posted on 2015-04-29, 14:00authored byM-T. Walach, Stephen A. Milan
Magnetospheric modes, including substorms, sawtooth events, and steady magnetospheric convection events, have in the past been described as different responses of the magnetosphere to coupling with the solar wind. Using previously determined event lists for sawtooth events, steady magnetospheric convection events, and substorms, we produce a statistical study of these event types to examine their similarities and behavior in terms of solar wind parameters, auroral brightness, open magnetospheric flux, and geomagnetic indices. A superposed epoch analysis shows that individual sawteeth show the same signatures as substorms but occur during more extreme cases of solar wind driving as well as geomagnetic activity. We also explore the limitations of current methods of identifying steady magnetospheric convection events and explain why some of those events are flagged inappropriately. We show that 58% of the steady magnetospheric convection events considered, as identified by criteria defined in previous studies are part of a prolonged version of substorms due to continued dayside driving during expansion phase. The remaining 42% are episodes of enhanced magnetospheric convection, occurring after extended periods of dayside driving.
Funding
The IMAGE processing was supported by the European Union Framework 7 Programme, ECLAT Project grant 263325. M.-T.W. was supported by a studentship from the Science and Technology Facilities Council, UK. S.E.M. was supported on the STFC grant ST/K001000/1.
History
Citation
Journal of Geophysical Research: Space Physics, 120, 1751–1758
Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy
The OMNI data used in this study are available on the GSFC/SPDF OMNIWeb
platform, which can be found at http://cdaweb.gsfc.nasa.gov/. The original IMAGE data are available through
the IMAGE FUV homepage (http://sprg.ssl.berkeley.edu/image/), and the analyzed IMAGE data set is available from the Cluster Science Archive (http://www.cosmos.esa.int/web/csa/).
The event lists and code used to generate the plots in this paper are stored on University of Leicester computers and are available on request.