Local time distribution of reconnected field lines under northward interplanetary magnetic field conditions

Plasma observations in the northern cusp region are used to study the reconnection process and the inflow of plasma into the magnetosphere during intervals of northward interplanetary magnetic field. Several intervals are examined for which He++ of solar wind origin appears simultaneously with downgoing or counterstreaming O+ ions of ionospheric origin. The presence of both He++ and O+ suggests that magnetic reconnection on the magnetopause has occurred. The cases of downgoing or counterstreaming O+ observed in conjunction with He++ suggests that reconnection has occurred tailward of both cusps. The local time distribution of the occurrence of these events is investigated as a function of the state of the solar wind.