Browsing Bergen Open Research Archive by Author "Laundal, Karl Magnus"

Now showing items 1-20 of 43

    • 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 ...

    • Auroral imaging as a tracer of global magnetospheric dynamics 

      Laundal, Karl Magnus (Doctoral thesis, 2010-11-12)

    • Auroral oval morphology: Dawn-dusk asymmetry partially induced by Earth’s rotation 

      Decotte, Margot Emilie; Laundal, Karl Magnus; Hatch, Spencer Mark; Reistad, Jone Peter (Journal article; Peer reviewed, 2023)
      The auroral oval morphology has been investigated in previous studies presenting maps of average auroral precipitation. However, such distributions tend to emphasize auroral intensity rather than the actual extent of the ...

    • Background removal from global auroral images: Data driven dayglow modelling 

      Ohma, Anders; Madelaire, Michael; Laundal, Karl Magnus; Reistad, Jone Peter; Hatch, Spencer Mark; Gasparini, Sara; Walker, Simon (Journal article; Peer reviewed, 2023)
      Global images of auroras obtained by cameras on spacecraft are a key tool for studying the near-Earth environment. However, the cameras are sensitive not only to auroral emissions produced by precipitating particles, but ...

    • 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 ...

    • 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 ...

    • 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 ...

    • Electrojet Estimates From Mesospheric Magnetic Field Measurements 

      Laundal, Karl Magnus; Yee, J.H.; Merkin, V.G.; Gjerløv, Jesper; Vanhamäki, H.; Reistad, Jone Peter; Madelaire, Michael; Sorathia, K.; Espy, Patrick Joseph (Journal article; Peer reviewed, 2021)
      The auroral electrojet is traditionally measured remotely with magnetometers on ground or in low Earth orbit (LEO). The sparse distribution of measurements, combined with a vertical distance of some 100 km to ground and ...

    • Evolution of IMF By induced asymmetries during substorms: Superposed epoch analysis at geosynchronous orbit 

      Ohma, Anders; Laundal, Karl Magnus; Reistad, Jone Peter; Østgaard, Nikolai (Journal article; Peer reviewed, 2022)
      The By component of the magnetic field inside the magnetosphere is positively correlated with the By component of the Interplanetary Magnetic Field (IMF). This leads to asymmetries in aurora, plasma convection and electric ...

    • Evolution of IMF By Induced Asymmetries: The Role of Tail Reconnection 

      Ohma, Anders; Østgaard, Nikolai; Laundal, Karl Magnus; Reistad, Jone Peter; Hatch, Spencer Mark; Tenfjord, Paul Arne Riksheim (Journal article; Peer reviewed, 2021)
      North-south asymmetries arise in the magnetosphere-ionosphere system when a significant east-west (By) component is present in the interplanetary magnetic field (IMF). During such conditions, a By component with the same ...

    • An explicit IMF By dependence on solar wind ‐ magnetosphere coupling 

      Reistad, Jone Peter; Laundal, Karl Magnus; Ohma, Anders; Moretto, Therese; Milan, Steve (Peer reviewed; Journal article, 2019)
      Presently, all empirical coupling functions quantifying the solar wind—magnetosphere energy—or magnetic flux conversion assume that the coupling is independent of the sign of the dawn-dusk component (B𝑦) of the Interplanetary ...

    • Exploring solar-terrestrial interactions via multiple imaging observers 

      Branduardi-Raymont, Graziella; Berthomier, M; Bogdanova, Y. V.; Carter, Jennifer; Collier, M; Dimmock, A; Dunlop, Malcolm; Fear, Robert C.; Forsyth, Colin; Hubert, Benoit; Kronberg, Elena A.; Laundal, Karl Magnus; Lester, Mark; Oksavik, Kjellmar; Østgaard, Nikolai; Palmroth, Minna; Plaschke, Ferdinand; Porter, F.S.; Rae, I. Jonathan; Read, Andy; Samsonov, A. A.; Sembay, Steven; Shprits, Yuri; Sibeck, David G.; Walsh, Brian; Yamauchi, M (Journal article; Peer reviewed, 2021)
      How does solar wind energy flow through the Earth’s magnetosphere, how is it converted and distributed? is the question we want to address. We need to understand how geomagnetic storms and substorms start and grow, not ...

    • Geomagnetic Response to Rapid Increases in Solar Wind Dynamic Pressure: Event Detection and Large Scale Response 

      Madelaire, Michael; Laundal, Karl Magnus; Reistad, Jone Peter; Hatch, Spencer Mark; Ohma, Anders; Haaland, Stein Egil (Journal article; Peer reviewed, 2022)
      Discontinuities in the solar wind trigger a variety of processes in the magnetosphere-ionosphere system. A rapid increase in solar wind dynamic pressure causes compression of the magnetosphere. This manifests itself as a ...

    • 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 ...

    • Interplanetary Magnetic Field Bx Component Influence on Horizontal and Field-Aligned Currents in the Ionosphere 

      Laundal, Karl Magnus; Reistad, Jone Peter; Finlay, Christopher C.; Østgaard, Nikolai; Tenfjord, Paul; Snekvik, Kristian; Ohma, Anders (Peer reviewed; Journal article, 2018-05)
      Statistical analyses have shown that the sunward component of the interplanetary magnetic field, Bx (Geocentric Solar Magnetospheric), moderately but significantly affects the auroral intensity. These observations have ...

    • Local Mapping of Polar Ionospheric Electrodynamics 

      Laundal, Karl Magnus; Reistad, Jone Peter; Hatch, Spencer Mark; Madelaire, Michael; Walker, Simon; Hovland, Amalie Øie; Ohma, Anders; Merkin, V.G.; Sorathia, K.A. (Journal article; Peer reviewed, 2022)
      An accurate description of the state of the ionosphere is crucial for understanding the physics of Earth's coupling to space, including many potentially hazardous space weather phenomena. To support this effort, ground ...

    • The Lompe code: A Python toolbox for ionospheric data analysis 

      Hovland, Amalie Øie; Laundal, Karl Magnus; Reistad, Jone Peter; Hatch, Spencer Mark; Walker, Simon; Madelaire, Michael; Ohma, Anders (Journal article; Peer reviewed, 2022)
      A recent paper by Laundal et al. (2022c) presented a new technique to combine all available measurements of polar ionospheric electrodynamics; magnetic field measurements from ground and space, ionospheric convection data ...

    • Magnetic coordinate systems 

      Laundal, Karl Magnus; Richmond, Arthur D. (Peer reviewed; Journal article, 2017-03)
      Geospace phenomena such as the aurora, plasma motion, ionospheric currents and associated magnetic field disturbances are highly organized by Earth’s main magnetic field. This is due to the fact that the charged particles ...