Substorm introduction of ≤ 1‐keV magnetospheric ions into the inner plasmasphere

Newell, P. T.; Meng, C.‐I.

doi:10.1029/ja091ia10p11133

Cited by 25 publications

(25 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In other words, the observed wedge-like energylatitude dispersed sub-keV ions may directly reflect nightside electromagnetic disturbances. In this sense, they are probably the same as the regionally isolated sub-keV plasma sheetlike ions precipitating in the plasmasphere (Shelley et al, 1972;Sauvaud et al, 1981;Chappel et al, 1982;Newell and Meng, 1986). The latter is also considered to be of substorm origin.…”

Section: Introductionmentioning

confidence: 91%

“…Using low-altitude DMSP F6 and F7 satellites, Newell and Meng (1986) demonstrated that sub-keV ion precipitation in the late morning subauroral region (∼08:30 MLT) is strongly correlated with the K p index with some hours of time delay, and the enhanced precipitation may last a day. Both observations are in good agreement with the simulation by Ebihara et al (2001).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Sub-keV ring current ions as the tracer of substorm injection

Yamauchi

Lundin

2006

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. The dynamics of the energy-latitude dispersed sub-keV trapped ions inside the ring current region, the so-called wedge-like dispersions structure, were statistically studied using Viking satellite data. Probabilities with/without these signatures at various local times in the dayside are obtained in terms of different time-lags from the substorm activity monitored by the AE index. The structure appears in the early morning sector within a few hours after the substorm, and it slowly propagates eastward while decaying with a time scale of several hours. The result qualitatively confirmed the previous model that the wedge-like dispersions are originated from past substorm-related plasma injections into the nightside ring current region, and that the dispersion is formed when these injected plasma slowly moves eastward to the dayside by the drift motion (E×B (eastward), grad-|B| (westward), and curvature (westward) drifts). However, the appearance of the structure is twice or three times faster than the model prediction, and some structure reaches even to the evening sector. The results indicate that the start location of the drift is not as far as midnight and that the drift speed is slightly faster than the model prediction. The former means that the substorm-related increase of hot plasma in the ring current region shifts or extends to the early morning sector for large substorms, and the latter means that the substantial electric field driving the sub-keV ion drift is slightly different from the model field. We also detected the evacuating effect starting right after the substorm (or storm) onset. The electric field imposed in the dayside magnetosphere seems to remove the remainder of trapped ions.

show abstract

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Sub-keV ring current ions as the tracer of substorm injection

Yamauchi

Lundin

2006

Ann. Geophys.

View full text Add to dashboard Cite

show abstract

“…Using the Aureol-1 satellite (altitude 400 $ 2500 km), Sauvaud et al [1981] demonstrated that sub-keV ion precipitation in the subauroral region increases some hours after substorm injection in the early morning (0000-0600 MLT) sector. Using the low-altitude DMSP F6 and F7 satellites, Newell and Meng [1986] demonstrated that sub-keV ion precipitation in the late morning (0830 MLT) subauroral region is strongly correlated with the Kp index with some hours of time delay, and the enhanced precipitation may last a day. Using the Viking satellite, Yamauchi and Lundin [2006] statistically showed that these wedge-like dispersed subkeV ions are related to the past AE activity but are not directly related to the past or present Dst activity, although they are located in the ring current region.…”

Section: Introductionmentioning

confidence: 99%

“…[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%

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

et al. 2006

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

“…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

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

Substorm introduction of ≤ 1‐keV magnetospheric ions into the inner plasmasphere

Cited by 25 publications

References 40 publications

Sub-keV ring current ions as the tracer of substorm injection

Sub-keV ring current ions as the tracer of substorm injection

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

Contact Info

Product

Resources

About