scholarly journals Event Studies of O + Density Variability Within Quiet‐Time Plasma Sheet

2019 ◽  
Vol 124 (6) ◽  
pp. 4168-4187 ◽  
Author(s):  
Chih‐Ping Wang ◽  
Stephen A. Fuselier ◽  
Marc Hairston ◽  
Xiao‐jia Zhang ◽  
Shasha Zou ◽  
...  
Keyword(s):  
Plasma Sheet ◽  
Event Studies ◽  
Quiet Time

Observational determination of the adiabatic index in the quiet time plasma sheet

1989 ◽  
Vol 16 (6) ◽  
pp. 563-566 ◽  
Author(s):  
C. Y. Huang ◽  
C. K. Goertz ◽  
L. A. Frank ◽  
G. Rostoker
Keyword(s):  
Plasma Sheet ◽  
Adiabatic Index ◽  
Quiet Time

Quiet-time convection electric field properties derived from keV electron measurements at the inner edge of the plasma sheet by means of GEOS-2

1982 ◽  
Vol 30 (3) ◽  
pp. 261-283 ◽  
Author(s):  
B. Hultqvist ◽  
H. Borg ◽  
L.-Ă. Holmgren ◽  
H. Reme ◽  
A. Bahnsen ◽  
...  
Keyword(s):  
Electric Field ◽  
Plasma Sheet ◽  
Quiet Time ◽  
Convection Electric Field

scholarly journals Modeling the quiet time inner plasma sheet protons

2001 ◽  
Vol 106 (A4) ◽  
pp. 6161-6178 ◽  
Author(s):  
Chih-Ping Wang ◽  
Larry R. Lyons ◽  
Margaret W. Chen ◽  
Richard A. Wolf
Keyword(s):  
Plasma Sheet ◽  
Quiet Time

scholarly journals EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere

2011 ◽  
Vol 29 (2) ◽  
pp. 299-319 ◽  
Author(s):  
T. Pitkänen ◽  
A. T. Aikio ◽  
O. Amm ◽  
K. Kauristie ◽  
H. Nilsson ◽  
...  
Keyword(s):  
High Resolution ◽  
Plasma Flow ◽  
Plasma Sheet ◽  
Velocity Shear ◽  
Optical Measurements ◽  
Return Flow ◽  
Quiet Time ◽  
Reconnection Rate ◽  
Plasma Bubble ◽  
Return Flows

Abstract. We report observations of a sequence of quiet-time Earthward bursty bulk flows (BBFs) measured by the Cluster spacecraft in the near-tail plasma sheet (XGSM ~ −12 to −14 RE) in the evening sector, and by simultaneous high-resolution measurements in the northern conjugate ionosphere by the EISCAT radars, a MIRACLE all-sky camera and magnetometers, as well as a meridian-scanning photometer (MSP) in the Scandinavian sector on 17 October 2005. The BBFs at Cluster show signatures that are consistent with the plasma "bubble" model (Chen and Wolf, 1993, 1999), e.g. deflection and compression of the ambient plasma in front of the Earthward moving bubble, magnetic signatures of a flow shear region, and the proper flows inside the bubble. In addition, clear signatures of tailward return flows around the edges of the bubble can be identified. The duskside return flows are associated with significant decrease in plasma density, giving support to the recent suggestion by Walsh et al. (2009) of formation of a depleted wake. However, the same feature is not seen for the dawnside return flows, but rather an increase in density. In the ionosphere, EISCAT and optical measurements show that each of the studied BBFs is associated with an auroral streamer that starts from the vicinity of the polar cap boundary, intrudes equatorward, brakes at 68–70° aacgm MLAT and drifts westward along the proton oval. Within the streamer itself and poleward of it, the ionospheric plasma flow has an equatorward component, which is the ionospheric manifestation of the Earthward BBF channel. A sharp velocity shear appears at the equatorward edge of a streamer. We suggest that each BBF creates a local velocity shear in the ionosphere, in which the plasma flow poleward of and inside the streamer is in the direction of the streamer and southeastward. A northwestward return flow is located on the equatorward side. The return flow is associated with decreased plasma densities both in the ionosphere and in the magnetosphere as measured by EISCAT and Cluster, respectively. In summary, we present the first simultaneous high-resolution observations of BBF return flows both in the plasma sheet and in the ionosphere, and those are in accordance with the bubble model. The results apply for the duskside return flows, but the manifestation of dawnside return flows in the ionosphere requires further studies. Finally, EISCAT measurements indicate increased nightside reconnection rate during the ~35-min period of BBFs. We suggest that the observed temporal event of IMF rotation to a more southward direction produces enhanced open flux transport to the nightside magnetotail, and consequently, the nightside reconnection rate is increased.

scholarly journals Two-dimensional quiet time equilibrium for the inner plasma sheet protons and magnetic field

