Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 35, 1015-1022, 2017
https://doi.org/10.5194/angeo-35-1015-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
29 Aug 2017
Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations
Sudong Xiao1, Tielong Zhang2,3, Guoqiang Wang2, Martin Volwerk3, Yasong Ge4, Daniel Schmid3, Rumi Nakamura3, Wolfgang Baumjohann3, and Ferdinand Plaschke3 1CAS Key Laboratory of Geospace Environment, University of Science and Technology of China, Hefei, China
2Harbin Institute of Technology, Shenzhen, China
3Space Research Institute, Austrian Academy of Sciences, Graz, Austria
4Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
Abstract. We investigate the occurrence rate of dipolarization fronts (DFs) in the plasma sheet by taking full advantage of all four Cluster satellites (C1–4) from years 2001 to 2009. In total, we select 466 joint-observation DF events, in which 318, 282, 254, and 236 DFs are observed by C1, C2, C3, and C4, respectively. Our findings are as follows: (1) the maximum occurrence rate is ∼ 15.3 events per day at X ∼ 15 RE in the XY plane, and the average occurrence rate is ∼ 5.4 events per day over the whole observation period; (2) the occurrence rate on the dusk side of the plasma sheet is larger and decreases with increasing BXYBLobe; (3) the occurrence rate within |Y|  <  6 RE increases gradually from X ≈ −19 to −15 RE and then decreases from X ≈ −15 to −10 RE; (4) the occurrence rate when AE > 200 nT is much larger than that when AE < 200 nT, indicating that DFs preferentially occur during high geomagnetic activity. The magnetic pileup and earthward and duskward ion flows could contribute to the increases in the occurrence rate from X ≈ −19 to −15 RE. We suggest that both geomagnetic activity and multiple DFs contribute to the high occurrence rate of the DFs. In addition, the finite length of the DF in the dawn–dusk direction can affect the chance that a satellite observes the DF.

Citation: Xiao, S., Zhang, T., Wang, G., Volwerk, M., Ge, Y., Schmid, D., Nakamura, R., Baumjohann, W., and Plaschke, F.: Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations, Ann. Geophys., 35, 1015-1022, https://doi.org/10.5194/angeo-35-1015-2017, 2017.
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