Blar i forfatter "Tanaka, Yoshimasa"

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    • Auroral molecular-emission effects on the atomic oxygen line at 777.4 nm 

      Oyama, Shin-Ichiro; Tsuda, Takuo T.; Hosokawa, Keisuke; Ogawa, Yasunobu; Miyoshi, Yoshizumi; Kurita, Satoshi; Kero, Antti; Fujii, Ryochi; Tanaka, Yoshimasa; Mizuno, Akira; Kawabata, Tetsuya; Gustavsson, Björn Johan; Leyser, Thomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-16)
      One of the representative auroral emission lines that radiates from F-region heights and is measurable on the ground is the 777.4 nm line from excited atomic oxygen. This line has been adopted, along with another E-region emission line, for example 427.8 nm, to estimate the mean energy and total energy flux of precipitating auroral electrons. The influence of emissions from part of the molecular ...

    • Eastward-expanding auroral surges observed in the post-midnight sector during a multiple-onset substorm 

      Tanaka, Yoshimasa; Ogawa, Yasunobu; Kadokura, Akira; Partamies, Noora; Whiter, Daniel; Enell, Carl-Fredrik; Brändström, Urban; Sergienko, Tima; Gustavsson, Björn Johan; Kozlovsky, Alexander; Miyaoka, Hiroshi; Yoshikawa, Akimasa (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-09)
      We present three eastward-expanding auroral surge (EEAS) events that were observed intermittently at intervals of about 15 min in the post-midnight sector (01:55–02:40 MLT) by all-sky imagers and magnetometers in northern Europe. It was deduced that each surge occurred just after each onset of a multiple-onset substorm, which was small-scale and did not clearly expand westward, because they were ...

    • Reconstruction of precipitating electrons and three-dimensional structure of a pulsating auroral patch from monochromatic auroral images obtained from multiple observation points 

      Fukizawa, Mizuki; Sakanoi, Takeshi; Tanaka, Yoshimasa; Ogawa, Yasunobu; Hosokawa, Keisuke; Gustavsson, Björn Johan; Kauristie, Kirsti; Kozlovsky, Alexander; Raita, Tero; Brändström, Urban; Sergienko, Tima (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-12)
      In recent years, aurora observation networks using high-sensitivity cameras have been developed in the polar regions. These networks allow dimmer auroras, such as pulsating auroras (PsAs), to be observed with a high signal-to-noise ratio. We reconstructed the horizontal distribution of precipitating electrons using computed tomography with monochromatic PsA images obtained from three observation ...