Rocket Data on Birkeland Currents

Sounding rocket data on Birkeland currents will be reviewed. Both satellite and rocket data indicate that current sheets are associated with auroral displays and that the electrons responsible for the production of auroral forms carry a significant fraction of the conventional current directed out of the atmosphere necessary to produce local magnetic effects. Although experimental data cannot yet define the overall magnetospheric pattern of the Birkeland current system, there are a few measurements which indicate that the return current might be carried by low energy electrons (less than a few hundred eV) streaming out of the atmosphere. Recent data on the observations of field-aligned auroral electron fluxes and monoenergetic peaks in the electron spectrum will also be discussed. Multiple monoenergetic peaks in electron spectra have been observed in three of our rocket flights. One of the peaks is isotropic in pitch angle whereas the other is observed to be sharply field-aligned. The field-aligned fluxes were measured near the northern and southern borders of the auroral luminosity and over a bright curl