On the Low Energy (< keV) O+ Ion Outflow directly into the Inner Magnetosphere

Author(s):  
Matina Gkioulidou ◽  
Shin Ohtani ◽  
Don Mitchell ◽  
Harlan Spence

&lt;p&gt;The development of low energy (&lt; keV) O+ ions in the inner magnetosphere is a crucial issue for various aspects of magnetospheric dynamics: i) Recent studies have suggested that low energy O+ can be locally accelerated to few keV energies inside geosynchronous orbit, and thus can constitute a significant source of the storm-time ring current O+ that could dominate the energy density during storms, ii) Mass loaded densities are important for accurate location of the plasmapause, which, in turn, is necessary for meaningful calculation of the field line resonance radial frequency profiles of ULF hydromagnetic waves in plasmasphere, iii) since O+ is only of ionospheric origin, its outflow from ionosphere into the magnetosphere is a manifestation of fundamental processes concerning energy and mass flow within the coupled Magnetosphere &amp;#8211; Ionosphere system. Although a lot of progress has been made on O+ outflow at high latitudes and its subsequent transport and acceleration within the magnetotail and plasma sheet, the source of low-energy O+ within the inner magnetosphere remains a compelling open question. The Helium Oxygen Proton and Electron (HOPE) mass spectrometer instrument aboard Van Allen Probes, which move in highly elliptical, low inclination orbits with apogee of 5.8 RE, has repeatedly detected field aligned flux enhancements of eV to hundreds of eV O+ ions, which indicate O+ outflow directly into the inner magnetosphere. We systematically investigate, throughout the duration of the Van Allen Probes mission (2012 &amp;#8211; 2019), the occurrence of such events with respect to L and MLT, the dependence of their directionality (bi-directional or unidirectional) and the lowest and highest energies involved on L, MLT and MLAT. We categorize the outflow events with respect to plasmapause location (when its determination is possible) and identify whether there is enhancement of O+ density. This categorization is important because if the outflows occur close to the plasmapause location, and depending on the density enhancement they cause, they could be responsible for the formation of O+ torus, whose source has been under debate for years. Finally, in order to identify the physical processes that lead to the ionospheric outflow, we also examine whether there are dipolarizations and/or enhancements of the field-aligned poynting flux associated with these outflow events.&lt;/p&gt;

2019 ◽  
Vol 124 (1) ◽  
pp. 405-419 ◽  
Author(s):  
Matina Gkioulidou ◽  
S. Ohtani ◽  
A. Y. Ukhorskiy ◽  
D. G. Mitchell ◽  
K. Takahashi ◽  
...  

2013 ◽  
Vol 31 (9) ◽  
pp. 1569-1578 ◽  
Author(s):  
M. Yamauchi ◽  
I. Dandouras ◽  
H. Rème ◽  
R. Lundin ◽  
L. M. Kistler

Abstract. Using Cluster Ion Spectrometry (CIS) data from the spacecraft-4 perigee traversals during the 2001–2006 period (nearly 500 traversals after removing those that are highly contaminated by radiation belt particles), we statistically examined the local time distribution of structured trapped ions at sub- to few-keV range as well as inbound–outbound differences of these ion signatures in intensities and energy–latitude dispersion directions. Since the Cluster orbit during this period was almost constant and approximately north–south symmetric at nearly constant local time near the perigee, inbound–outbound differences are attributed to temporal developments in a 1–2 h timescale. Three types of structured ions at sub- to few keV range that are commonly found in the inner magnetosphere are examined: – Energy–latitude dispersed structured ions at less than a few keV, – Short-lived dispersionless ion stripes at wide energy range extending 0.1–10 keV, – Short-lived low-energy ion bursts at less than a few hundred eV. The statistics revealed that the wedge-like dispersed ions are most often observed in the dawn sector (60% of traversals), and a large portion of them show significant enhancement during the traversals at all local times. The short-lived ion stripes are predominantly found near midnight, where most stripes are significantly enhanced during the traversals and are associated with substorm activities with geomagnetic AL < −300 nT. The low-energy bursts are observed at all local times and under all geomagnetic conditions, with moderate peak of the occurrence rate in the afternoon sector. A large portion of them again show significant enhancement or decay during the traversals.


