Browsing Department of Physics and Technology by Journals "Geophysical Research Letters"

Now showing items 1-20 of 38

    • Analysis of Blue Corona Discharges at the Top of Tropical Thunderstorm Clouds in Different Phases of Convection 

      Dimitriadou, Krystallia; Chanrion, Olivier; Neubert, Torsten; Protat, Alain; Louf, Valentin; Heumesser, Matthias; Husbjerg, Lasse; Köhn, Christoph; Østgaard, Nikolai; Reglero, Victor (Journal article; Peer reviewed, 2022)
      We report on observations of corona discharges at the uppermost region of clouds characterized by emissions in a blue band of nitrogen molecules at 337 nm, with little activity in the red band of lightning leaders at 777.4 ...

    • Collisionless Magnetic Reconnection in an Asymmetric Oxygen Density Configuration 

      Kolstø, Håkon Midthun; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Tenfjord, Paul; Spinnangr, Susanne Flø; Kwagala, Norah Kaggwa (Journal article; Peer reviewed, 2020)
      Combined with the magnetic field, the distribution of charged particles in the inflow region is expected to control the rate of magnetic reconnection. This paper investigates how the reconnection process is altered by a ...

    • Constraining Spectral Models of a Terrestrial GammaRay Flash From a Terrestrial Electron Beam Observation by the Atmosphere-Space Interactions Monitor 

      Sarria, David Alexandre Stephan; Østgaard, Nikolai; Kochkin, Pavlo; Lehtinen, Nikolai Grigorievich; Mezentsev, Andrey; Marisaldi, Martino; Lindanger, Anders; Maiorana, Carolina; Carlson, Brant Edward; Neubert, Torsten; Reglero, Victor; Ullaland, Kjetil; Yang, Shiming; Genov, Georgi; Qureshi, Bilal Hasan; Budtz-Jørgensen, Carl; Kuvvetli, Irfan; Christiansen, Freddy; Chanrion, Olivier; Navarro-Gonzalez, Javier; Connel, P.; Eyles, Chris (Journal article; Peer reviewed, 2021)
      Terrestrial Gamma ray Flashes (TGFs) are short flashes of high energy photons, produced by thunderstorms. When interacting with the atmosphere, they produce relativistic electrons and positrons, and a part gets bounded to ...

    • 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 ...

    • Dayside Field-Aligned Current Impacts on Ionospheric Irregularities 

      Follestad, Anna Kristine Fæhn; Herlingshaw, Katie; Ghadjari, Hossein; Knudsen, David J.; McWilliams, Kathryn A.; Moen, Jøran Idar; Spicher, Andres; Wu, Jingjing; Oksavik, Kjellmar (Journal article; Peer reviewed, 2020)
      Global Navigation Satellite Systems (GNSS) are subject to disturbances caused by plasma irregularities in the ionosphere. Studies have suggested that in addition to the gradient drift and Kelvin‐Helmholtz instabilities, ...

    • The Dependence of Cold and Hot Patches on Local Plasma Transport and Particle Precipitation in Northern Hemisphere Winter 

      Zhang, Duan; Zhang, Qing-He; Ma, Y.-Z.; Oksavik, Kjellmar; Lyons, L.R.; Xing, Zan-Yang; Hairston, Marc; Deng, Z.-X.; Liu, J.-J. (Journal article; Peer reviewed, 2022)
      By using a database of 4,634 cold patches (high density and low electron temperature) and 4,700 hot patches (high density and high electron temperature) from Defense Meteorological Satellite Program F16 in 2005–2018 winter ...

    • Dependence of Sudden Stratospheric Warmings on Internal and External Drivers 

      Salminen, Antti; Asikainen, T.; Maliniemi, Ville Aleksi; Mursula, K. (Journal article; Peer reviewed, 2020)
      A sudden stratospheric warming (SSW) is a large-scale disturbance of the wintertime stratosphere, which occurs especially in the Northern Hemisphere. Earlier studies have shown that SSW occurrence depends on atmospheric ...

    • The Direct Effect of Medium Energy Electron Precipitation on Mesospheric Dynamics During a Sudden Stratospheric Warming Event in 2010 

      Zuniga Lopez, Hector Daniel; Tyssøy, Hilde Nesse; Smith-Johnsen, Christine; Maliniemi, Ville Aleksi (Journal article; Peer reviewed, 2022)
      Medium energy electron (MEE) (30–1,000 keV) precipitation enhances the production of nitric (NOx) and hydrogen oxides (HOx) throughout the mesosphere, which can destroy ozone (O3) in catalytic reactions. The dynamical ...

    • Directed Network of Substorms Using SuperMAG Ground‐Based Magnetometer Data 

      Orr, L; Chapman, Sandra c.; Gjerløv, Jesper (Peer reviewed; Journal article, 2019)
      We quantify the spatiotemporal evolution of the substorm ionospheric current system utilizing the SuperMAG 100+ magnetometers. We construct dynamical directed networks from this data for the first time. If the canonical ...

    • Do the Throat Auroras Create Polar Cap Patches? 

