Blar i forfatter "Häggström, Ingemar"

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    • Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar 

      Viswanathan, Lakshmi Narayanan; Häggström, Ingemar; Mann, Ingrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-23)
      We present the results from investigation of spectra of polar mesospheric summer echoes (PMSE) observed with EISCAT VHF 224 MHz radar during energetic particle precipitation events in the summer of 2019. We used the sudden enhancements in electron densities derived from the VHF observations above 90 km as indicators of particle precipitation. We find that the altitude extent of the PMSE increased ...

    • Ion-dispersion and rapid electron fluctuations in the cusp : a case study 

      Buchert, Stephan C; Lunde, June; Ogawa, Yasunobu; Hirahara, Masafumi; Seki, Kanako; Ebihara, Yuusuke; Sakanoi, Takeshi; Asamura, Kazushi; Okada, Masaki; Raita, Tero; Häggström, Ingemar (Journal article; Tidsskriftartikkel; Peer reviewed, 2008)

    • 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 ...

    • Review of Environmental Monitoring by Means of Radio Waves in the Polar Regions: From Atmosphere to Geospace 

      Alfonsi, Lucilla; Bergeot, Nicolas; Cilliers, Pierre J.; De Franceschi, Giorgiana; Baddeley, Lisa; Correia, Emilia; Di Mauro, Domenico; Enell, Carl-Fredrik; Engebretson, Mark; Ghoddousi-Fard, Reza; Häggström, Ingemar; Ham, Young-bae; Heygster, Georg; Jee, Geonhwa; Kero, Antti; Kosch, Michael; Kwon, Hyuck-Jin; Lee, Changsup; Lotz, Stefan; Macotela, Liliana; Marcucci, Maria Federica; Miloch, Wojciech Jacek; Morton, Y. Jade; Naoi, Takahiro; Negusini, Monia; Partamies, Noora; Petkov, Boyan H.; Pottiaux, Eric; Prikryl, Paul; Shreedevi, P.R.; Slapak, Rikard; Spogli, Luca; Stephenson, Judy; Triana-Gómez, Arantxa M.; Troshichev, Oleg A.; Van Malderen, Roeland; Weygand, James M.; Zou, Shasha (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-23)
      The Antarctic and Arctic regions are Earth's open windows to outer space. They provide unique opportunities for investigating the troposphere–thermosphere–ionosphere–plasmasphere system at high latitudes, which is not as well understood as the mid- and low-latitude regions mainly due to the paucity of experimental observations. In addition, different neutral and ionised atmospheric layers at high ...

    • A Stimulated Emission Diagnostic Technique for Electron Temperature of the High Power Radio Wave Modified Ionosphere 

      Fu, Haiyang; Jiang, M. L.; Vierinen, Juha; Häggström, Ingemar; Rietveld, Michael T.; Varberg, Erik; Sato, Hiroatsu; Wu, Jiang; Scales, Wayne A.; Jin, Y. Q. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-09)
      We report observations of stimulated electromagnetic emission (SEE) induced by high power high frequency (HF) radio waves near the third electron gyroharmonic (3urn:x-wiley:00948276:media:grl64672:grl64672-math-0022) at European Incoherent Scatter Radar (EISCAT). It is discovered that stimulated Brillouin scattering (SBS) spectrum behaves similarly as spectral ion lines of the incoherent scatter ...

    • Systematic variation in observing altitude of enhanced ion line by the pump near fifth gyroharmonic 

      Wu, Jun; Rietveld, Michael T; Häggström, Ingemar; Zhao, H.; Xu, T; Xu, Z (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-20)
      The observation of ultra high frequency radar during an ionospheric experiment carrying out at the European Incoherent Scatter Scientific Association, demonstrates a systematic variation in the altitude of the pump enhanced ion line, which is quite remarkably dependent on the pump frequency, that is, when the pump frequency sweeps above the fifth gyroharmonic, the altitude of the enhanced ion line ...