dot
Detailansicht
Katalogkarte GBA
Katalogkarte ISBD
Suche präzisieren
Drucken
Download RIS
Hier klicken, um den Treffer aus der Auswahl zu entfernen
Titel In-situ observation of ULF wave activities associated with substorm expansion phase onset and current disruption
VerfasserIn J. Liang, W. W. Liu, E. F. Donovan, E. Spanswick
Medientyp Artikel
Sprache Englisch
ISSN 0992-7689
Digitales Dokument URL
Erschienen In: Annales Geophysicae ; 27, no. 5 ; Nr. 27, no. 5 (2009-05-13), S.2191-2204
Datensatznummer 250016536
Publikation (Nr.) Volltext-Dokument vorhandencopernicus.org/angeo-27-2191-2009.pdf
 
Zusammenfassung
In this paper we present two substorm events with coordinated ground-based and in-situ THEMIS observations, and focus our interest on the wave activities in Pi1 and Pi2 bands from minutes before the substorm expansion phase (EP) onset to minutes after the local current disruption (CD). We find that Pi2 band (40–100 s) wave appears 1–2 min before the substorm onset and last over the entire EP interval, while higher-frequency wave within Pi1 band (10–30 s) emerges within few tens of seconds after the EP onset, intensifies during the local CD, and fades afterwards. The pre-onset Pi2 waves are attributed to a ballooning mode which acts as the seed perturbation to the substorm EP onset process. The azimuthal wavenumber estimated from the Doppler shift nature of the ballooning mode is consistent with the longitudinal "wavelength" inferred from the onset auroral structures. The Pi1 waves appearing within few tens of seconds after the EP onset are interpreted as supportive of a two-fluid instability mode of thin current sheet investigated in an accompanying paper (Liu and Liang, 2009). During the local CD, broadband wave activities from Pi2 band to well above the ion gyrofrequency are observed, suggesting the coexistence of various plasma instabilities featuring different frequency ranges.
 
Teil von