ABSTRACT
We investigate the drivers of 40-150 keV hourly electron flux at geostationary orbit (GOES 13) using autoregressive moving average transfer functions (ARMAX) multiple regression models which remove the confounding effect of diurnal cyclicity and allow assessment of each parameter independently. By taking logs of the variables, we create nonlinear models. While many factors show high correlation with flux in single variable analysis (substorms, ULF waves, solar wind velocity (V), pressure (P), number density (N) and electric field (E y ), IMF Bz, Kp, and SymH), ARMAX models show substorms are the dominant influence at 40-75 keV and over 20-12 MLT, with little difference seen between disturbed and quiet periods. The Ey influence is positive post-midnight, negative post-noon. Pressure shows a negative influence, strongest at 150 keV. ULF waves are a more modest influence than suggested by single variable correlation. Kp and SymH show little effect when other variables are included. Using path analysis, we calculate the summed direct and indirect influences through the driving of intermediate parameters. Pressure shows a summed direct and indirect influence nearly half that of the direct substorm effect. N, V, and B z , as indirect drivers, are equally influential. While simple correlation or neural networks can be used for flux prediction, neither can effectively identify drivers. Instead, consideration of physical influences, removing cycles that artificially inflate correlations, and controlling the effects of other parameters gives a clearer picture of which are most influential in this system.
ABSTRACT
Approaches regarding how to turn the instrument background counts into scientifically valuable data are presented in this Technical Report on Methods. The background counts due to penetrating energetic particles of radiation belts detected on Cluster CIS HIA and CODIF instruments and the Double Star HIA instrument are used in these approaches. In HIA spectrograms, the background counts are seen simultaneously in all energy channels marking the entry and exit of the radiation belts by the spacecraft, therefore, the locations of the boundaries of the outer and inner belts can be determined. In the case when HIA measurements are not readily available, a new method is proposed in which supplementary data streams within the CODIF telemetry is exploited. It employs separate counts that register "start," "stop," and "non-valid" signals increasing in the presence of penetrating particles even when no corresponding increase are shown in the energy-time spectrograms. The locations of the radiation belt boundaries are defined by following the changes in counts gradients with time and visual inspection of all the available measurements. The July-August 2007 and September-October 2012 time periods are analyzed for method demonstration on a presence of a third radiation belt, or storage ring.
ABSTRACT
Low O+/H+ ratio produced stronger ring currentInclusion of physics-based ionospheric outflow leads to a reduction in the CPCPOxygen presence is linked to a nightside reconnection point closer to the Earth.
