Super Dual Auroral Radar Network observations of convection during a period of small-magnitude northward IMF

Observations of the high-latitude northern hemisphere convection pattern are presented for varying small-magnitude interplanetary magnetic field (IMF) conditions. A new data analysis technique is used which makes use of all available data from the SuperDARN network rather than only using data from the regions of overlap of radar fields of view. Using this technique, the area over which convection is determined is often greatly extended from the region of overlap. The IMF during this period was small magnitude, |B| < 4 nT. During one interval, IMF B_z was northward, while B_y. was nearly zero. Convection during this interval evolved to a pattern with a large dusk cell with flow across the noon meridian from dusk toward dawn. In a later interval, IMF B_z and B_y were both nearly zero. During this interval, convection evolved to a four-cell pattern. Comparison of the observations with conceptual models showed significant differences for both intervals. During the first interval, statistical models and the observations compared favorably. During the second interval, however, the observations showed a significantly different pattern from the first interval, while statistical models predict the same pattern for both intervals. The behavior of the convection pattern can be in part ascribed to the role played by B_x, which was the dominant IMF component throughout this interval.