TY - GEN

T1 - Bursty bulk flows and their ionospheric footprints

AU - Sergeev, VA

PY - 2004

Y1 - 2004

N2 - The bursty bulk flows (BBFs), which provide a major contribution to the Earthward convection in the high-beta plasma sheet region of the magnetotail, are nearly uniformly distributed in distance between 40-50 Re and the inner magnetosphere. Most of them are now confirmed to be plasma bubbles, the underpopulated plasma tubes with a smaller value of plasma tube entropy (pVgamma). Many BBFs are visible in the ionosphere due to the associated plasma precipitation and 3d-electric currents, which provides an excellent possibility to study the global dynamics of BBFs by observing their auroral footprints. A number of recent studies, including studies of associated precipitation, convection and field-aligned currents indicate that main mechanism providing a bright optical image of the BBF is the electric discharge (field-aligned electron acceleration) from the dusk flank of the BBF where the intense upward FAC is generated. The auroral signatures have variable forms, with auroral streamers being the most reliable and easily indentified BBF signature. The picture of BBFs emerging from these results corresponds to the powerful (up to several tens kV in one jet) sporadic narrow (2-3 Re) plasma jets propagating in the tail as the plasma bubbles, which are probably born in the impulsive reconnection process but filtered and modified by the interchange process. Penetration of BBFs to less than 6.6 Re distance in the inner magnetosphere was frequently observed, with indications of flow jet diversion and braking (with associated pressure increase and magnetic field compression). Such interaction also creates long-lived drifting plasma structures, particularly those which can be related to torch and omega-type auroras. Role of BBFs in generating other types of auroral structures is briefly discussed.

AB - The bursty bulk flows (BBFs), which provide a major contribution to the Earthward convection in the high-beta plasma sheet region of the magnetotail, are nearly uniformly distributed in distance between 40-50 Re and the inner magnetosphere. Most of them are now confirmed to be plasma bubbles, the underpopulated plasma tubes with a smaller value of plasma tube entropy (pVgamma). Many BBFs are visible in the ionosphere due to the associated plasma precipitation and 3d-electric currents, which provides an excellent possibility to study the global dynamics of BBFs by observing their auroral footprints. A number of recent studies, including studies of associated precipitation, convection and field-aligned currents indicate that main mechanism providing a bright optical image of the BBF is the electric discharge (field-aligned electron acceleration) from the dusk flank of the BBF where the intense upward FAC is generated. The auroral signatures have variable forms, with auroral streamers being the most reliable and easily indentified BBF signature. The picture of BBFs emerging from these results corresponds to the powerful (up to several tens kV in one jet) sporadic narrow (2-3 Re) plasma jets propagating in the tail as the plasma bubbles, which are probably born in the impulsive reconnection process but filtered and modified by the interchange process. Penetration of BBFs to less than 6.6 Re distance in the inner magnetosphere was frequently observed, with indications of flow jet diversion and braking (with associated pressure increase and magnetic field compression). Such interaction also creates long-lived drifting plasma structures, particularly those which can be related to torch and omega-type auroras. Role of BBFs in generating other types of auroral structures is briefly discussed.

KW - magnetotail

KW - plasma sheet

KW - convection

KW - bursty bulk flows

KW - aurora

KW - EARTH PLASMA SHEET

KW - HIGH-SPEED FLOWS

KW - FIELD-ALIGNED CURRENT

KW - RAPID FLUX TRANSPORT

KW - ART. NO. 1106

KW - AURORAL STREAMERS

KW - MAGNETIC RECONNECTION

KW - GEOTAIL OBSERVATIONS

KW - PARTICLE INJECTIONS

KW - INNER MAGNETOTAIL

M3 - статья в сборнике материалов конференции

SN - 1-4020-2766-4

T3 - NATO SCIENCE SERIES, SERIES II: MATHEMATICS, PHYSICS AND CHEMISTRY

SP - 289

EP - 306

BT - MULTISCALE PROCESSES IN THE EARTH'S MAGNETOSPHERE: FROM INTERBALL TO CLUSTER

A2 - Sauvaud, JA

A2 - Nemecek, Z

PB - Springer Nature

Y2 - 9 September 2003 through 12 September 2003

ER -