1] Source of wedge-like dispersed sub-keV ring current ions (wedge-like structure) is investigated using Cluster CIS data. Statistics from nearly 550 traversals show that the wedge-like structure with upper energy extending to ordinary energy of ring current is found mostly in the morning sector whereas those limited within sub-keV range are found mostly in the noon-to-afternoon sector. The former is most likely the original form of the latter. With this knowledge, the Cluster traversal on 21 October 2001 turned out to be a unique observation that reveals the formation of the wedge-like structure. Spacecraft 1 and 4 detected a wedge-like structure of 0.1 $ 10 keV protons at 2350 UT, while spacecraft 3 did not detect it 10 min before in the same magnetic flux tube. With the observed electric field of less than 3 mV/m, this fact indicates that the dispersion started within half an hour. Pitch angle distributions of the wedge-like structure is in most cases double conic-like butterfly distributions, but the wedge-like dispersed oxygen ions during the 21 October 2001 event flow mainly from one direction (from Northern Hemisphere) without a loss cone. With its characteristic energy of 0.05 $ 0.3 keV, these oxygen ions originate from the Northern Hemisphere about 20 $ 30 min before the observation. Both the dispersion analysis and the oxygen ion tracing suggest that the observed wedge-like structure is formed in the late morning sector during the latest substorm that started at 2310 UT. Possible mechanisms of the morning source are discussed.Citation: Yamauchi, M., et al. (2006), Source location of the wedge-like dispersed ring current in the morning sector during a substorm,

show abstract

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Source location of the wedge‐like dispersed ring current in the morning sector during a substorm

et al. 2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the eastward drifting energy domain, wedge-like energy-dispersed sub-keV ion structure, so called the wedgelike structure, is widely observed in the morning to noon sectors (Quinn and McIlwain, 1979;Sauvaud et al, 1981;Newell et al, 1986;Yamauchi et al, 1996Yamauchi et al, , 2005Ebihara et al, 2001). In Viking and Cluster observation, the wedgelike structure is classified into three major energy-latitude dispersion patterns, increasing energy with latitude ("ordinary"), decreasing energy with latitude ("reversed"), and decreasing energy toward both high latitude and low latitude from a certain latitude ("bridge-like").…”

Section: Introductionmentioning

confidence: 99%

Dual source populations of substorm-associated ring current ions

et al. 2009

Self Cite

View full text Add to dashboard Cite

Abstract. Sources of low-energy ring current ions in the early morning sector (eastward drifting energy domain of about <5 keV) are examined using both statistical analyses and numerical tracing methods (phase-space mapping and simulation). In about 90% of Cluster perigee traversals at 02∼07 local time, these low-energy ring current ions have dual ion populations: one is wedge-like energy-dispersed ions, and the other is a band-like ions over different latitudes in a narrow energy range at the upper energy threshold of the wedge-like energy-dispersed ions. Both components are most likely created during past substorm activities. Numerical tracing results strongly suggest that these two components have different sources with different temperatures and elapsed times. The band-like part most likely comes from ions with plasma sheet temperature (∼1 keV), and the energy-dispersed part most likely comes from cold ions (temperature <0.1 keV). The source density of the cold component (0.2∼0.5×10 6 /m 3 ) is slightly less than that of the hot component (0.5×10 6 /m 3 ), while Cluster observation shows slightly higher density for the wedge-like part than the low-energy band-like part. The hot source component also explains the observed high-energy (>10 keV) ions drifting westward after adiabatic energization in the nightside under time-varying electric field. The wedge-like part has much shorter elapsed time, i.e., less charge-exchange loss, than the band-like part.

show abstract

“…The former has been reported in Yamauchi et al (1996aYamauchi et al ( , 2005, and this type of energy-latitude dispersion can be understood as a signature of drifting ions several hours after the substorm injections (Ebihara et al, 2001).…”

Section: Multiple Heavy Ion Dispersion Eventmentioning

confidence: 81%

“…Although the simulation needs to be improved to include mass separation during the drift, the basic signature (e.g. dispersion curve and pitch-angle distribution) should be preserved according to the Cluster observation of sub-keV ring current ions (Yamauchi et al, 2005). This wedge-like signature is quite different from the observed energy-latitude dispersion.…”

Section: Midday Heavy Ion Injection Eventmentioning

confidence: 99%

Unusual heavy ion injection events observed by Freja

et al. 2005

Self Cite

View full text Add to dashboard Cite

Abstract. Heavy ion injection events (registered in the C+/N+/O+ mass channel) into the ionosphere at 1700 km height are surveyed using the Swedish-German Freja satellite data. Heavy ion injections from the inner magnetosphere are mostly found in the nightside sector with a few exceptions that occur on the dayside. We report on these exceptional cases, particularly two specific events which seem to have a different generation/transport mechanism of heavy ions from the majority of cases: 1) mono-energetic heavy ion injection near local noon with oxygen first and protons later; and 2) a multiple heavy ion dispersion event at 9 MLT. Both events are unique without any similar events in terms of dispersion pattern during the more than 2 years of the entire Freja operation, and these events are found during the main phase of major magnetic storms (peak D st is −144 nT and −105 nT). The first event is probably of dayside origin but the exact mechanism to make both energy filter and mass filter is unknown. The second event can be traced back to one localized energization of dense oxygen with strong pitch-angle anisotropy within 1000 km distance from the spacecraft.

show abstract

Structures of Sub-Kev Ions Inside the Ring Current Region

Cited by 9 publications

References 19 publications

Source location of the wedge‐like dispersed ring current in the morning sector during a substorm

Source location of the wedge‐like dispersed ring current in the morning sector during a substorm

Dual source populations of substorm-associated ring current ions

Unusual heavy ion injection events observed by Freja

Contact Info

Product

Resources

About