scholarly journals Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event

2000 ◽  
Vol 18 (12) ◽  
pp. 1584-1598 ◽  
Author(s):  
K. A. McWilliams ◽  
T. K. Yeoman ◽  
S. W. H. Cowley
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Flux Tube ◽  
Convection Velocity ◽  
Hf Radar ◽  
Two Dimensional ◽  
Plasma Convection ◽  
Transfer Event ◽  
Ionospheric Convection ◽  
Flux Transfer

Abstract. Line-of-sight Doppler velocities from the SuperDARN CUTLASS HF radar pair have been combined to produce the first two-dimensional vector measurements of the convection pattern throughout the ionospheric footprint of a flux transfer event (a pulsed ionospheric flow, or PIF). Very stable and moderate interplanetary magnetic field conditions, along with a preceding prolonged period of northward interplanetary magnetic field, allow a detailed study of the spatial and the temporal evolution of the ionospheric response to magnetic reconnection. The flux tube footprint is tracked for half an hour across six hours of local time in the auroral zone, from magnetic local noon to dusk. The motion of the footprint of the newly reconnected flux tube is compared with the ionospheric convection velocity. Two primary intervals in the PIF's evolution have been determined. For the first half of its lifetime in the radar field of view the phase speed of the PIF is highly variable and the mean speed is nearly twice the ionospheric convection speed. For the final half of its lifetime the phase velocity becomes much less variable and slows down to the ionospheric convection velocity. The evolution of the flux tube in the magnetosphere has been studied using magnetic field, magnetopause and magnetosheath models. The data are consistent with an interval of azimuthally propagating magnetopause reconnection, in a manner consonant with a peeling of magnetic flux from the magnetopause, followed by an interval of anti-sunward convection of reconnected flux tubes.Key words: Magnetospheric physics (magnetosphere · ionosphere interactions; plasma convection; solar wind · magnetosphere interactions)

scholarly journals Measuring the dayside reconnection rate during an interval of due northward interplanetary magnetic field

2004 ◽  
Vol 22 (12) ◽  
pp. 4243-4258 ◽  
Author(s):  
G. Chisham ◽  
M. P. Freeman ◽  
I. J. Coleman ◽  
M. Pinnock ◽  
M. R. Hairston ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Interplanetary Magnetic Field ◽  
Line Length ◽  
Hf Radar ◽  
Plasma Convection ◽  
Ionosphere Plasma ◽  
Reconnection Region ◽  
Field Lines ◽  
First Time

Abstract. This study presents, for the first time, detailed spatiotemporal measurements of the reconnection electric field in the Northern Hemisphere ionosphere during an extended interval of northward interplanetary magnetic field. Global convection mapping using the SuperDARN HF radar network provides global estimates of the convection electric field in the northern polar ionosphere. These are combined with measurements of the ionospheric footprint of the reconnection X-line to determine the spatiotemporal variation of the reconnection electric field along the whole X-line. The shape of the spatial variation is stable throughout the interval, although its magnitude does change with time. Consequently, the total reconnection potential along the X-line is temporally variable but its typical magnitude is consistent with the cross-polar cap potential measured by low-altitude satellite overpasses. The reconnection measurements are mapped out from the ionosphere along Tsyganenko model magnetic field lines to determine the most likely reconnection location on the lobe magnetopause. The X-line length on the lobe magnetopause is estimated to be ~6–11 RE in extent, depending on the assumptions made when determining the length of the ionospheric X-line. The reconnection electric field on the lobe magnetopause is estimated to be ~0.2mV/m in the peak reconnection region. Key words. Space plasma physics (Magnetic reconnection) – Magnetospheric physics (Magnetopause, cusp and boundary layers) – Ionosphere (Plasma convection)

scholarly journals Simultaneous observations of magnetopause flux transfer events and of their associated signatures at ionospheric altitudes

2004 ◽  
Vol 22 (6) ◽  
pp. 2181-2199 ◽  
Author(s):  
K. A. McWilliams ◽  
G. J. Sofko ◽  
T. K. Yeoman ◽  
S. E. Milan ◽  
D. G. Sibeck ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Southern Hemisphere ◽  
High Latitude ◽  
Field Conditions ◽  
Transfer Event ◽  
Flux Transfer Events ◽  
Subsolar Point ◽  
Reconnection Site ◽  
Flux Transfer