2002 ◽  
Vol 29 (24) ◽  
pp. 39-1-39-4 ◽  
Author(s):  
Chih-Ping Wang ◽  
Larry R. Lyons ◽  
Margaret W. Chen ◽  
Richard A. Wolf
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
Two Dimensional ◽  
Quiet Time

scholarly journals Periodic traveling compression regions during quiet geomagnetic conditions and their association with ground Pi2

2008 ◽  
Vol 26 (11) ◽  
pp. 3341-3354 ◽  
Author(s):  
A. Keiling ◽  
F. S. Mozer ◽  
H. Rème ◽  
I. Dandouras ◽  
E. Lucek ◽  
...  
Keyword(s):  
Plasma Sheet ◽  
Time Delays ◽  
Propagation Time ◽  
Quiet Time ◽  
Inner Magnetosphere ◽  
Outer Magnetosphere ◽  
Pi2 Pulsations ◽  
Magnetic Pulsations ◽  
Magnetotail Dynamics ◽  
Time Periodic

Abstract. Recently, Keiling et al. (2006) showed that periodic (~90 s) traveling compression regions (TCRs) during a substorm had properties of Pi2 pulsations, prompting them to call this type of periodic TCRs "lobe Pi2". It was further shown that time-delayed ground Pi2 had the same period as the lobe Pi2 located at 16 RE, and it was concluded that both were remotely driven by periodic, pulsed reconnection in the magnetotail. In the study reported here, we give further evidence for this association by reporting additional periodic TCR events (lobe Pi2s) at 18 RE all of which occurred in succession during a geomagnetically very quiet, non-substorm period. Each quiet-time periodic TCR event occurred during an interval of small H-bay-like ground disturbance (<40 nT). Such disturbances have previously been identified as poleward boundary intensifications (PBIs). The small H bays were superposed by Pi2s. These ground Pi2s are compared to the TCRs in the tail lobe (Cluster) and both magnetic pulsations and flow variations at 9 RE inside the plasma sheet (Geotail). The main results of this study are: (1) Further evidence is given that periodic TCRs in the tail lobe at distances of 18 RE and ground Pi2 are related phenomena. In particular, it is shown that both had the same periodicity and occurred simultaneously (allowing for propagation time delays) strongly suggesting that both had the same periodic source. Since the TCRs were propagating Earthward, this source was located in the outer magnetosphere beyond 18 RE. (2) The connection of periodic TCRs and ground Pi2 also exists during very quiet geomagnetic conditions with PBIs present in addition to the previous result (Keiling et al., 2006) which showed this connection during substorms. (3) Combining (1) and (2), we conclude that the frequency of PBI-associated Pi2 is controlled in the outer magnetosphere as opposed to the inner magnetosphere. We propose that this mechanism is pulsed reconnection based on previous results which combined modeled results and observations of substorm-related periodic TCRs and ground Pi2. (4) We show that TCRs with small compression ratios (ΔB/B<1%) can be useful in the study of magnetotail dynamics and we argue that other compressional fluctuations with ΔB/B<1% (without having all of the characteristic signatures of TCRs) seen in the tail lobe could possibly be related to the same mechanism that generates TCR with ΔB/B>1% (which are more commonly studied). (5) Finally, it is noted that both quiet time and substorm-related periodic TCRs had remarkably similar periods in spite of the drastically different geomagnetic conditions prevailing during the events which poses the important question of what causes this periodicity under these different conditions.

scholarly journals Shear flow instabilities in the Earth's magnetotail

1996 ◽  
Vol 14 (8) ◽  
pp. 786-793
Author(s):  
R. V. Reddy ◽  
G. S. Lakhina
Keyword(s):  
Shear Flow ◽  
Plasma Sheet ◽  
Flow Instability ◽  
Mhd Equations ◽  
Surface Mode ◽  
Quiet Time ◽  
Central Plasma ◽  
Oscillating Boundary ◽  
Central Plasma Sheet ◽  
Shear Flow Instability

Abstract. Shear flow instability is studied in the Earth's magnetotail by treating plasma as compressible. A dispersion relation is derived from the linearized MHD equations using the oscillating boundary conditions at the inner central plasma sheet/outer central plasma sheet (OCPS) interface and OCPS/plasma-sheet boundary layer (PSBL) interface, whereas the surface-mode boundary condition is used at the PSBL/lobe interface. The growth rates and the real frequencies are obtained numerically for near-Earth (∣X∣~10–15 RE) and far-Earth (∣X∣~100 RE) magnetotail parameters. The periods and wavelengths of excited modes depend sensitively on the value of plasma-sheet half thickness, L, which is taken as L=5 RE for quiet time and L=1 RE for disturbed time. The plasma-sheet region is found to be stable for constant plasma flows unless MA3>1.25, where MA3 is the Alfvén Mach number in PSBL. For near-Earth magnetotail, the excited oscillations have periods of 2–20 min (quiet time) and 0.5–4 min (disturbed time) with typical transverse wavelengths of 2–30 RE and 0.5–6.5 RE, respectively; whereas for distant magnetotail, the analysis predicts the oscillation periods of ~8–80 min for quiet periods and 2–16 min for disturbed periods.

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