Blar i forfatter "Løvhaug, Unni Pia"

Viser treff 1-8 av 8

    • The auroral red line polarisation: modelling and measurements 

      Lilensten, J.; Bommier, V.; Barthelemy, M; Lamy, Herve; Bernard, D; Moen, Jøran Idar; Johnsen, Magnar Gullikstad; Løvhaug, Unni Pia; Pitout, Frederic (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-12)
      In this work, we model the polarisation of the auroral red line using the electron impact theory developed by Bommier et al. (2011). This theory enables the computation of the distribution of the Degree of Linear Polarisation (DoLP) as a function of height if the flux of precipitated electrons is provided as input. An electron transport code is used to infer the stationary electron flux at each ...

    • Dynamic rayed aurora and enhanced ion-acoustic radar echoes 

      Blixt, Erik Mårten; Ivchenko, N.; Hagfors, T.; Grydeland, Tom; Trondsen, T.S.; La Hoz, Cesar; Lanchester, B.S.; Løvhaug, Unni Pia (Journal article; Tidsskriftartikkel; Peer reviewed, 2005-01-31)
      The generation mechanism for naturally enhanced ion-acoustic echoes is still debated. One important issue is how these enhancements are related to auroral activity. All events of enhanced ion-acoustic echoes observed simultaneously with the EISCAT Svalbard Radar (ESR) and with high-resolution narrow field-of-view auroral imagers have been collected and studied. Characteristic of all the ...

    • Effects of substorm electrojet on declination along concurrent geomagnetic latitudes in the northern auroral zone 

      Edvardsen, Inge; Johnsen, Magnar Gullikstad; Løvhaug, Unni Pia (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-02)
      The geomagnetic field often experiences large fluctuations, especially at high latitudes in the auroral zones. We have found, using simulations, that there are significant differences in the substorm signature, in certain coordinate systems, as a function of longitude. This is confirmed by the analysis of real, measured data from comparable locations. Large geomagnetic fluctuations pose ...

    • Electron Density Depletion Region Observed in the Polar Cap Ionosphere 

      Bjoland, Lindis Merete; Ogawa, Y.; Løvhaug, Unni Pia; Lorentzen, Dag Arne; Hatch, Spencer Mark; Oksavik, Kjellmar (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-16)
      This paper presents and discusses electron density depletion regions observed with the incoherent scatter EISCAT Svalbard Radar (ESR) located at 75.43°N geomagnetic latitude. The data include several decades of measurements, which make them suitable for studying statistical features and characteristics of the ionospheric parameters. Here we focus on the electron density depletions and their dependence ...

    • An evaluation of International Reference Ionosphere electron density in the polar cap and cusp using EISCAT Svalbard radar measurements 

      Bjoland, Lindis Merete; Belyey, Vasyl; Løvhaug, Unni Pia; La Hoz, Cesar (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-13)
      Incoherent scatter radar measurements are an important source for studies of ionospheric plasma parameters. In this paper the EISCAT Svalbard radar (ESR) long-term database is used to evaluate the International Reference Ionosphere (IRI) model. The ESR started operations in 1996, and the accumulated database up to 2012 thus covers 16 years, giving an overview of the ionosphere in the polar cap and ...

    • Interferometric radar observations of filamented structures due to plasma instabilities and their relation to dynamic auroral rays. 

      Grydeland, Tom; Hagfors, T.; Trondsen, T.S.; Blixt, Erik Mårten; Løvhaug, Unni Pia; La Hoz, Cesar (Journal article; Peer reviewed; Tidsskriftartikkel, 2004-04-02)
      Several explanations have been proposed for Naturally Enhanced ion-acoustic Echoes observed at midand high-latitude Incoherent Scatter observatories. A decisive measure for distinguishing between these explanations is whether or not simultaneously observed up- and downshifted enhancement occur simultaneously, or if they are the result of temporal and/or spatial averaging. The EISCAT Svalbard ...

    • On the nightglow polarisation for space weather exploration 

      Bosse, Léo; Lilensten, Jean; Gillet, Nicolas; Rochat, Sylvain; Delboulbé, Alain; Curaba, Stephane; Roux, Alain; Magnard, Yves; Johnsen, Magnar Gullikstad; Løvhaug, Unni Pia; Amblard, Pierre-Olivier; Le Bihan, Nicolas; Nabon, Maxime; Marif, Hanane; Auriol, Frédérique; Noûs, Camille (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-28)
      We present here observations of the polarisation of four auroral lines in the auroral oval and in the polar cusp using a new ground polarimeter called <i>Petit Cru</i>. Our results confirm the already known polarisation of the red line, and show for the first time that the three other lines observed here (namely 557.7 nm, 391.4 nm and 427.8 nm) are polarised as well up to a few percent. We show that ...

    • Particle precipitation during NEIAL events : simultaneous ground based nighttime observations at Svalbard 

      Lunde, June; Løvhaug, Unni Pia; Gustavsson, Björn Johan (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)