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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 34, issue 1
Ann. Geophys., 34, 45–53, 2016
https://doi.org/10.5194/angeo-34-45-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 34, 45–53, 2016
https://doi.org/10.5194/angeo-34-45-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 18 Jan 2016

Regular paper | 18 Jan 2016

The geomagnetic cutoff rigidities at high latitudes for different solar wind and geomagnetic conditions

W. Chu1,2 and G. Qin1 W. Chu and G. Qin
  • 1State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
  • 2College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China

Abstract. Studying the access of the cosmic rays (CRs) into the magnetosphere is important to understand the coupling between the magnetosphere and the solar wind. In this paper we numerically studied CRs' magnetospheric access with vertical geomagnetic cutoff rigidities using the method proposed by Smart and Shea (1999). By the study of CRs' vertical geomagnetic cutoff rigidities at high latitudes we obtain the CRs' window (CRW) whose boundary is determined when the vertical geomagnetic cutoff rigidities drop to a value lower than a threshold value. Furthermore, we studied the area of CRWs and found out they are sensitive to different parameters, such as the z component of interplanetary magnetic field (IMF), the solar wind dynamic pressure, AE index, and Dst index. It was found that both the AE index and Dst index have a strong correlation with the area of CRWs during strong geomagnetic storms. However, during the medium storms, only AE index has a strong correlation with the area of CRWs, while Dst index has a much weaker correlation with the area of CRWs. This result on the CRW can be used for forecasting the variation of the cosmic rays during the geomagnetic storms.

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To study the coupling between the magnetosphere and the solar wind at high latitudes, the cosmic rays window (CRW) is defined. The area of the CRW is related to the solar wind-magnetospheric conditions, such as the z component of Interplanetary Magnetic Field, the solar wind dynamic pressure, AE index and Dst index. This result on the CRW may be used to help forecasting the variation of the cosmic rays during the geomagnetic storms.
To study the coupling between the magnetosphere and the solar wind at high latitudes, the cosmic...
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