Blar i forfatter "Tjulin, Anders"

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    • High-latitude crochet: Solar-flare-induced magnetic disturbance independent from low-latitude crochet 

      Yamauchi, Masatoshi; Johnsen, Magnar Gullikstad; Enell, Carl-Fredrik; Tjulin, Anders; Willer, Anna; Sormakov, Dmitry A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-03)
      A solar-flare-induced, high-latitude (peak at 70–75<sup>∘</sup> geographic latitude – GGlat) ionospheric current system was studied. Right after the X9.3 flare on 6 September 2017, magnetic stations at 68–77<sup>∘</sup> GGlat near local noon detected northward geomagnetic deviations (ΔB) for more than 3 h, with peak amplitudes of >200 nT without any accompanying substorm activities. From its location, ...

    • Inferring neutral winds in the ionospheric transition region from atmospheric-gravity-wave traveling-ionospheric-disturbance (AGW-TID) observations with the EISCAT VHF radar and the Nordic Meteor Radar Cluster 

      Günzkofer, Florian; Pokhotelov, Dimitry; Stober, Gunter; Mann, Ingrid Brigitte; Vadas, Sharon L.; Becker, Erich; Tjulin, Anders; Kozlovsky, Alexander; Tsutsumi, Masaki; Gulbrandsen, Njål; Nozawa, Satonori; Lester, Mark; Belova, Evgenia; Kero, Johan; Mitchell, Nicholas J.; Borries, Claudia (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-18)
      Atmospheric gravity waves and traveling ionospheric disturbances can be observed in the neutral atmosphere and the ionosphere at a wide range of spatial and temporal scales. Especially at medium scales, these oscillations are often not resolved in general circulation models and are parameterized. We show that ionospheric disturbances forced by upward-propagating atmospheric gravity waves can be ...

    • Radar studies of ionospheric dusty plasma phenomena 

      Mann, Ingrid; Gunnarsdottir, Tinna; Häggström, Ingemar; Eren, Saliha; Tjulin, Anders; Myrvang, Margaretha; Rietveld, Mike T; Dalin, Peter; Jozwicki, Dorota; Trollvik, Henriette Marie Tveitnes (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-17)
      We discuss the influence of charged dust on radar observations in the Earth ionosphere. This region in the upper Earth atmosphere can be described as a partially ionized, low‐temperature plasma. Plasma parameters vary by orders of magnitude spatially and in time. Dust particles influence the charge balance, in some cases dusty plasma condition is met. The polar mesospheric echoes are an example of ...