[P-EM07] Space Weather, Space Climate, and VarSITI

[PEM07-36] Responses of polar cap ionosphere to successive CMEs in Dec 2014: 5 days continuous monitoring with two all-sky imagers

*Keisuke HOSOKAWA¹, Satoshi TAGUCHI², Kazuo SHIOKAWA³, Yasunobu OGAWA⁴, Yuichi OTSUKA³ (1.University of Electro-Communications, 2.Graduate School of Science, Kyoto University, 3.Solar-Terrestrial Environment Laboratory, Nagoya University, 4.National Institute of Polar Research)

Keywords:Polar cap, Polar cap patches, Polar cap aurora, Coronal Mass Ejection (CME)

In December 2014, three coronal mass ejections (CMEs) occurred successively during 4 days
interval from December 18 to 21. These CMEs arrived at the Earth respectively at December 21, 22
and 23 and caused a small magnetic storm (Dst ~-50 nT). During this interval, two all-sky airglow
imagers were operative in Longyearbyen, Norway (78.1N, 15.5E) and Resolute Bay, Canada (74.7N, 265.1E)
and monitoring the polar cap ionosphere continuously for 5 days from December 20 to 24. The two
all-sky imagers observed continuous generation/propagation of polar cap patches from the dayside
towards the nightside across the polar cap region during a prolonged interval of southward IMF Bz.
Such a continuous transportation of high-density plasma is visualized for the first time. At the
time of the arrival of second CME, the IMF Bz was directed strongly northward. During this period,
the polar cap shrank significantly, which implies that the magnetosphere was almost closed during
such a strongly northward IMF condition. By using the 5 days continuous optical data in the polar
cap region, we will discuss various responses of polar cap ionosphere to CME-induced solar wind
disturbances.