A statistical study of medium-scale ionospheric disturbances generated by solar terminator registered over Japan in 2008

A statistical study of wave packets of terminator origin using GEONET GPS data for 87 days in 2008 was done. There were some seasonal and latitudinal features in occurrence of the packets. In spring packets are registered 1.7 times more often in the south region than in the north one and in summer -1.3 times more often in the north than south region. Autumn packets registration rate have two maxima: 4 hour after and at the same time as terminator appears over the registration point. Similar distribution maxima are registered in summer in the south of Japan.