THE IONOSPHERIC POLAR WIND OBSERVATIONS WITH EISCAT VHF RADAR
Wu JIAN(China Research Institute of Radioware Propagation, P. O. Box 138, Xinxiang 453003)MICHEL BLANC(OMP, 14 Avenue Edouard Belin, 31400 Toulouse,France)DENIS ALCAYDE(CESR, 9 Avenue Colonel-Roche, 31029 Toulouse, Prance)
The polar wind was suggested theoretically more than 20 years before. Sufficient evidence has not been given by observations, especially observations in the high-latitude ionosphere. In this paper, we report the results of the first H+ polar wind observations with EISCAT VHF radar. It is shown during the observations that the H+ ion velocity is always upwards in the topside ionosphere and increases with altitude in the observed range, which implys that there is a pe-rament H+ thermal escape in the topside ionosphere with a temperature less than 0.26 eV, say the polar wind. Its outflow velocity is about 1 km/s at 1000 km altitude, and the flux arrives at about 1012 m-2.s-1 approaching the satured flux. The flow is still in the subsonic regime in the observed altitude range.