• The asymmetric geospace as displayed during the geomagnetic storm on 17 August 2001 

      Østgaard, Nikolai; Reistad, Jone Peter; Tenfjord, Paul; Laundal, Karl Magnus; Rexer, Theresa; Haaland, Stein; Snekvik, Kristian; Hesse, Michael; Milan, Stephen Eric; Ohma, Anders (Peer reviewed; Journal article, 2018-11-29)
      Previous studies have shown that conjugate auroral features are displaced in the two hemispheres when the interplanetary magnetic field (IMF) has a transverse (Y) component. It has also been shown that a BY component is ...
    • Birkeland current effects on high-latitude ground magnetic field perturbations 

      Laundal, Karl Magnus; Haaland, Stein; Lehtinen, Nikolai; Gjerløv, Jesper; Østgaard, Nikolai; Tenfjord, Paul; Reistad, Jone Peter; Snekvik, Kristian; Milan, Steve; Ohtani, Shin-ichi; Anderson, Brian J. (Peer reviewed; Journal article, 2015-09-18)
      Magnetic perturbations on ground at high latitudes are directly associated only with the divergence-free component of the height-integrated horizontal ionospheric current, J⊥,df. Here we show how J⊥,df can be expressed as ...
    • Can magnetotail reconnection produce the auroral intensities observed in the conjugate ionosphere? 

      Østgaard, Nikolai; Snekvik, Kristian; Borg, Anette Lauen; Åsnes, Arne; Pedersen, Arne; Øieroset, Marit; Phan, Tai D.; Haaland, Stein (Peer reviewed; Journal article, 2009-06)
      [1] In a recent case study, Borg et al. (2007) reported that an inverted V structure, caused by a field-aligned potential drop of 30 kV producing very strong X-ray aurora, was found in connection with tail reconnection. ...
    • Characteristics of the flank magnetopause: Cluster observations 

      Haaland, Stein; Reistad, Jone Peter; Tenfjord, Paul; Gjerloev, Jesper W.; Maes, Lukas; deKeyser, Johan; Maggiolo, Romain; Anekallu, Chrandrasehkar; Dorville, Nicolas (Peer reviewed; Journal article, 2014-11)
      The magnetopause is a current sheet forming the boundary between the geomagnetic field on one side and the shocked solar wind on the other side. This paper discusses properties of the low-latitude dawn and dusk flanks of ...
    • Characteristics of the Flank Magnetopause: THEMIS Observations 

      Haaland, Stein; Runov, Andrei; Artemyev, Anton; Angelopoulos, Vassillis (Peer reviewed; Journal article, 2019-05-30)
      The terrestrial magnetopause is the boundary that shields the Earth's magnetosphere on one side from the shocked solar wind and its embedded interplanetary magnetic field on the other side. In this paper, we show observations ...
    • Cluster observations of a field aligned current at the dawn flank of a bursty bulk flow 

      Snekvik, Kristian; Haaland, Stein; Østgaard, Nikolai; Hasegawa, H.; Nakamura, R.; Takada, T.; Juusola, L.; Amm, O.; Pitout, F.; Rème, H.; Klecker, B.; Lucek, E. A. (Peer reviewed; Journal article, 2007-06-29)
      This article describes observations of a bursty bulk flow (BBF) in the outer central plasma sheet. The observations are made with the Cluster satellites, located approximately 19RE downtail, close to the midnight sector ...
    • Dawn-dusk asymmetries in the coupled solar wind-magnetosphere-ionosphere system: a review 

      Walsh, Andrew P.; Haaland, Stein; Forsyth, Colin; Keesee, Amy M.; Kissinger, Jennifer; Li, Kun; Runov, Andrei; Soucek, Josef; Walsh, Brian M.; Wing, Simon; Taylor, Matthew G.G.T. (Peer reviewed; Journal article, 2014-07-01)
      Dawn–dusk asymmetries are ubiquitous features of the coupled solar-wind–magnetosphere–ionosphere system. During the last decades, increasing availability of satellite and ground-based measurements has made it possible to ...
    • Dayside and nightside magnetic field responses at 780 km altitude to dayside reconnection 

      Snekvik, Kristian; Østgaard, Nikolai; Tenfjord, Paul; Reistad, Jone Peter; Laundal, Karl Magnus; Milan, Stephen Eric; Haaland, Stein (Peer reviewed; Journal article, 2017-02)
      During southward interplanetary magnetic field, dayside reconnection will drive the Dungey cycle in the magnetosphere, which is manifested as a two‐cell convection pattern in the ionosphere. We address the response of the ...
    • Distribution of energetic oxygen and hydrogen in the near-Earth plasma sheet 

      Kronberg, Elena A.; Grigorenko, Elena; Haaland, Stein; Daly, Patrick W.; Delcourt, Dominique C.; Luo, Hao; Kistler, Lynn M.; Dandouras, Iannis (Peer reviewed; Journal article, 2015-05)
      The spatial distributions of different ion species are useful indicators for plasma sheet dynamics. In this statistical study based on 7 years of Cluster observations, we establish the spatial distributions of oxygen ions ...
    • Dynamic effects of restoring footpoint symmetry on closed magnetic field lines 

      Reistad, Jone Peter; Østgaard, Nikolai; Tenfjord, Paul; Laundal, Karl Magnus; Snekvik, Kristian; Haaland, Stein; Milan, Steve; Oksavik, Kjellmar; Frey, H. U.; Grokott, A. (Peer reviewed; Journal article, 2016-05-05)
      Here we present an event where simultaneous global imaging of the aurora from both hemispheres reveals a large longitudinal shift of the nightside aurora of about 3 h, being the largest relative shift reported on from ...
    • Estimating the fate of oxygen ion outflow from the high-altitude cusp 

