Polar Ionospheric Large‐Scale Structures and Dynamics Revealed by TEC Keogram Extracted From TEC Maps

Abstract

AbstractA method named total electron content (TEC) keogram is introduced for surveying the large‐scale irregularities continuously in the polar ionosphere. The TEC keogram is developed from a movie of TEC maps along various meridian lines from the dayside to the nightside across the magnetic pole, trying to identify and track several types of ionospheric structures. Through two examples, a clear train of polar cap patches are identified from TEC keogram and confirmed by SuperDARN radar observations. The motion speed of these patches estimated from this tool agrees with SuperDARN radar measurements. Then, the motions of patches relative to the background convection through the whole polar cap are statistically studied for the first time. Moreover, the occurrence dependence of fully tracked patches on months, UT hours, and interplanetary magnetic field conditions is generally consistent with previous reports. These results suggest that the TEC keogram offers a power tool for continuous monitoring and studying of large‐scale plasma irregularities in the polar ionosphere.