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Title: Separator reconnection at Earth's dayside magnetopause under generic northward interplanetary magnetic field conditions

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1211689
Resource Type:
Journal Article
Resource Relation:
Journal Name: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS; Journal Volume: 112; Journal Issue: A2
Country of Publication:
United States
Language:
English

Citation Formats

Dorelli, JC, Bhattacharjee, A, and Raeder, J. Separator reconnection at Earth's dayside magnetopause under generic northward interplanetary magnetic field conditions. United States: N. p., 2007. Web. doi:10.1029/2006JA011877.
Dorelli, JC, Bhattacharjee, A, & Raeder, J. Separator reconnection at Earth's dayside magnetopause under generic northward interplanetary magnetic field conditions. United States. doi:10.1029/2006JA011877.
Dorelli, JC, Bhattacharjee, A, and Raeder, J. Wed . "Separator reconnection at Earth's dayside magnetopause under generic northward interplanetary magnetic field conditions". United States. doi:10.1029/2006JA011877.
@article{osti_1211689,
title = {Separator reconnection at Earth's dayside magnetopause under generic northward interplanetary magnetic field conditions},
author = {Dorelli, JC and Bhattacharjee, A and Raeder, J},
abstractNote = {},
doi = {10.1029/2006JA011877},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS},
number = A2,
volume = 112,
place = {United States},
year = {Wed Feb 14 00:00:00 EST 2007},
month = {Wed Feb 14 00:00:00 EST 2007}
}
  • Data from the Kapuskasing and Saskatoon radars of the evolving Super Dual Auroral Radar Network (SuperDARN) HF radar network have been analyzed to study the two-dimensional structure and dynamics of dayside high-latitude ionospheric convection under northward interplanetary magnetic field (IMF) conditions. A period extending from 1600 to 2030 UT ({approximately}0900-1330 MLT) on January 10, 1994, was examined. During this interval, magnetic field data were available from the IMP 8 satellite and indicated moderately stable northward IMF conditions. For the first few hours of observation the B{sub y} component of the IMF was positive, reasonably steady, and approximately twice the magnitudemore » of B{sub z}. During this interval, the high-latitude convection images obtained with the SuperDARN radars were very similar to the distorted two-cell convection maps for positive B{sub y} as presented by Heppner and Maynard. At {approx} 1840 UT, a decrease in B{sub y} in association with an increase in B{sub z}, led to an extended period with B{sub y}{approx}B{sub z}. During this second interval the convection patterns were highly variable and even chaotic. Finally, a sharp decrease in the B{sub y} component at 1914 UT, probably in association with a rotational discontinuity in the solar wind, led to an extended period with B{sub y}<« less
  • This paper presents preliminary analysis of six flux transfer events which were observed simultaneously by IRM and CCE. IRM was able to measure magnetic fields and pressures far from the earth, while CCE made observations at the earth's magnetopause. The objective is to better understand the coupling of energy and momentum into the earth's magnetosphere, by in this case trying to better understand the processes active in flux transfer events. For three of the events the observations were made on common field lines, and IRM observed fluctuations in B[sub z] large enough to cause a south to north swing inmore » the interplanetary magnetic field (IMF). Pressure pulses were observed during two of these events. For the other three events there was no such consistent behavior of IMF direction or pressure pulses.« less
  • The authors examine the response of auroral magnetic records to the passage of an interplanetary shock at a time when the interplanetary magnetic field was northward. They restrict their attention solely to the sector within 3 hours of local magnetic midnight for a single case selected when a bursty bulk flow event was recorded in the near tail by ISEE 2. Over most of the nightside at high latitudes only a weak disturbance if any is seen. At lower latitudes a plateau is seen in the H component, coincident with the bursty bulk flow event. At 65{degrees} latitude from aboutmore » midnight to 3:00 LT a weak pair of negative bays is observed, also coincident with the bursty bulk flow event. The authors conclude that the tail and the auroral ionosphere were closely coupled during this sudden impulse, but the auroral zone disturbance appears to be mainly the brief activation of a section of the auroral electrojet rather than a classic substorm. No expansion or motion of the electrojet was observed, and the activation was no longer than that of the bursty bulk flow in the tail. 10 refs., 9 figs., 1 tab.« less
  • Spatial distribution and temporal variation of the interplanetary magnetic field (IMF) B{sub y}-dependent cusp region field-aligned currents (FACs) during quiet periods were studied by use of magnetic data observed by Magsat. The analysis was made for 11 events (each event lasts more than one and a half days) when the IMF B{sub y} component was steadily large and B{sub x} was relatively small ({vert bar}B{sub z}{vert bar} < {vert bar}B{sub y}{vert bar}). Results of the analysis of total 62 half-day periods for the IMF B{sub y}-dependent cusp region FAC are summarized as follows: (1) the IMF B{sub y}-dependent cusp regionmore » FAC is located at around 86{degree}-87{degree} invariant latitude local noon, which is more poleward than the location of the IMF B{sub z}-dependent cusp region FAC; (2) the current density of this FAC is greater than previous studies ({ge} 4 {mu}A/m{sup 2} for IMF B{sub y} = 6 nT); (3) there are two time scales for the IMF B{sub y}-dependent cusp region FAC to appear: the initial rise of the current is on a short time scale, {approximately} 10 min, and it is followed by a gradual increase on a time scale of several hours to a half day; (4) the seasonal change of this FAC is greater than that of the nightside region 1 or region 2 FACs; (5) the IMF B{sub z}-dependent cusp region FAC is not well observed around the cusp when the IMF B{sub y}-dependent cusp region FAC is intense.« less
  • On July 23, 1983, the Interplanetary Magnetic Field turned strongly northward, becoming about 22 nT for several hours. Using a combined data set of ionospheric convection measurements made by the Sondre Stromfjord incoherent scatter radar and convection inferred from Greenland magnetometer measurements, we observe the onset of the reconfiguration of the high-latitude ionospheric currents to occur about 3 min following the northward IMF encountering the magnetopause. The large-scale reconfiguration of currents, however, appears to evolve over a period of about 22 min. Using a computer model in which the distribution of field-aligned current in the polar cleft is directly determinedmore » by the strength and orientation of the interplanetary electric field, we are able to simulate the time-varying pattern of ionospheric convection, including the onset of high-latitude ''reversed convection'' cells observed to form during the interval of strong northward IMF. These observations and the simulation results indicate that the dayside polar cap electric field observed during strong northward IMF is produced by a direct electrical current coupling with the solar wind. copyright American Geophysical Union 1988« less