2011 ◽  
Vol 38 (8) ◽  
pp. n/a-n/a ◽  
Author(s):  
A. D. DeJong ◽  
J. L. Burch ◽  
J. Goldstein ◽  
A. J. Coates ◽  
F. Crary

2017 ◽  
Vol 122 (2) ◽  
pp. 1789-1802 ◽  
Author(s):  
M. H. Denton ◽  
G. D. Reeves ◽  
B. A. Larsen ◽  
R. H. W. Friedel ◽  
M. F. Thomsen ◽  
...  

2019 ◽  
Vol 46 (15) ◽  
pp. 8597-8606 ◽  
Author(s):  
A. J. Hull ◽  
C. C. Chaston ◽  
J. W. Bonnell ◽  
J. R. Wygant ◽  
C. A. Kletzing ◽  
...  

2017 ◽  
Vol 35 (4) ◽  
pp. 869-877 ◽  
Author(s):  
Rikard Slapak ◽  
Maria Hamrin ◽  
Timo Pitkänen ◽  
Masatoshi Yamauchi ◽  
Hans Nilsson ◽  
...  

Abstract. Recent studies strongly suggest that a majority of the observed O+ cusp outflows will eventually escape into the solar wind, rather than be transported to the plasma sheet. Therefore, an investigation of plasma sheet flows will add to these studies and give a more complete picture of magnetospheric ion dynamics. Specifically, it will provide a greater understanding of atmospheric loss. We have used Cluster spacecraft 4 to quantify the H+ and O+ total transports in the near-Earth plasma sheet, using data covering 2001–2005. The results show that both H+ and O+ have earthward net fluxes of the orders of 1026 and 1024 s−1, respectively. The O+ plasma sheet return flux is 1 order of magnitude smaller than the O+ outflows observed in the cusps, strengthening the view that most ionospheric O+ outflows do escape. The H+ return flux is approximately the same as the ionospheric outflow, suggesting a stable budget of H+ in the magnetosphere. However, low-energy H+, not detectable by the ion spectrometer, is not considered in our study, leaving the complete magnetospheric H+ circulation an open question. Studying tailward flows separately reveals a total tailward O+ flux of about 0. 5 × 1025 s−1, which can be considered as a lower limit of the nightside auroral region O+ outflow. Lower velocity flows ( < 100 km s−1) contribute most to the total transports, whereas the high-velocity flows contribute very little, suggesting that bursty bulk flows are not dominant in plasma sheet mass transport.


2016 ◽  
Vol 121 (12) ◽  
pp. 11,698-11,713 ◽  
Author(s):  
Y. Nakayama ◽  
Y. Ebihara ◽  
S. Ohtani ◽  
M. Gkioulidou ◽  
K. Takahashi ◽  
...  

2009 ◽  
Vol 5 (S267) ◽  
pp. 327-327
Author(s):  
V. Cracco ◽  
S. Ciroi ◽  
F. Di Mille ◽  
L. Vaona ◽  
P. Rafanelli ◽  
...  

AbstractIonization cones are one of the most important pieces of evidence supporting the AGN unified model (Antonucci & Miller 1985; Urry & Padovani 1995). Until now, the physical processes at work in the cones are not completely understood. A still open question concerns the origin of the gas. To study the origin of the ionized gas, we first selected a sample of nearby (z<0.03) Seyfert galaxies showing extended [O iii] λ5007 emission. We then observed these galaxies with the MultiPupil Fiber Spectrograph (MPFS) at the 6-m telescope of the Special Astrophysical Observatory (Russia). Here we present very preliminary results on the properties of the narrow-line region (NLR) of the intermediate Seyfert galaxy Mrk 6.


Space Weather ◽  
2005 ◽  
Vol 3 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. L. Roeder ◽  
M. W. Chen ◽  
J. F. Fennell ◽  
R. Friedel

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