In this paper Pi2 pulsations at Zhongshan Station of Antarctica are analyzed from October 1 - 31, 1996. Their characteristics e. g. occurrence frequency,frequency, and polarization are studied. The characteristics of ...In this paper Pi2 pulsations at Zhongshan Station of Antarctica are analyzed from October 1 - 31, 1996. Their characteristics e. g. occurrence frequency,frequency, and polarization are studied. The characteristics of Pi2 pulsations are summerized as follows: (1 ) Pi2 pulsations at Zhongshan Station usually take place from 2000 MLT to 0200 MLT; the main frequencies are between 6. 79 mHz and 13. 58mHZ; (2 ) Pi2 pulsations with low frequencies are dominent. The range of main frequencies becomes narrow at midnight; (3) The Polarization of Pi2 pulsations are almost linear; (4) About the orientation of major axes the NW-SE direction is dominent before 2200 MLT and NE-SW is dominent after 2200 MLT. The generation mechanism of Pi2 pulsations at Zhongshan Station is discussed theoretically.展开更多
The solar wind almost disappeared on May 11,1999: the solar wind plasma density and dynamic pressure were less than 1cm^(-3) and 0.1 nPa respectively, while the interplanetary mag- netic field was northward. The polar...The solar wind almost disappeared on May 11,1999: the solar wind plasma density and dynamic pressure were less than 1cm^(-3) and 0.1 nPa respectively, while the interplanetary mag- netic field was northward. The polar ionospheric data observed by the multi-instruments at Zhong- shan Station in Antarctica on such special event day was compared with those of the control day (May 14). It was shown that geomagnetic activity was very quiet on May 11 at Zhongshan. The magnetic pulsation, which usually occurred at about magnetic noon, did not appear. The iono- sphere was steady and stratified, and the F_2 layer spread very little. The critical frequency of day- side F_2 layer, f_0F_2, was larger than that of control day, and the peak of f_0F_2 appeared 2 hours earlier. The ionospheric drift velocity was less than usual. There were intensive auroral E_s appearing at magnetic noon. All this indicates that the polar ionosphere was extremely quiet and geomagnetic field was much more dipolar on May 11. There were some signatures of auroral substorm before midnight, such as the negative deviation of the geomagnetic H component, accompanied with auroral E_s and weak Pc3 pulsation.展开更多
文摘In this paper Pi2 pulsations at Zhongshan Station of Antarctica are analyzed from October 1 - 31, 1996. Their characteristics e. g. occurrence frequency,frequency, and polarization are studied. The characteristics of Pi2 pulsations are summerized as follows: (1 ) Pi2 pulsations at Zhongshan Station usually take place from 2000 MLT to 0200 MLT; the main frequencies are between 6. 79 mHz and 13. 58mHZ; (2 ) Pi2 pulsations with low frequencies are dominent. The range of main frequencies becomes narrow at midnight; (3) The Polarization of Pi2 pulsations are almost linear; (4) About the orientation of major axes the NW-SE direction is dominent before 2200 MLT and NE-SW is dominent after 2200 MLT. The generation mechanism of Pi2 pulsations at Zhongshan Station is discussed theoretically.
基金the National Natural Science Foundation of China (Grant Nos. 40104009, 40074038)the Major Scientific Project of Chinese Academy of Sciences (655951-1-305)+1 种基金the National Social Commonweal Program (2001DIA50040-04) the Youth Foundation of the State Oceanic Administration of China (2000903).
文摘The solar wind almost disappeared on May 11,1999: the solar wind plasma density and dynamic pressure were less than 1cm^(-3) and 0.1 nPa respectively, while the interplanetary mag- netic field was northward. The polar ionospheric data observed by the multi-instruments at Zhong- shan Station in Antarctica on such special event day was compared with those of the control day (May 14). It was shown that geomagnetic activity was very quiet on May 11 at Zhongshan. The magnetic pulsation, which usually occurred at about magnetic noon, did not appear. The iono- sphere was steady and stratified, and the F_2 layer spread very little. The critical frequency of day- side F_2 layer, f_0F_2, was larger than that of control day, and the peak of f_0F_2 appeared 2 hours earlier. The ionospheric drift velocity was less than usual. There were intensive auroral E_s appearing at magnetic noon. All this indicates that the polar ionosphere was extremely quiet and geomagnetic field was much more dipolar on May 11. There were some signatures of auroral substorm before midnight, such as the negative deviation of the geomagnetic H component, accompanied with auroral E_s and weak Pc3 pulsation.
