In the paper the high latitude ionospheric absorption events, monitored by an imaging riometer at Zhongshan Station, Antarctica, are examined during magnetic storms in early May, 1998. The storm absorption at ~0 639 UT on May 2 was mainly an equatorward progressing absorption event, which were associated with a strong negative bay of the magnetic H component and with a large Pc3 range pulsation. There was a time lag of about 1. 5 hours between the onset of the ionospheric disturbance and the IMF southward turning in the solar wind. The event at 2 222 UT on May 2 was a typical midnight absorption spike event. The absorption region took the form of an elongated strip with the length of 100-150 km and the width of 30-40 km. The absorption during 0 830-1 200 UT on May 6 was a polar cap absorption (PCA) event, caused by intense precipitation of high-energy protons erupted after a large solar flare explosion.
Ionospheric absorption at Zhongshan Station, Antarctica during magnetic storms in early May, 1998
1 Akasofu S-I (1981) : Energy coupling between the solar wind and magnetosphere. Space Set. Rev., 28:121 -142.
2 Baker DN, Allen JH. Kanekal SG. Reeves GD (1998) : Disturbed space enviroment may have been related to pager satellite failure. EOS Trans., AGUt 79 (40) : 477-483.
3 Detrick DL, Rosenberg TJ (1990) : A phase-array radiowave imager for studies of cosmic noise absorption. Radio Sci., 25:325-338 DOI:10.1029/RS025i004p00325
4 Hargreaves JK, Chivers HJA. Nielson E (1979) : Properties of spike events in auroral absorption. J, Geophys. Res., 84:4245-4250. DOI:10.1029/JA084iA08p04245
5 Huang CYt Burke WJ, Gussenhovcn MS, Hardy DA, Gentile LC (1998) : Ionospheric response to magnetic forcing: magnetic cloud passage of October 18-20, 1995. Geophys. Res. Lett.. 25 (14) :2581-2584.
6 Little CG, Leinbach H (1958) : Some measurements of high-latitude ionospheric absorption using extraterrestrial radio waves. Proc. IRE, 46:334-348. DOI:10.1109/JRPROC.1958.286795
7 Liu YH, Liu RY, He LS, Hu HQ, Nishino M, Sano M, Yamagishi H, Sato N (1999) : Preliminary result of imaging riometer at Zhongshan Station, Antarctica. Chinese Journal of Polar Science. 10 (1) : 33-40.
8 Nielson Et Axford WI (1977) : Small scale auroral absorption events asscxriated with substorms. Nature, 267: 502-504. DOI:10.1038/267502a0
9 Nishino M, Yamagishi H. Sato N. Sano Y, Liu RY, Hu HQ, Stauning P (1998) : Initialresults of imaging riometer observations at polar cap conjugate stations. Proc. NIPR Symp. Upper Atmos. Phys., 12: 58 -72.
10 Stauning P (1996〉: Investigation of ionospheric radio wave absorption processes using imaging riometer techniques. J. Atmos. Terr. Phys. f 58 (6); 753-764. DOI:10.1016/0021-9169(95)00072-0
11 Stauning P (1998) : Substorm modeling based on observations of an intense high-latitude absorption surge event. J. Geophys. Res., 103 (A11) : 26433-26452. DOI:10.1029/97JA03596
12 Stauning P. Rosenberg TJ (1996) : High-latitude daytime absorption spike events. J. Geophys. Res., 101 (A2) : 2377-2396. DOI:10.1029/95JA03125