Blar i forfatter "Ivchenko, Nickolay"

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    • Auroral ion acoustic wave enhancement observed with a radar interferometer system 

      Schlatter, Nicola M.; Belyey, Vasyl; Gustavsson, Björn Johan; Ivchenko, Nickolay; Whiter, Daniel; Dahlgren, Hanna; Tuttle, Sam; Grydeland, Tom (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-20)
      Measurements of naturally enhanced ion acoustic line (NEIAL) echoes obtained with a five-antenna interferometric imaging radar system are presented. The observations were conducted with the European Incoherent SCATter (EISCAT) radar on Svalbard and the EISCAT Aperture Synthesis Imaging receivers (EASI) installed at the radar site. Four baselines of the interferometer are used in the analysis. Based ...

    • Enhanced EISCAT UHF backscatter during high-energy auroral electron precipitation 

      Schlatter, Nicola M.; Ivchenko, Nickolay; Sergienko, T; Gustavsson, Björn Johan; Brändström, B. U. E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Natural enhancements in the backscattered power of incoherent scatter radars up to 5 orders of magnitudes above the thermal backscatter are sometimes observed at high latitudes. Recently observations of enhancements in the backscattered power including a feature at zero Doppler shift have been reported. These enhancements are limited in altitude to tens of kilometers. The zero Doppler shift ...

    • Horizontal electric fields from flow of auroral O+(2P) ions at sub-second temporal resolution 

      Tuttle, Sam; Lanchester, Betty; Gustavsson, Björn Johan; Keith Whiter, Daniel; Ivchenko, Nickolay; Fear, R. C.; Lester, Mark (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-14)
      Electric fields are a ubiquitous feature of the ionosphere and are intimately linked with aurora through particle precipitation and field-aligned currents. They exhibit order-of-magnitude changes on temporal and spatial scales of seconds and kilometres respectively which are not easy to measure; knowing their true magnitude and temporal variability is important for a theoretical understanding of ...

    • Observations of HF-induced instability in the auroral E region 

      Schlatter, Nicola M.; Ivchenko, Nickolay; Gustavsson, Björn Johan; Leyser, Thomas; Rietveld, Michael T (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Enhancements were observed in backscattered radar power during an ionospheric heating experiment from two distinct altitude regions in the auroral E region above Tromsø. For the experiment the EISCAT Tromsø heater was operated with O mode and X mode alternated at 4.04 MHz, close to the 3rd electron gyroharmonic. Ion-line data recorded with the EISCAT UHF radar reveal different temporal ...

    • Patch Size Evolution During Pulsating Aurora 

      Partamies, Noora; Bolmgren, Karl; Heino, Erkka; Ivchenko, Nickolay; Borovsky, Joseph E.; Sundberg, Hanna (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-30)
      We report both decreasing and increasing trends in the patch sizes during pulsating aurora events. About 150 pulsating auroral events over the Fennoscandian Lapland have been successfully analyzed for their average patch size, total patch area, and number of patches as a function of event time, typically 1–2 hr. An automatic routine has been developed to detect patches in the all‐sky camera images. ...

    • Plasma-neutral gas interactions in various space environments: Assessment beyond simplified approximations as a Voyage 2050 theme 

      Yamauchi, Masatoshi; De Keyser, Johan; Parks, George; Oyama, Shin-ichiro; Wurz, Peter; Abe, Takumi; Beth, Arnaud; Daglis, Ioannis A.; Dandouras, Iannis; Dunlop, Malcolm; Henri, Pierre; Ivchenko, Nickolay; Kallio, Esa; Kucharek, Harald; Liu, Yong C.-M.; Mann, Ingrid; Marghitu, Octav; Nicolaou, Georgios; Rong, Zhaojin; Sakanoi, Takeshi; Saur, Joachim; Shimoyama, Manabu; Taguchi, Satoshi; Tian, Feng; Tsuda, Takuo; Tsurutani, Bruce; Turner, Drew; Ulich, Thomas; Yau, Andrew; Yoshikawa, Ichiro (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-26)
      In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task ...