GPS total electron content variations associated with a polar cap arc

Abstract

We report an example of total electron content (TEC) variations, using Global Positioning System (GPS) measurements, associated with a polar cap arc detected by an all‐sky imager and ionosonde at a polar cap station. During the transit of the arc, GPS signals along the arc length showed an increase of ∼2 TEC units whereas GPS signals perpendicular to the arc showed only an increase of ∼0.3 TEC units. This indicates that the GPS TEC variations associated with a polar cap arc are dependent on the geometry of the GPS raypaths with respect to the arc. Ionosonde measurements confirm that this arc was an E region feature at ∼110 km with peak electron density of 5.4 × 10 11 el/m 3 . Estimated speed of the arc using a GPS triangulation method was about 300 m/s.