Abstract. An extensive variety of instruments, including Geotail, DMSP F11, SuperDARN, and IMP-8, were monitoring the dayside magnetosphere and ionosphere between 14:00 and 18:00 UT on 18 January 1999. The location of the instruments provided an excellent opportunity to study in detail the direct coupling between the solar wind, the magnetosphere, and the ionosphere. Flux transfer events were observed by Geotail near the magnetopause in the dawn side magnetosheath at about 4 magnetic local time during exclusively northward interplanetary magnetic field conditions. Excellent coverage of the entire dayside high-latitude ionosphere was achieved by the Northern Hemisphere SuperDARN radars. On the large scale, temporally and spatially, the dayside magnetosphere convection remained directly driven by the interplanetary magnetic field, despite the highly variable interplanetary magnetic field conditions, including long periods of northward field. The SuperDARN radars in the dawn sector also measured small-scale temporally varying convection velocities, which are indicative of flux transfer event activity, in the vicinity of the magnetic footprint of Geotail. DMSP F11 in the Southern Hemisphere measured typical cusp precipitation simultaneously with and magnetically conjugate to a single flux transfer event signature detected by Geotail. A study of the characteristics of the DMSP ion spectrogram revealed that the source plasma from the reconnection site originated downstream of the subsolar point. Detailed analyses of locally optimised coordinate systems for individual flux transfer events at Geotail are consistent with a series of flux tubes protruding from the magnetopause, and originating from a high-latitude reconnection site in the Southern Hemisphere. This high-latitude reconnection site agrees with plasma injected away from the subsolar point. This is the first simultaneous and independent determination from ionospheric and space-based data of the location of magnetic reconnection.

scholarly journals A flux transfer event observed at the magnetopause by the Equator-S spacecraft and in the ionosphere by the CUTLASS HF radar

1999 ◽  
Vol 17 (6) ◽  
pp. 707-711 ◽  
Author(s):  
D. A. Neudegg ◽  
T. K. Yeoman ◽  
S. W. H. Cowley ◽  
G. Provan ◽  
G. Haerendel ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Transient Flow ◽  
Hf Radar ◽  
Data Set ◽  
Transfer Event ◽  
Interplanetary Physics ◽  
Wind Spacecraft ◽  
Flux Transfer ◽  
Field Lines

Abstract. Observations of a flux transfer event (FTE) have been made simultaneously by the Equator-S spacecraft near the dayside magnetopause whilst corresponding transient plasma flows were seen in the near-conjugate polar ionosphere by the CUTLASS Finland HF radar. Prior to the occurrence of the FTE, the magnetometer on the WIND spacecraft ~226 RE upstream of the Earth in the solar wind detected a southward turning of the interplanetary magnetic field (IMF) which is estimated to have reached the subsolar magnetopause ~77 min later. Shortly afterwards the Equator-S magnetometer observed a typical bipolar FTE signature in the magnetic field component normal to the magnetopause, just inside the magnetosphere. Almost simultaneously the CUTLASS Finland radar observed a strong transient flow in the F region plasma between 78° and 83° magnetic latitude, near the ionospheric region predicted to map along geomagnetic field lines to the spacecraft. The flow signature (and the data set as a whole) is found to be fully consistent with the view that the FTE was formed by a burst of magnetopause reconnection.Key words. Interplanetary physics (ionosphere-magnetosphere interaction) · Magnetospheric physics (magnetopause · cusp · and boundary layers; solar wind-magnetosphere interactions)

scholarly journals Central polar cap convection response to short duration southward Interplanetary Magnetic Field

2000 ◽  
Vol 18 (8) ◽  
pp. 887-896 ◽  
Author(s):  
P. T. Jayachandran ◽  
J. W. MacDougall
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Short Duration ◽  
Initial Response ◽  
Plasma Convection ◽  
Polar Cap ◽  
Ionosphere Plasma ◽  
Rapid Transition ◽  
Convection Speed ◽  
A Chain

Abstract. Central polar cap convection changes associated with southward turnings of the Interplanetary Magnetic Field (IMF) are studied using a chain of Canadian Advanced Digital Ionosondes (CADI) in the northern polar cap. A study of 32 short duration (~1 h) southward IMF transition events found a three stage response: (1) initial response to a southward transition is near simultaneous for the entire polar cap; (2) the peak of the convection speed (attributed to the maximum merging electric field) propagates poleward from the ionospheric footprint of the merging region; and (3) if the change in IMF is rapid enough, then a step in convection appears to start at the cusp and then propagates antisunward over the polar cap with the velocity of the maximum convection. On the nightside, a substorm onset is observed at about the time when the step increase in convection (associated with the rapid transition of IMF) arrives at the polar cap boundary.Key words: Ionosphere (plasma convection; polar ionosphere) - Magnetospheric physics (solar wind - magnetosphere interaction)

Two-Dimensional Hybrid-PIC Simulation of Magnetic Sail Including Interplanetary Magnetic Field

2012 ◽  
Vol 60 (1) ◽  
pp. 31-39
Author(s):  
Masaharu MATSUMOTO ◽  
Yoshihiro KAJIMURA ◽  
Hideyuki USUI ◽  
Ikkoh FUNAKI ◽  
Iku SHINOHARA
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Two Dimensional ◽  
Pic Simulation
Sign in / Sign up

Export Citation Format

Share Document