Observations of significant magnetosheath antisolar energy flow

Evidence for significant but sporadic magnetosheath energy flows in the antisolar direction is presented, using observations of 50 to 220-keV ions made by the NOAA/Applied Physics Laboratory energetic particle experiment on the Imp 7 satellite. The observations have been made in the dawn and dusk magnetosheath at distances of approx.35R/sub E/ from the earth and cover a wide range of Z/sub S/M. Direct observations of 50-to 220-keV ions yield an energy flow for the case studied of 2(10)3-2(10)2 erg/cm2 s. By using a somewhat arbitrary but reasonable magnetosheath area based on 1 year of synoptic survey of such flows a total magnetosheath > or =50-keV ion energy flow of > or approx. =1018 ergs/s is obtained. Reasonable spectral extrapolations yield somewhat larger total flows. These values indicate that ions carry at least an equal portion of the energetic particle magnetosheath energy flow as the extrapolated >1-keV electron flow obtained by Baker and Stone (1977). Possible sources of this energy flow include dissipation processes due to a magnetopause electric field, leakage of magnetospheric particles through the magnetopause into the magnetosheath, bow shock acceleration, and magnetosheath acceleration