Large ionospheric disturbances during a minor geomagnetic storm on June 23, 2000

Annals of Geophysics

Barbara A Emery¹  Jianpeng Guo²  Zheng Li²  Fengsi Wei²  Xueshang Feng²  Xinhua Zhao² 

[1] High Altitude Observatory/NCAR, Boulder, CO,;SIGMA Weather Group, State Key Laboratory of Space Weather, CSSAR, Chinese Academy of Sciences, Beijing;

关键词: Ionospheric storm;    Minor geomagnetic disturbance;    Energy transfer;   

DOI  :  10.4401/ag-5409

来源: DOAJ

【 摘 要 】

We investigate the variations in the ionosphere during a small geomagnetic storm on June 23, 2000, using the total electron content of the Jet Propulsion Laboratory global positioning system, and the ionospheric critical frequency. Large and long-lasting reductions in the daytime electron density were observed at mid-latitudes in the northern hemisphere by ionosondes. These reductions reached 30% to 40% compared to the 27-day median value. At the same time, a transformation from similar large positive storm effects to negative storm effects was observed in the northern hemisphere by the global positioning system receivers. The geomagnetic disturbance was very weak from June 23-25, 2000, as the SYM-H index was >−40 nT and ASY-H was <90 nT. Of note, during this case there were neither long-lasting southward IMF Bz nor strong positive IMF By components, where a large positive IMF By might be the main reason for ionospheric storms during minor geomagnetic disturbances [Goncharenko et al. 2006]. We confirm a 13-h enhanced energy input from the disturbed solar wind by calculation of the Borovsky, Akasofu and Newell coupling functions, the global auroral precipitation, and the Joule heating. We suggest this enhanced energy input as the main cause of these intense ionospheric storms, although the maximum of the energy input was not large. In addition, we propose that the Newell coupling function might be more suitable for reflecting the energy transfer from the disturbed solar wind to the magnetosphere under weak geomagnetic activity.

【 授权许可】

Unknown