Ionospheric convection signatures observed by De 2 during northward interplanetary magnetic field

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Abstract
Observations of the ionospheric convection signature at high latitudes are examined during periods of prolonged northward interplanetary magnetic field (IMF). The data from Dynamics Explorer 2 show that a four‐cell convection pattern can frequently be observed in a region that is displaced to the sunward side of the dawn‐dusk meridian regardless of season. In the eclipsed ionosphere, extremely structured or turbulent flow exists with no identifiable connection to a more coherent pattern that may simultaneously exist in the dayside region. The two highest‐latitude convection cells that form part of the coherent dayside pattern show a dependence on the y component of the IMF. This dependence is such that a clockwise circulating cell displaced toward dawn dominates the high‐latitude region when By is positive. Anticlockwise circulation displaced toward dusk dominates the highest latitudes when By is negative. Examination of the simultaneously observed energetic particle environment suggests that both open and closed field lines may be associated with the high‐latitude convection cells. On occasions these entire cells can exist on open field lines. The existence of closed field lines in regions of sunward flow is also apparent in the data.