Bursty bulk flows and their ionospheric footprints

Research outputpeer-review

Abstract

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.

Original languageEnglish
Title of host publicationMULTISCALE PROCESSES IN THE EARTH'S MAGNETOSPHERE: FROM INTERBALL TO CLUSTER
EditorsJA Sauvaud, Z Nemecek
PublisherSpringer Nature
Pages289-306
Number of pages18
ISBN (Print)1-4020-2766-4
Publication statusPublished - 2004
EventNATO Advanced Research Workshop on Multiscale Processes in the Earth's Magnetosphere - From Interball to Cluster - Prague
Duration: 9 Sep 200312 Sep 2003

Publication series

NameNATO SCIENCE SERIES, SERIES II: MATHEMATICS, PHYSICS AND CHEMISTRY
PublisherSPRINGER
Volume178

Conference

ConferenceNATO Advanced Research Workshop on Multiscale Processes in the Earth's Magnetosphere - From Interball to Cluster
CountryCzech Republic
CityPrague
Period9/09/0312/09/03

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