      Krcelic, Patrik; Haaland, Stein; Maes, Lukas; Slapak, Rikard; Schillings, Audrey (Journal article; Peer reviewed, 2020)
      We have investigated the oxygen escape-to-capture ratio from the high-altitude cusp regions for various geomagnetic activity levels by combining EDI and CODIF measurements from the Cluster spacecraft. Using a magnetic field ...
    • Estimation of cold plasma outflow during geomagnetic storms 

      Haaland, Stein; Eriksson, A.; Maes, L.; Baddeley, Lisa; Barakat, A.; Chappell, R.; Eccles, V.; Johnsen, C.; Lybekk, Bjørn; Li, K.; Pedersen, A; Schunk, R.; Welling, D. (Peer reviewed; Journal article, 2015-12-01)
      Low-energy ions of ionospheric origin constitute a significant contributor to the magnetospheric plasma population. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and ...
    • The Hall current system revealed as a statistical significant pattern during fast flows 

      Snekvik, Kristian; Nakamura, R.; Østgaard, Nikolai; Haaland, Stein; Retinò, A. (Peer reviewed; Journal article, 2008-11-05)
      We have examined the dawn-dusk component of the magnetic field, BY , in the night side current sheet during fast flows in the neutral sheet. 237 h of Cluster data from the plasma sheet between 2 August 2002 and 2 October ...
    • How the IMF By induces a By component in the closed magnetosphere and how it leads to asymmetric currents and convection patterns in the two hemispheres 

      Tenfjord, Paul; Østgaard, Nikolai; Snekvik, Kristian; Laundal, Karl Magnus; Reistad, Jone Peter; Haaland, Stein; Milan, Steve (Peer reviewed; Journal article, 2015-11-12)
      We used the Lyon-Fedder-Mobarry global magnetohydrodynamics model to study the effects of the interplanetary magnetic field (IMF) By component on the coupling between the solar wind and magnetosphere-ionosphere system. ...
    • The impact of sunlight on high-latitude equivalent currents 

      Laundal, Karl Magnus; Gjerløv, Jesper; Østgaard, Nikolai; Reistad, Jone Peter; Haaland, Stein; Snekvik, Kristian; Tenfjord, Paul; Ohtani, Shin-ichi; Milan, Steve (Peer reviewed; Journal article, 2016-03)
      Ground magnetic field measurements can be mathematically related to an overhead ionospheric equivalent current. In this study we look in detail at how the global equivalent current, calculated using more than 30 years of ...
    • Intensity asymmetries in the dusk sector of the poleward auroral oval due to IMF Bx 

      Reistad, Jone Peter; Østgaard, Nikolai; Laundal, Karl Magnus; Haaland, Stein; Tenfjord, Paul; Snekvik, Kristian; Oksavik, Kjellmar; Milan, Steve (Peer reviewed; Journal article, 2014-12)
      In the exploration of global-scale features of the Earth's aurora, little attention has been given to the radial component of the Interplanetary Magnetic Field (IMF). This study investigates the global auroral response in ...
    • Magnetospheric response and reconfiguration times following IMF By reversals 

      Tenfjord, Paul Arne Riksheim; Østgaard, Nikolai; Strangeway, Robert J.; Haaland, Stein; Snekvik, Kristian; Laundal, Karl Magnus; Reistad, Jone Peter; Milan, Stephen Eric (Peer reviewed; Journal article, 2017-01)
      The interaction between the interplanetary magnetic field (IMF) and the geomagnetic field at the dayside magnetopause leads to transfer of momentum and energy which changes the magnetospheric configuration, but only after ...
    • Mass‐loading the Earth's dayside magnetopause boundary layer and its effect on magnetic reconnection 

      Fuselier, Stephen; Trattner, K.J.; Petrinec, Steve M.; Denton, Mike; Toledo, Sergio P.A.; Andrè, M.; Aunai, N; Chappell, Charles Richard; Glocer, Alex; Haaland, Stein; Hesse, Michael; Kistler, Lynn M.; Li, Wenya; Moore, T. E.; Graham, Daniel B.; Alm, Love; Tenfjord, Paul; Dargen, Jeremy; Vines, Sarah; Nykyri, K.; Burch, James L; Strangeway, Robert J. (Peer reviewed; Journal article, 2019)
      When the interplanetary magnetic field is northward for a period of time, O+ from the high‐latitude ionosphere escapes along reconnected magnetic field lines into the dayside magnetopause boundary layer. Dual‐lobe reconnection ...
    • MMS Observations of Multiscale Hall Physics in the Magnetotail 

      Alm, Love; André, Mats; Graham, Daniel B.; Khotyaintsev, Yuri V.; Vaivads, Andris; Chappell, Charles Richard; Dargent, Jérémy; Fuselier, Stephen A.; Haaland, Stein; Lavraud, Benoit; Li, Wenya; Tenfjord, Paul; Toledo-Redondo, Sergio; Vines, Sarah K. (Journal article; Peer reviewed, 2019)
      We present Magnetospheric Multiscale mission (MMS) observations of Hall physics in the magnetotail, which compared to dayside Hall physics is a relatively unexplored topic. The plasma consists of electrons, moderately cold ...
    • North-south asymmetries in cold plasma density in the magnetotail lobes: Cluster observations 

      Haaland, Stein; Lybekk, Bjørn; Maes, Lukas; Laundal, Karl Magnus; Pedersen, Amund; Tenfjord, Paul; Ohma, Anders; Østgaard, Nikolai; Reistad, Jone Peter; Snekvik, Kristian (Peer reviewed; Journal article, 2017-01)
      In this paper, we present observations of cold (0–70 eV) plasma density in the magnetotail lobes. The observations and results are based on 16 years of Cluster observation of spacecraft potential measurements converted ...