Antiparallel reconnection as a possible source of highand low-latitude boundary layers

2003 ◽  
pp. 139-148 ◽  
Author(s):  
A. Fedorov ◽  
E. Budnik ◽  
H. Stenuit ◽  
T. Moreau ◽  
J.-A. Sauvaud
Keyword(s):  
Boundary Layers ◽  
Low Latitude

Interconnection of high-latitude and low-latitude boundary layers when IMF BY is dominant

2002 ◽  
Vol 30 (12) ◽  
pp. 2771-2779 ◽  
Author(s):  
A Fedorov ◽  
E Budnik ◽  
J.-A Sauvaud
Keyword(s):  
Boundary Layers ◽  
High Latitude ◽  
Low Latitude

scholarly journals GEOTAIL observation of tilted X-line formation during flux transfer events (FTEs) in the dayside magnetospheric boundary layers

2004 ◽  
Vol 22 (8) ◽  
pp. 2907-2916
Author(s):  
M. Nowada ◽  
T. Sakurai ◽  
T. Mukai
Keyword(s):  
Boundary Layers ◽  
Flux Tube ◽  
Diffusion Region ◽  
Current Layer ◽  
Ion Distribution ◽  
Low Latitude ◽  
Flux Transfer Events ◽  
The North ◽  
Magnetospheric Boundary ◽  
Flux Transfer

Abstract. The magnetic field and plasma structures during two successive crossings of the subsolar magnetospheric boundary layers (i.e. MagnetoPause Current Layer (MPCL) and Low-Latitude Boundary Layer (LLBL)) under the southward-dawnward IMF are examined on the basis of the data obtained by the GEOTAIL spacecraft. A significant and interesting feature is found, that is, Flux Transfer Events (FTEs) occur in association with the formation of the tilted X-line. During the first inbound MPCL/LLBL crossing, the ion velocity enhancement (in particular, the Vl component negatively increases) can be observed in association with simultaneous typical bipolar signature (positive followed by negative) in the Bn component. In addition, a clear D-shaped ion distribution whose origin is the magnetosheath can also be found in the dawnward direction. A few minutes later, the satellite experiences outbound MPCL crossing. The negative enhancement of the Vm component can be found as well as the positive enhancement of the Vl component. Simultaneously, a typical bipolar signature with the polarity (negative followed by positive) opposite that observed in the first encounter can also be observed. The ions from the magnetosheath flow predominantly in the duskward direction, although the D-shaped ion distribution cannot be observed. These results indicate that the satellite initially observes one part of a reconnected flux tube formed by FTEs whose magnetospheric side is anchored to the Southern Hemisphere. The ions confined in this partial flux tube are flowing in the south-dawnward direction. Then, the satellite observes the other part of the reconnected flux tube whose magnetospheric side is anchored to the Northern Hemisphere. The ions confined in this flux tube flow dominantly in the north-duskward direction. Furthermore, it can be considered that the second MPCL crossing is a direct cut through the diffusion region of FTEs because the LLBL is absent in the vicinity of the MPCL. On the basis of these results, it can be concluded that the satellite was passing near the tilted X-line. The information obtained through this study is expected to be of great use in discriminating between the anti-parallel (steady-state) reconnection and tilted X-line models on the dayside MPCL.

scholarly journals Statistical study of the location and size of the electron edge of the Low-Latitude Boundary Layer as observed by Cluster at mid-altitudes

2006 ◽  
Vol 24 (10) ◽  
pp. 2645-2665 ◽  
Author(s):  
Y. V. Bogdanova ◽  
C. J. Owen ◽  
A. N. Fazakerley ◽  
B. Klecker ◽  
H. Rème
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Boundary Layers ◽  
Statistical Study ◽  
High Energy ◽  
Closed Field ◽  
Low Latitude ◽  
Field Lines ◽  
Low Latitude Boundary Layer ◽  
The Imf

Abstract. The nature of particle precipitations at dayside mid-altitudes can be interpreted in terms of the evolution of reconnected field lines. Due to the difference between electron and ion parallel velocities, two distinct boundary layers should be observed at mid-altitudes between the boundary between open and closed field lines and the injections in the cusp proper. At lowest latitudes, the electron-dominated boundary layer, named the "electron edge" of the Low-Latitude Boundary Layer (LLBL), contains soft-magnetosheath electrons but only high-energy ions of plasma sheet origin. A second layer, the LLBL proper, is a mixture of both ions and electrons with characteristic magnetosheath energies. The Cluster spacecraft frequently observe these two boundary layers. We present an illustrative example of a Cluster mid-altitude cusp crossing with an extended electron edge of the LLBL. This electron edge contains 10–200 eV, low-density, isotropic electrons, presumably originating from the solar wind halo population. These are occasionally observed with bursts of parallel and/or anti-parallel-directed electron beams with higher fluxes, which are possibly accelerated near the magnetopause X-line. We then use 3 years of data from mid-altitude cusp crossings (327 events) to carry out a statistical study of the location and size of the electron edge of the LLBL. We find that the equatorward boundary of the LLBL electron edge is observed at 10:00–17:00 magnetic local time (MLT) and is located typically between 68° and 80° invariant latitude (ILAT). The location of the electron edge shows a weak, but significant, dependence on some of the external parameters (solar wind pressure, and IMF BZ- component), in agreement with expectations from previous studies of the cusp location. The latitudinal extent of the electron edge has been estimated using new multi-spacecraft techniques. The Cluster tetrahedron crosses the electron and ion boundaries of the LLBL/cusp with time delays of 1–40 min between spacecraft. We reconstruct the motion of the electron boundary between observations by different spacecraft to improve the accuracy of the estimation of the boundary layer size. In our study, the LLBL electron edge is distinctly observed in 87% of mid-altitude LLBL/cusp crossings with clear electron and ion equatorward boundaries equivalent to 35% of all LLBL/cusp crossings by Cluster. The size of this region varied between 0°–2° ILAT with a median value of 0.2° ILAT. Generally, the size of the LLBL electron edge depends on the combination of many parameters. However, we find an anti-correlation between the size of this region and the strength of the IMF, the absolute values of the IMF BY- and BZ-components and the solar wind dynamic pressure, as is expected from a simple reconnection model for the origin of this region.

Progress report on 21-cm observations at low latitude between longitudes (l 11) 0° and 66°

1967 ◽  
Vol 31 ◽  
pp. 177-179
Author(s):  
W. W. Shane
Keyword(s):  
Preliminary Report ◽  
Progress Report ◽  
Galactic Centre ◽  
Low Latitude ◽  
The Third ◽  
Introductory Lecture ◽  
Centre Region

In the course of several 21-cm observing programmes being carried out by the Leiden Observatory with the 25-meter telescope at Dwingeloo, a fairly complete, though inhomogeneous, survey of the regionl11= 0° to 66° at low galactic latitudes is becoming available. The essential data on this survey are presented in Table 1. Oort (1967) has given a preliminary report on the first and third investigations. The third is discussed briefly by Kerr in his introductory lecture on the galactic centre region (Paper 42). Burton (1966) has published provisional results of the fifth investigation, and I have discussed the sixth in Paper 19. All of the observations listed in the table have been completed, but we plan to extend investigation 3 to a much finer grid of positions.

Low‐Latitude Whistler‐Mode and Higher‐Latitude Z‐mode Emission at Jupiter Observed by Juno

2020 ◽  
Author(s):  
J. D. Menietti ◽  
T. F. Averkamp ◽  
M. Imai ◽  
W. S. Kurth ◽  
G. B. Clark ◽  
...  
Keyword(s):  
Low Latitude ◽  
Whistler Mode
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