TY - JOUR

T1 - Relationship between substorm auroras and processes in the near-earth magnetotail

AU - Yahnin, A. G.

AU - Despirak, I. V.

AU - Lubchich, A. A.

AU - Kozelov, B. V.

AU - Dmitrieva, N. P.

AU - Shukhtina, M. A.

AU - Biernat, H. K.

PY - 2006

Y1 - 2006

N2 - Although the auroral substorm has been long regarded as a manifestation of the magnetospheric substorm, a direct relation of active auroras to certain magnetospheric processes is still debatable. To investigate the relationship, we combine the data of the UV imager onboard the Polar satellite with plasma and magnetic field measurements by the Geotail spacecraft. The poleward edge of the auroral bulge, as determined from the images obtained at the LHBL passband, is found to be conjugated with the region where the oppositely directed fast plasma flows observed in the near-Earth plasma sheet during substorms are generated. We conclude that the auroras forming the bulge are due to the near-Earth reconnection process. This implies that the magnetic flux through the auroral bulge is equal to the flux dissipated in the magnetotail during the substorm. Comparison of the magnetic flux through the auroral bulge with the magnetic flux accumulated in the tail lobe during the growth phase shows that these parameters have the comparable values. This is a clear evidence of the loading-unloading scheme of substorm development. It is shown that the area of the auroral bulge developing during substorm is proportional to the total (magnetic plus plasma) pressure decrease in the magnetotail. These findings stress the importance of auroral bulge observations for monitoring of substorm intensity in terms of the magnetic flux and energy dissipation.

AB - Although the auroral substorm has been long regarded as a manifestation of the magnetospheric substorm, a direct relation of active auroras to certain magnetospheric processes is still debatable. To investigate the relationship, we combine the data of the UV imager onboard the Polar satellite with plasma and magnetic field measurements by the Geotail spacecraft. The poleward edge of the auroral bulge, as determined from the images obtained at the LHBL passband, is found to be conjugated with the region where the oppositely directed fast plasma flows observed in the near-Earth plasma sheet during substorms are generated. We conclude that the auroras forming the bulge are due to the near-Earth reconnection process. This implies that the magnetic flux through the auroral bulge is equal to the flux dissipated in the magnetotail during the substorm. Comparison of the magnetic flux through the auroral bulge with the magnetic flux accumulated in the tail lobe during the growth phase shows that these parameters have the comparable values. This is a clear evidence of the loading-unloading scheme of substorm development. It is shown that the area of the auroral bulge developing during substorm is proportional to the total (magnetic plus plasma) pressure decrease in the magnetotail. These findings stress the importance of auroral bulge observations for monitoring of substorm intensity in terms of the magnetic flux and energy dissipation.

KW - auroral substorm

KW - magnetotail

KW - plasma sheet

KW - magnetic reconnection

KW - MAGNETIC-FIELD

KW - PLASMA SHEET

KW - ULTRAVIOLET IMAGER

KW - FLOW BURSTS

KW - MAGNETOSPHERE

KW - BRIGHTENINGS

KW - SATELLITE

KW - MECHANISM

KW - DYNAMICS

KW - MODEL

U2 - 10.1007/s11214-006-5884-4

DO - 10.1007/s11214-006-5884-4

M3 - Обзорная статья

VL - 122

SP - 97

EP - 106

JO - Space Science Reviews

JF - Space Science Reviews

SN - 0038-6308

IS - 1-4

ER -