Southern Hemisphere poleward moving auroral forms

• Main Authors: E. E. Drury, S. B. Mende, H. U. Frey, J. H. Doolittle
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Hemisphere PMAFs is observed; consistent with Northern Hemisphere events. INDEX; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.550.9306; http://sprg.ssl.berkeley.edu/sprite/ago96/publication/2001JA007536.pdf

[1] This paper presents a statistical study of Southern Hemisphere poleward moving auroral forms (PMAFs) using optical data from the US Automatic Geophysical Observatory network in Antarctica. These Southern Hemisphere events are compared with Northern Hemisphere PMAFs, which have previously been observed during varied interplanetary magnetic field (IMF) configurations. The frequency of PMAF occurrence is studied as a function of IMF orientation and magnetic local time. Southern Hemisphere PMAFs are biased to Bz < 0 constituting 62 % of events, but are frequently observed during conditions of Bz> 0 constituting 38 % of events. Southern Hemisphere PMAFs share a similar IMF Bz dependence with Northern Hemisphere events [e.g., Fasel, 1995]. The primary modulator of PMAFs was found to be IMF By, which was negative for 81 % of events. Although the average background IMF was biased to By < 0, we find significant enhancement during By < 0 after this bias was removed. In a statistical study of Northern Hemisphere events, Fasel [1995] found 77 % of events occur during positive By. PMAFs appear to have an antisymmetric By dependence between hemispheres. We find By < 0 (By> 0) enhances the observation of PMAFs in the prenoon (postnoon) region, consistent with the release of magnetic stress. A morning bias of Southern