Statistical analysis of upflowing ion beam and conic distributions at DE 1 altitudes

Abstract

Statistical analyses of energetic (0.01–17 keV) upflowing ions (UFI), beams, conies, and hybrid pitch angle distributions, have been made using the energetic ion composition spectrometer (EICS) data on the DE 1 satellite for the 8000‐km to 23,300‐km altitude range over a 5‐year period from September 1981 to June 1986. Hybrid types are defined here as combinations of lower‐energy beams and higher‐energy conics at three different energies (0.01–1, 1–4, and 4–17 keV). In general, it is found that (1) the source and transport mechanisms confine UFI mostly to auroral field lines; (2) although field‐aligned currents and UFI events have similar frequencies of occurrence, no obvious (one‐to‐one) relationship between current direction and UFI source characteristics was found; (3) although H+ and O+ UFI spatial (latitude, local time, and altitude) distributions are similar, O+ is more efficiently accelerated than H+ at higher values of Kp; and (4) the electric potential drop along auroral field lines, which would accelerate ions away from the ionosphere, is small (<1 kV) except perhaps in the dusk to midnight sectors where on occasion large values (1–10 kV) may be present.