Timing and localization of ionospheric signatures associated with substorm expansion phase onset Export

@article{citeulike:4637334, abstract = {In this paper, we present case studies of the optical and magnetic signatures of the characteristics of the first minute of substorm expansion phase onset observed in the ionosphere. We find that for two isolated substorms, the onset of magnetic pulsations in the 24–96 s period wavelet band are colocated in time and space with the formation and development of small-scale optical undulations along the most equatorward preexisting auroral arc prior to auroral breakup. These undulations undergo an inverse spatial cascade into vortices prior to the release of the westward traveling surge. We also present a case study of a multiple activation substorm, whereby discrete onsets of ULF wave power above a predetermined quiet time threshold are shown to be associated with specific optical intensifications and brightenings. Moreover, in the multiple activation substorm event, we show that neither the formation of the small-scale undulations nor the formation of similar structures along a north–south aligned arc is sufficient to produce auroral breakup associated with expansion phase onset. It is only ∼10 min after these two disparate activation regions initiate that auroral breakup and the subsequent formation of a westward traveling surge occur. We discuss the implications of these results in terms of the triggering mechanisms likely to be occurring during these specific events. }, author = {Rae, Jonathan I. and Mann, Ian R. and Murphy, Kyle R. and Milling, David K. and Parent, Adrienne and Angelopoulos, Vassilis and Frey, Harald U. and Kale, Andy and Watt, Clare E. J. and Mende, Stephen B. and Russell, Christopher T.}, citeulike-article-id = {4637334}, citeulike-linkout-0 = {http://www.agu.org/pubs/crossref/2009/2008JA013559.shtml}, citeulike-linkout-1 = {http://dx.doi.org/10.1029/2008JA013559}, day = {22}, doi = {10.1029/2008JA013559}, issn = {0148-0227}, journal = {Journal of Geophysical Research - Space Physics}, month = {January}, number = {null}, pages = {A00C09+}, posted-at = {2009-05-26 21:44:37}, priority = {2}, title = {Timing and localization of ionospheric signatures associated with substorm expansion phase onset}, url = {http://dx.doi.org/10.1029/2008JA013559}, volume = {114}, year = {2009} }

TY - JOUR ID - citeulike:4637334 L3 - citeulike-article-id:4637334 N2 - In this paper, we present case studies of the optical and magnetic signatures of the characteristics of the first minute of substorm expansion phase onset observed in the ionosphere. We find that for two isolated substorms, the onset of magnetic pulsations in the 24–96 s period wavelet band are colocated in time and space with the formation and development of small-scale optical undulations along the most equatorward preexisting auroral arc prior to auroral breakup. These undulations undergo an inverse spatial cascade into vortices prior to the release of the westward traveling surge. We also present a case study of a multiple activation substorm, whereby discrete onsets of ULF wave power above a predetermined quiet time threshold are shown to be associated with specific optical intensifications and brightenings. Moreover, in the multiple activation substorm event, we show that neither the formation of the small-scale undulations nor the formation of similar structures along a north–south aligned arc is sufficient to produce auroral breakup associated with expansion phase onset. It is only ∼10 min after these two disparate activation regions initiate that auroral breakup and the subsequent formation of a westward traveling surge occur. We discuss the implications of these results in terms of the triggering mechanisms likely to be occurring during these specific events. IS - null JF - Journal of Geophysical Research - Space Physics SN - 0148-0227 TI - Timing and localization of ionospheric signatures associated with substorm expansion phase onset VL - 114 SP - A00C09 AU - Rae, Jonathan AU - Mann, Ian AU - Murphy, Kyle AU - Milling, David AU - Parent, Adrienne AU - Angelopoulos, Vassilis AU - Frey, Harald AU - Kale, Andy AU - Watt, Clare AU - Mende, Stephen AU - Russell, Christopher PY - 2009/01/22/ UR - http://dx.doi.org/10.1029/2008JA013559 ER -