Blar i forfatter "Sergiengko, Timothy"

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    • EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity of Polar Mesospheric Summer Echoes Associated With a Geomagnetic Disturbance 

      Lee, Young-Sook; Kim, Young Ha; Kim, Kyung-Chan; Kwak, Young-Sil; Sergiengko, Timothy; Kirkwood, Sheila; Johnsen, Magnar Gullikstad (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-04)
      By analyzing a data set from the European Incoherent SCATter (EISCAT) Very High Frequency (VHF) radar at Tromsø, we find that both radar reflectivity and upward ion velocity in a polar mesospheric summer echo (PMSE) layer simultaneously increased at the commencement of a local geomagnetic disturbance, which occurred at midnight on 9 July 2013. The onset of the upward velocity was followed by periodic ...

    • Ionospheric Response Observed by EISCAT During the 6–8 September 2017 Space Weather Event: Overview 

      Yamauchi, M; Sergiengko, Timothy; Enell, Carl-Fredrik; Schillings, A.; Slapak, R.; Johnsen, Magnar Gullikstad; Tjulin, A.; Nilsson, H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-03)
      We present ionospheric plasma conditions observed by the EISCAT radars in Tromsø and on Svalbard, covering 68°–81° geomagnetic latitude, during 6–8 September 2017. This is a period when X2.2 and X9.3 X‐ray flares occurred, two interplanetary coronal mass ejections (ICMEs) arrived at the Earth accompanied by enhancements of MeV‐range energetic particle flux in both the solar wind (SEP event) and inner ...