Research output: Contribution to journal › Article › peer-review
Auroral signatures of transient processes in the outer magnetosphere. / Popescu, D.; Sauvaud, J. A.; Stenuit, H.; Delcourt, D. C.; Sergeev, V. A.; Brittnacher, M.; Parks, G. K.; Mukai, T.; Kokubun, S.; Kovrazhkin, R. A.
In: Advances in Space Research, Vol. 30, No. 12, 12.2002, p. 2701-2711.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Auroral signatures of transient processes in the outer magnetosphere
AU - Popescu, D.
AU - Sauvaud, J. A.
AU - Stenuit, H.
AU - Delcourt, D. C.
AU - Sergeev, V. A.
AU - Brittnacher, M.
AU - Parks, G. K.
AU - Mukai, T.
AU - Kokubun, S.
AU - Kovrazhkin, R. A.
PY - 2002/12
Y1 - 2002/12
N2 - We present an analysis of sporadic and recurrent injections of magnetospheric ions in the midnight auroral oval during substorms and of the associated ionospheric ion outflows. The source of plasma sheet precipitating ions is determined using a simple method, based on the measured relation between the ion inverse velocity and time (l = v × t). This method is applied here to two typical passes of the Interball-Auroral (IA) satellite at distances of ∼ 3 R E above the auroral regions. Substorm related ion injections are shown to be mainly due to time of flight effects. In contrast with particle trajectory computations (Sauvaud et al., 1999), the im,erse velocity method does not require magnetic and electric field models and can thus be used systematically for the detection of time of flight dispersed ion structures (TDIS). This allowed us to build a large database of TDIS events and to perform a statistical analysis of their spatial distribution. For the cases presented here the source region of the injected ions is found at radial distances from 18 to 30 RE near the equatorial magnetosphere. At Interball altitudes (∼ 3 R E ), ion injections detected at the poleward boundary of the nighside auroral oval are associated with shear Alfvén waves superimposed over large-scale quasi-static current structures. We show that the most poleward TDIS are collocated with a large outflow of ionospheric H + and O + displaying pitch-angle distributions peaked in the pitch-angle range 90°-120°. These ions are thus accelerated perpendicularly to the magnetic field not only in the main auroral acceleration region but also up to at least 3 R E . The expanding auroral bulge thus constitutes a significant source of H + and O + ions for the mid-tail magnetosphere.
AB - We present an analysis of sporadic and recurrent injections of magnetospheric ions in the midnight auroral oval during substorms and of the associated ionospheric ion outflows. The source of plasma sheet precipitating ions is determined using a simple method, based on the measured relation between the ion inverse velocity and time (l = v × t). This method is applied here to two typical passes of the Interball-Auroral (IA) satellite at distances of ∼ 3 R E above the auroral regions. Substorm related ion injections are shown to be mainly due to time of flight effects. In contrast with particle trajectory computations (Sauvaud et al., 1999), the im,erse velocity method does not require magnetic and electric field models and can thus be used systematically for the detection of time of flight dispersed ion structures (TDIS). This allowed us to build a large database of TDIS events and to perform a statistical analysis of their spatial distribution. For the cases presented here the source region of the injected ions is found at radial distances from 18 to 30 RE near the equatorial magnetosphere. At Interball altitudes (∼ 3 R E ), ion injections detected at the poleward boundary of the nighside auroral oval are associated with shear Alfvén waves superimposed over large-scale quasi-static current structures. We show that the most poleward TDIS are collocated with a large outflow of ionospheric H + and O + displaying pitch-angle distributions peaked in the pitch-angle range 90°-120°. These ions are thus accelerated perpendicularly to the magnetic field not only in the main auroral acceleration region but also up to at least 3 R E . The expanding auroral bulge thus constitutes a significant source of H + and O + ions for the mid-tail magnetosphere.
KW - SHEET ION INJECTIONS
KW - PLASMA SHEET
KW - FIELD
KW - BULGE
KW - SPACECRAFT
KW - EXPANSION
KW - SUBSTORMS
KW - BOUNDARY
KW - DYNAMICS
KW - REGION
UR - http://www.scopus.com/inward/record.url?scp=0036944701&partnerID=8YFLogxK
U2 - 10.1016/S0273-1177(02)80388-X
DO - 10.1016/S0273-1177(02)80388-X
M3 - Article
VL - 30
SP - 2701
EP - 2711
JO - Advances in Space Research
JF - Advances in Space Research
SN - 0273-1177
IS - 12
T2 - D3 5/PSRBI Symposium of the COSPAR Scientific Commission D held at the 33rd COSPAR Assembly
Y2 - 1 July 2000
ER -
ID: 60576694