Blar i forfatter "Häggström, I."

Viser treff 1-6 av 6

    • The behavior of electron density and temperature during ionospheric heating near the fifth electron gyrofrequency 

      Wu, Jun; Wu, Jian; Rietveld, Michael T.; Häggström, I.; Zhao, Haisheng; Xu, Zhengwen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-27)
      The experimental phenomena involving the changes in electron temperature and electron density as a function of pump frequency during an ionospheric heating campaign at European Incoherent Scatter near Tromsø, Norway, are reported. When the pump frequency is slightly above the fifth electron gyrofrequency, the UHF radar observation shows some apparent enhancements over a wide altitude range in radar ...

    • Electron Temperature Inversion by Stimulated Brillouin Scattering During Electron Gyroharmonic Heating at EISCAT 

      Fu, H. Y.; Jiang, M. L.; Wang, K. N.; Wu, J.; Li, Q.L.; Rietveld, Michael T; Varberg, E.; Häggström, I.; Jin, Y.-Q. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-25)
      This work reports a holistic experimental investigation of stimulated Brillouin scattering (SBS) features and electron temperature inversion near the third electron gyroharmonic 3<i>f</i><sub>ce</sub> using the European Incoherent Scatter (EISCAT) heating facility. The evolution of SBS features including spectral offset, width, and power varies asymmetrically near 3<i>f</i><sub>ce</sub>. The asymmetries ...

    • The Extending of Observing Altitudes of Plasma and Ion Lines During Ionospheric Heating 

      Wu, Jun; Wu, Jian; Rietveld, Michael T; Häggström, I.; Xu, Zhengwen; Zhao, Haisheng (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-26)
      The ultrahigh-frequency observation during an ionospheric heating experiment on 11 March 2014 at the European Incoherent Scatter Scientific Association Tromsø site illustrated a remarkable extension of observing altitudes of the enhanced plasma line and the ion line, implying that the enhanced ion acoustic wave and Langmuir wave should satisfy the Bragg condition within the extending altitude range. ...

    • First wind shear observation in PMSE with the tristatic EISCAT VHF radar 

      Mann, Ingrid; Häggström, I.; Tjulin, A; Rostami, S; Anyairo, CC; Dalin, P (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-05)
      The Polar Summer Mesosphere has the lowest temperatures that occur in the entire Earth system. Water ice particles below the optically observable size range participate there in the formation of strong radar echoes (Polar Mesospheric Summer Echoes, PMSE). To study PMSE we carried out observations with the European Incoherent Scatter (EISCAT) VHF and EISCAT UHF radar simultaneously from a site near ...

    • Infrasound - the cause of strong Polar Mesosphere Winter Echoes? 

      Rietveld, Michael T.; Kirkwood, S.; Chilson, P.; Belova, E.; Häggström, I.; Singer, W.; Dalin, P. (Journal article; Peer reviewed; Tidsskriftartikkel, 2006-03-23)
      The ESRAD 52-MHz and the EISCAT 224-MHz radars in northern Scandinavia observed thin layers of strongly enhanced radar echoes from the mesosphere (Polar Mesosphere Winter Echoes - PMWE) during a solar proton event in November 2004. Using the interferometric capabilities of ESRAD it was found that the scatterers responsible for PMWE show very high horizontal travel speeds, up to 500 ms-1 or more, and ...

    • Total Electron Content Measurements in the Ionosphere Disturbed by High-Power High-Frequency Waves by the Methods of Incoherent Scattering of Radio Waves and Radio Sounding by Glonass Satellite Signal 

      Tereshchenko, E. D.; Cherniakov, S. M.; Yurik, R. Yu.; Rietveld, Michael T; Häggström, I. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-06)
      We present the results of comparing the total electron content measurements based on GLONASS satellite signals and the EISCAT UHF incoherent scatter radar (Tromsø, Norway) during modification of the high-latitude ionosphere in the magnetic zenith direction by high-frequency radio waves of the EISCAT/Heating facility (Tromsø, Norway). The measurements were performed during two experiment campaigns ...