Latitudinal Variation of Polar Wind Profiles from Alouette-II Data

165-167The electron density profiles obtained by Alouette-II satellite have been used to study the polar wind velocities at the high latitudes. It has been shown that the most favourable conditions for H+ to attain supersonic speeds are a lower plasma temperature at a reference level of 1000 km and a higher temperature gradient above that level. Further studies on the variation of polar wind velocities with geomagnetic latitude in the range 50-65° have yielded some very significant results. One such observation has been the significance of O+ -H+ transition level on the latitudinal variation of H+ velocities. The results clearly indicate that below the O+-H+ transition level the increasing trend in H+ velocities with latitude is very distinct while the H+ velocities do not exhibit any significant variation with latitude above the transition level. This is in agreement with the currently known processes affecting the H+ ion flow at high latitudes