      Zhang, Duan; Zhang, Qing-He; Oksavik, Kjellmar; Xu, Tong; Xing, Zan-Yang; Lyons, L.R.; Han, De-Sheng; Zhang, Hong-Bo; Ma, Yu-Zhang; Hu, Ze-Jun; Liu, Jian-Jun; Wang, Yong; Wang, Xiang-Yu (Journal article; Peer reviewed, 2023)
      Throat auroras and polar cap patches are common phenomena in the polar ionosphere resulting from magnetosphere-ionosphere coupling. A campaign was organized, with all-sky imagers at Yellow River Station, the European ...

    • Electron Behavior Around the Onset of Magnetic Reconnection 

      Spinnangr, Susanne Flø; Hesse, Michael; Tenfjord, Paul Arne Riksheim; Norgren, Cecilia; Kolstø, Håkon Midthun; Kwagala, Norah Kaggwa; Jørgensen, Therese; Phan, Tai D. (Journal article; Peer reviewed, 2022)
      We investigate the onset of magnetic reconnection, utilizing a fully kinetic Particle-In-Cell (PIC) simulation. Characteristic features of the electron phase-space distributions immediately before reconnection onset are ...

    • Electron inflow velocities and reconnection rates at earth's magnetopause and magnetosheath 

      Burch, James L.; Webster, James M.; Hesse, Michael; Genestreti, Kevin J.; Denton, Richard E.; Phan, Tai D.; Hasegawa, Hiroshi; Cassak, Paul A.; Torbert, Roy B.; Giles, Barbara L.; Gershman, Daniel J.; Ergun, Robert E.; Russell, Christopher T.; Strangeway, Robert J.; Le Contel, Olivier; Pritchard, Kris R.; Marshall, Andrew T.; Hwang, Kyoung-Joo; Dokgo, Kyunghwan; Fuselier, Stephen A.; Chen, Li-Jen; Wang, Shan; Swisdak, Marc; Drake, James F.; Argall, Matthew R.; Trattner, Karlheinz J.; Yamada, Masaaki; Paschmann, Götz (Journal article; Peer reviewed, 2020)
      Electron inflow and outflow velocities during magnetic reconnection at and near the dayside magnetopause are measured using satellites from NASA's Magnetospheric Multiscale (MMS) mission. A case study is examined in detail, ...

    • Estimating the Rate of Cessation of Magnetospheric Activity in AMPERE Field‐Aligned Currents 

      Moretto, T; Hesse, Michael; Vennerstrøm, Susanne; Tenfjord, Paul (Peer reviewed; Journal article, 2018-12)
      The decay of magnetospheric activity when driving is turned off (to a minimum) was measured in total field‐aligned current estimates from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) ...

    • 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 ...

    • Global Frequency and Geographical Distribution of Nighttime Streamer Corona Discharges (BLUEs) in Thunderclouds 

      Soler, S.; Gordillo-Vázquez, F.J.; Pérez-Invernón, F. J.; Luque, Alejandro; Li, D.; Neubert, Torsten; Chanrion, Olivier; Reglero, Victor; Navarro-Gonzalez, Javier; Østgaard, Nikolai (Journal article; Peer reviewed, 2021)
      Blue LUminous Events (BLUEs) are transient corona discharges occurring in thunderclouds and characterized by strong 337.0 nm light flashes with absent (or weak) 777.4 nm component. We present the first nighttime climatology ...

    • Hydrogen Relative Permeability Hysteresis in Underground Storage 

      Lysyy, Maksim; Fernø, Martin; Ersland, Geir (Journal article; Peer reviewed, 2022)
      Implementation of the hydrogen economy for emission reduction will require storage facilities, and underground hydrogen storage (UHS) in porous media offers a readily available large-scale option. Lack of studies on ...

    • The Impact of Oxygen on the Reconnection Rate 

      Tenfjord, Paul; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Spinnangr, Susanne Flø; Kolstø, Håkon Midthun (Peer reviewed; Journal article, 2019-05-29)
      We investigate the role of a background oxygen population in magnetic reconnection, using particle‐in‐cell simulations. We run several simulations, with different initial oxygen temperatures and densities, to understand ...

    • Interferometric Study of Ionospheric Plasma Irregularities in Regions of Phase Scintillations and HF Backscatter 

      Spicher, Andres; LaBelle, James; Bonnell, John W.; Roglans, Roger; Moser, Chrystal; Fuselier, Stephen A.; Bounds, Scott; Clausen, Lasse; Di Mare, Francesca; Feltman, Connor A.; Jin, Yaqi; Kletzing, Craig; Miloch, Wojciech Jacek; Moen, Jøran Idar; Oksavik, Kjellmar; Sawyer, Rhyan; Takahashi, Toru; Yeoman, Tim K. (Journal article; Peer reviewed, 2022)
      We investigate the nature of small-scale irregularities observed in the cusp by the Twin Rockets to Investigate Cusp Electrodynamics-2 (TRICE-2) in regions of enhanced phase scintillations and high-frequency coherent radar ...

    • Ion Behaviors in the Reconnection Diffusion Region of a Corrugated Magnetotail Current Sheet 

      Wang, Shan; Chen, Li-Jen; Bessho, Naoki; Hesse, Michael; Giles, Barbara L; Moore, Thomas E (Journal article; Peer reviewed, 2019)
      The current sheet structure and ion behaviors in a magnetotail reconnection diffusion region are investigated. The multispacecraft analysis suggests a corrugated current sheet structure, interpreted as due to a flapping ...

    • 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 ...