When plasma streams tie up equatorial plasma irregularities with auroral ones

Under disturbed conditions, they appear at North America low latitudes as a part of extended postsunset equatorial plasma bubbles, and further, they are streaming from low latitudes in a northwestward, poleward direction toward the main ionospheric trough and auroral irregularities zone.

The poleward-streaming plasma depletions represent a new phenomenon with the similar northwestward transportation path across the continental United States as storm-enhanced density (SED) plumes. The channels of poleward-streaming plasma depletions were stretched from low-latitude base toward higher latitudes-they are found to occur for geomagnetic storms under specific combination of steady southward interplanetary magnetic field, subauroral polarization streams (SAPS) electric fields, and enhanced westward drifts at midlatitudes, resulting in northwestward plasma transportation equatorward of the SAPS region.