Change search
ReferencesLink to record
Permanent link

Direct link
On the relation between solar wind, pseudobreakups, and substorms
KTH, Superseded Departments, Alfvén Laboratory.ORCID iD: 0000-0002-0349-0645
KTH, Superseded Departments, Alfvén Laboratory.ORCID iD: 0000-0003-1270-1616
2004 (English)In: Journal of Geophysical Research, ISSN 0148-0227, Vol. 109, no A12Article in journal (Refereed) Published
Abstract [en]

A statistical study of pseudobreakups and substorms is performed using Polar UV images from a 3-month period in winter 1998-1999. Data from the ACE solar wind monitor are examined in order to determine the influence of solar wind parameters on the occurrence of different substorm and pseudobreakup types. The results confirm that the IMF clock angle and the amount of solar wind energy flux control the strength of a substorm. The majority of large substorms appear when the IMF is strongly southward and the solar wind energy flux is high. Most small substorms occur during weakly positive or zero IMF B-z and low solar wind energy flux values. Pseudobreakups are associated with even lower energy fluxes than small substorms and appear typically for weakly positive IMF B-z. These results are in agreement with the scenario that pseudobreakups essentially are very weak substorms. Pseudobreakups appear during quiet times and during the growth phase or the recovery phase of weak or medium strong substorms. Time periods of enhanced geomagnetic activity with recurrent substorms are devoid of pseudobreakups. A detailed analysis of the different pseudobreakup types reveals that quiet time pseudobreakups appear predominantly during northward IMF. At least 20 percent of these appear at the poleward oval boundary. Optically, they do not differ much from very weak substorms. Growth phase pseudobreakups develop typically at the end of a 1 to 2 hour long excursion from northward to weakly southward IMF and are followed by quite weak substorms. A large majority of recovery phase pseudobreakups occur at a strongly polewardly displaced oval boundary at the end of a very active recovery phase. A considerable decrease of the polar cap size during the preceding substorm is connected to a northward turning of the IMF.

Place, publisher, year, edition, pages
2004. Vol. 109, no A12
Keyword [en]
pseudobreakup, substorm, solar wind, IMF, interplanetary magnetic-field, image-fuv imagers, magnetospheric substorm, auroral substorm, plasma sheet, geomagnetic disturbances, pseudo-breakup, growth-phase, onset, quiet
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:kth:diva-23979DOI: 10.1029/2004ja010488ISI: 000226028700003ScopusID: 2-s2.0-38949214394OAI: diva2:342678
QC 20100525 QC 20110928Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2011-09-28Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Kullen, AnitaKarlsson, Tomas
By organisation
Alfvén Laboratory
In the same journal
Journal of Geophysical Research
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 35 hits
ReferencesLink to record
Permanent link

Direct link