Wind observation of gyrating-like ion distributions and low frequency waves upstream from the Earth's bow shock

K. Meziane, C. Mazelle, C. d'Uston, H. Reme, R. P. Lin, C. W. Carlson, D. Larson, J. P. McFadden, R. E. Ergun, K. A. Anderson, G. K. Parks, D. Berdichevsky, and R. P. Lepping

Centre d'Etude Spatiale des Rayonnements, 9 Avenue du Colonel Roche, 31400 Toulouse


Several upstream ion distributions having a gyrating signature have been identified with the 3DP/PESA-High analyzer on board the WIND spacecraft. These distributions are observed at distances greater than 20 RE from the Earth's bow shock. The distributions are observed in association with low frequency waves propagating quasi-parallel to the background magnetic field. By estimating the bulk velocity of the gyrating ions, we have found that the waves resonate with the particles. The observation of grating ions at large distances from the shock suggests their local production, probably from field-aligned beam disruption.

Adv. Space Res., 20, No. 5, 703-706, 1997