PROGRAM: P-19

Title:

Abstract:

Geomagnetic crochet is believed to be directly related to solar flares. Relevant studies are important to understand the influence of solar eruptions on near-earth space environment, and to develop space weather forecasting techniques. In this paper, using the data from the geomagnetic station of Shandong University (Wei Hai), the Intermagnet Geomagnetic chain and the Meridian Space Weather Monitoring Project, the GOES satellite and the digital ionosonde system, we investigate a geomagnetic crochet associated with a M5.6 solar flare. Our conclusions are listed as follows. The characteristics of geomagnetic crochet were different between the northern and southern hemispheres and prenoon/postnoon, and the geomagnetic response had about 3 minutes' delay in comparison to the peak time of the solar flare. Geomagnetic disturbance was not obvious at night. We used the data of more than 50 magnetic stations located in the dayside hemisphere and found that the amplitude of geomagnetic crochet had a normal distribution, with the maximum being near noon. At last, we used geomagnetic data to get the crochet current system S_s during the event and the quiet current system S_q during quiet days. Our statistical study on the geomagnetic crochets and solar flares from 1996 to 2015 shows that the X-class flare is most likely the cause of magnetic crochets, and the possibility is about 42%.; most magnetic crochets are caused by M-class flares; smaller flares, like A-, B-, C-class flares are hardly associated with magnetic crochets.

Acknowledgements:

This work was supported by the National Natural Science Foundation of China (Grant nos. 41604139, and 41574138). We acknowledge the Intermagnet Geomagnetic chain, the Meridian Space Weather Monitoring Project and the geomagnetic station in Weihai of Shandong University for making available the geomagnetic data. We also acknowledge the the GOES satellites and the digital ionosonde system at I-Chen station for providing the data.

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