Fig. 12From: The ionospheric condition and GPS positioning performance during the 2013 tropical cyclone Usagi event in the Hong Kong regionVisibility and cycle slip of each GPS satellite derived from the HKPC station on 24 September 2013. The horizontal blue lines denote the visibility of the GPS satellites. The red triangles on the blue line are cycle slips. The scintillation period is from 12:00 to 18:00 UT represented with two vertical red dashed linesBack to article page