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Zusammenfassung:
TEC values from a network of GPS/GNSS receivers operating in Greenland and North America and concurrent measurements from Antarctica are used to identify polar cap patches (PCP) and characterize their sizes, shapes, vector velocities, and occurrence rates. This investigation employs data for 2009 and 2010, years of minimum solar activity, and low TEC values to tune the processing algorithms during very low ionospheric densities. ACE’s observations of the IMF provide the solar wind context of the PCP measurements. The observations indicate that between 2009 and 2010, PCPs appeared almost immediately after the IMF Bz turned southward, but only when the solar wind velocity exceeded 290 km/s. An airglow all-sky imager at Qaanaaq in Greenland provides prompt verification of PCP activity and its characteristics. The patch velocity is determined using a cross-correlation analysis of the TEC data, indicating values between 600 and 1000 m/s. These values agree with the polar cap velocities measured with the imager and the SuperDARN radars. A trajectory analysis technique was used to step backward and forward the location of the TEC patch observations in time to search for the origin of the polar cap patches. The latest algorithm allows employing TEC measurements from different times to reconstruct the patch shape during transit across the polar cap.
