• 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 ...
    • The Cusp as a VLF Saucer Source: First Rocket Observations of Long‐Duration VLF Saucers on the Dayside 

      Moser, Chrystal; LaBelle, James William; Hatch, Spencer Mark; Moen, Jøran Idar; Spicher, Andres; Takahashi, Toru; Kletzing, Craig A.; Bounds, Scott Randolph; Oksavik, Kjellmar; Sigernes, Fred; Yeoman, Timothy K. (Journal article; Peer reviewed, 2021)
      Auroral whistler‐mode radio emissions called saucers are of fundamental interest because they require an unusually stationary emission process in the dynamic auroral environment, and it is a mystery how that can happen in ...
    • 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; Peer reviewed, 2021)
      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, ...
    • 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 ...
    • 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 ...
    • Inferring source properties of monoenergetic electron precipitation from kappa and Maxwellian moment‐voltage relationships 

      Hatch, Spencer Mark; LaBelle, James; Chaston, C. C. (Peer reviewed; Journal article, 2019)
    • 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 Effects of Plasma Pressure Gradients in the Upper F Region 

      Laundal, Karl Magnus; Hatch, Spencer Mark; Moretto, Therese (Peer reviewed; Journal article, 2019)
      The Swarm satellites fly at altitudes that at polar latitudes are generally assumed to only contain currents that are aligned with the local magnetic field. Therefore, disturbances along the main field direction are mainly ...
    • The Mansurov effect: Seasonal and solar wind sector structure dependence 

      Edvartsen, Jone Øvretvedt; Maliniemi, Ville Aleksi; Nesse, Hilde; Hatch, Spencer Mark (Journal article; Peer reviewed, 2023)
      We investigate the connection between the interplanetary magnetic field (IMF) By-component and polar surface pressure, also known as the Mansurov effect. The aim of the investigation is to unravel potential dependencies ...
    • The Mansurov effect: Statistical significance and the role of autocorrelation 

      Edvartsen, Jone Øvretvedt; Maliniemi, Ville Aleksi; Tyssøy, Hilde Nesse; Asikainen, Timo; Hatch, Spencer Mark (Journal article; Peer reviewed, 2022)
      The Mansurov effect is related to the interplanetary magnetic field (IMF) and its ability to modulate the global electric circuit, which is further hypothesized to impact the polar troposphere through cloud generation ...
    • Modulation of Magnetospheric Substorm Frequency: Dipole Tilt and IMF By Effects 

      Ohma, Anders; Reistad, Jone Peter; Hatch, Spencer Mark (Journal article; Peer reviewed, 2021)
      Substorm activity is heavily influenced by the Interplanetary Magnetic Field (IMF) Bz component and magnetospheric substorms occur most frequently when Bz is strongly negative. The substorm occurrence rate is also affected ...
    • Possible Ionospheric Influence on Substorm Onset Location 

      Elhawary, Reham Zakaria Ahmed Mohamed; Laundal, Karl Magnus; Reistad, Jone Peter; Hatch, Spencer Mark (Journal article; Peer reviewed, 2022)
      Auroral substorm onset locations are highly unpredictable. Previous studies have shown that the By component of the interplanetary magnetic field (IMF) explains ∼5% of the variation in onset magnetic local time (MLT), while ...
    • Quantifying the Lobe Reconnection Rate During Dominant IMF By Periods and Different Dipole Tilt Orientations 

      Reistad, Jone Peter; Laundal, Karl Magnus; Østgaard, Nikolai; Ohma, Anders; Burrell, Angeline G.; Hatch, Spencer Mark; Håland, Stein Egil; Thomas, Evan G. (Journal article; Peer reviewed, 2021)
      Lobe reconnection is usually thought to play an important role in geospace dynamics only when the Interplanetary Magnetic Field (IMF) is mainly northward. This is because the most common and unambiguous signature of lobe ...
    • The Relationship Between Cusp Region Ion Outflows and East-West Magnetic Field Fluctuations at 4,000-km Altitude 

      Hatch, Spencer Mark; Moretto, Therese; Lynch, Kristina A.; Laundal, Karl Magnus; Gjerloev, J.; Lund, Eric (Journal article; Peer reviewed, 2020)
      A number of interdependent conditions and processes contribute to ionospheric-origin energetic ( ∼ 10 eV to several keV) ion outflows. Due to these interdependences and the associated observational challenges, energetic ...
    • The relationship between interhemispheric asymmetries in polar ionospheric convection and the magnetic field line footpoint displacement field 

      Laundal, Karl Magnus; Madelaire, Michael; Ohma, Anders; Reistad, Jone Peter; Hatch, Spencer Mark (Journal article; Peer reviewed, 2022)
      Polar electrodynamics is largely controlled by solar wind and magnetospheric forcing. Different conditions can make plasma convection and magnetic field disturbances asymmetric between hemispheres. So far, these asymmetries ...
    • Seasonal and hemispheric asymmetries of F‐region polar cap plasma density: Swarm and CHAMP observations 

      Hatch, Spencer Mark; Haaland, Stein; Laundal, Karl Magnus; Moretto, Therese; Yau, Andrew; Bjoland, Lindis Merete; Reistad, Jone Peter; Ohma, Anders; Oksavik, Kjellmar (Journal article; Peer reviewed, 2020)
      One of the primary mechanisms of loss of Earth's atmosphere is the persistent “cold” ( urn:x-wiley:jgra:media:jgra56068:jgra56068-math-0001 20 eV) ion outflow that has been observed in the magnetospheric lobes over large ...
    • Spatial Resolution in Inverse Problems: The EZIE Satellite Mission 

      Madelaire, Michael; Laundal, Karl Magnus; Gjerloev, J.; Hatch, Spencer Mark; Reistad, Jone Peter; Vanhamäki, H.; Waters, Colin; Ohma, Anders; Mesquita, Rafael L. A.; Merkin, Viacheslav (Journal article; Peer reviewed, 2023)
      Inverse modeling has become one of the primary methods for studying ionospheric electrodynamics, especially when using magnetic field measurements from below the ionosphere. We present a method for quantifying the spatial ...
    • Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia 

      Walker, Simon; Laundal, Karl Magnus; Reistad, Jone Peter; Ohma, Anders; Hatch, Spencer Mark (Journal article; Peer reviewed, 2023)
      We present the implementation of an improved technique to coherently model the high-latitude ionospheric equivalent current. Using a fixed selection of 20 ground magnetometers in Fennoscandia, we present a method based on ...