First GPS-TEC evidence for the wave structure excited by the solar terminator

Using TEC measurements from the global network of GPS receivers, we have obtained the first evidence for the wave structure excited by the solar terminator (ST), moving over the USA, Europe, and Japan. Two main types of the observed TEC disturbance were found: large-scale (LS) 60-min variations with an amplitude of about 0.5-1 TECU and medium-scale (MS) 15-min variations with an amplitude of about 0.05-0.1 TECU. The first type of disturbances was predicted in theoretical investigations and registered earlier using different methods of ionosphere radio sounding. The second type of the observed TEC disturbance is wave packets (WPs) generated when the time derivative of TEC is at its maximum. These WPs have duration of about 1-2 h and a time shift of about 1.5-2.5 h after the ST appearance at an attitude of 100 km. That ST-generated wave packets have been found for the first time. LS TEC disturbances and MS WPs are space-fixed along the ST line over a distance exceeding 1600 km.