Key;
Laboratory;
for;
Polar;
Science,;
Polar;
Research;
Institute;
of;
China,;
Shanghai;
200136,;
China;
Laboratory;
of;
Ionospheric;
Environment,;
Institute;
of;
Geology;
and;
Geophysics,;
Chinese;
Academy;
of;
Sciences,;
Beijing;
100029,;
China;