Blar i Bergen Open Research Archive på forfatter "Lorentzen, Dag Arne"

Viser treff 1-16 av 16

    • Dynamic properties of throat aurora revealed by simultaneous ground and satellite observations 

      Chen, Xiangcai; Han, Desheng; Lorentzen, Dag Arne; Oksavik, Kjellmar; Moen, Jøran Idar; Baddeley, Lisa (Peer reviewed; Journal article, 2017-03)
      Throat aurora is defined as south-north aligned auroral arcs equatorward of the dayside cusp aurora and was suggested to be the results of cold magnetospheric plasma interaction with magnetopause reconnection, but its ...

    • 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, ...

    • GPS scintillation and irregularities at the front of an ionization tongue in the nightside polar ionosphere 

      van der Meeren, Christer; Oksavik, Kjellmar; Lorentzen, Dag Arne; Moen, Jøran Idar; Romano, Vincenzo (Peer reviewed; Journal article, 2014-10)
      In this paper we study a tongue of ionization (TOI) on 31 October 2011 which stretched across the polar cap from the Canadian dayside sector to Svalbard in the nightside ionosphere. The TOI front arrived over Svalbard ...

    • How Often Do Thermally Excited 630.0 nm Emissions Occur in the Polar Ionosphere? 

      Kwagala, Norah Kaggwa; Oksavik, Kjellmar; Lorentzen, Dag Arne; Johnsen, Magnar Gullikstad (Peer reviewed; Journal article, 2018-01)
      This paper studies thermally excited emissions in the polar ionosphere derived from European Incoherent Scatter Svalbard radar measurements from the years 2000–2015. The peak occurrence is found around magnetic noon, where ...

    • An investigation into the spectral parameters of ultra-low-frequency (ULF) waves in the polar caps and magnetotail 

      Nosikova, Nataliya Sergeevna; Yagova, Nadezda Viktorovna; Baddeley, Lisa; Lorentzen, Dag Arne; Sormakov, Dmitriy Anatolyevich (Journal article; Peer reviewed, 2022)
      The present case study is focused on fluctuations at ∼ 1.5 mHz observed on open field lines in both of the polar caps in ground-based geomagnetic data and in the electron concentration in the Northern Hemisphere ionosphere. ...

    • Observations of sunlit N2+ aurora at high altitudes during the RENU2 flight 

      Ellingsen, Pål Gunnar; Lorentzen, Dag Arne; Kenward, David; Hecht, James H.; Evans, J. Scott; Sigernes, Fred; Lessard, Marc (Journal article; Peer reviewed, 2021)
      We present measurements of sunlit aurora during the launch of the Rocket Experiment for Neutral Upwelling 2 (RENU2) on the 13 December 2015, 07:34 UTC. The in situ auroral conditions coincide with those of sunlit aurora ...

    • On the contribution of thermal excitation to the total 630.0 nm emissions in the northern cusp ionosphere 

      Kwagala, Norah Kaggwa; Oksavik, Kjellmar; Lorentzen, Dag Arne; Johnsen, Magnar Gullikstad (Peer reviewed; Journal article, 2017-01)
      Direct impact excitation by precipitating electrons is believed to be the main source of 630.0 nm emissions in the cusp ionosphere. However, this paper investigates a different source, 630.0 emissions caused by thermally ...

    • The red-sky enigma over Svalbard in December 2002 

      Sigernes, Fred; Lloyd, N.; Lorentzen, Dag Arne; Neuber, R.; Hoppe, U.-P.; Degenstein, D.; Shumilov, N.; Moen, Jøran Idar; Gjessing, Yngvar; Havnes, Ove; Skartveit, Arvid; Raustein, Elmer; Ørbæk, J.B.; Deehr, CS (Peer reviewed; Journal article, 2005)
      On 6 December 2002, during winter darkness, an extraordinary event occurred in the sky, as viewed from Longyearbyen (78° N, 15° E), Svalbard, Norway. At 07:30 UT the southeast sky was surprisingly lit up in a deep red ...

    • Scintillation and irregularities from the nightside part of a Sun-aligned polar cap arc 

      van der Meeren, Christer; Oksavik, Kjellmar; Lorentzen, Dag Arne; Paxton, Larry J.; Clausen, Lasse Boy Novock (Peer reviewed; Journal article, 2016-06-18)
      In this paper we study the presence of irregularities and scintillation in relation to the nightside part of a long-lived, Sun-aligned transpolar arc on 15 January 2015. The arc was observed in DMSP UV and particle data ...

    • Scintillation and loss of signal lock from poleward moving auroral forms in the cusp ionosphere 

      Oksavik, Kjellmar; van der Meeren, Christer; Lorentzen, Dag Arne; Baddeley, Lisa; Moen, Jøran Idar (Journal article, 2015-10-27)
      We present two examples from the cusp ionosphere over Svalbard, where poleward moving auroral forms (PMAFs) are causing significant phase scintillation in signals from navigation satellites. The data were obtained using a ...

    • Seasonal and Solar Cycle Variations of Thermally Excited 630.0 nm Emissions in the Polar Ionosphere 

      Kwagala, Norah Kaggwa; Oksavik, Kjellmar; Lorentzen, Dag Arne; Johnsen, Magnar Gullikstad; Laundal, Karl Magnus (Peer reviewed; Journal article, 2018-08)
      Solar cycle and seasonal variations have been found in the occurrence of strong thermally excited 630.0 nm emissions in the polar ionosphere. Measurements from the European Incoherent Scatter Svalbard Radar have been used ...

    • Severe and localized GNSS scintillation at the poleward edge of the nightside auroral oval during intense substorm aurora 

      van der Meeren, Christer; Oksavik, Kjellmar; Lorentzen, Dag Arne; Rietveld, Michael T.; Clausen, Lasse Boy Novock (Peer reviewed; Journal article, 2015-12)
      In this paper we study how GPS, GLONASS, and Galileo navigation signals are compromised by strong irregularities causing severe phase scintillation (σϕ>1) in the nightside high-latitude ionosphere during a substorm on 3 ...

    • Space and atmospheric physics on Svalbard: a case for continued incoherent scatter radar measurements under the cusp and in the polar cap boundary region 

      Baddeley, Lisa; Lorentzen, Dag Arne; Haaland, Stein Egil; Heino, Erkka Petteri; Mann, Ingrid Brigitte; Miloch, Wojciech Jacek; Oksavik, Kjellmar; Partamies, Noora; Spicher, Andres; Vierinen, Juha-Pekka (Journal article; Peer reviewed, 2023)
      Incoherent scatter radars (ISRs) represent the only instrument (both ground and space based) capable of making high temporal and spatial resolution measurements of multiple atmospheric parameters—such as densities, ...

    • A statistical study of polar cap flow channels and their IMF by dependence 

      Herlingshaw, Katie; Baddeley, Lisa; Oksavik, Kjellmar; Lorentzen, Dag Arne (Journal article; Peer reviewed, 2020)
      An algorithm to detect high-speed ionospheric flow channels (FCs) in the polar cap was applied to data from the Longyearbyen radar of the Super Dual Auroral Radar Network. The Longyearbyen radar is at high latitude (78.2°N, ...

    • A statistical study of polar cap flow channels observed in both hemispheres using SuperDARN radars 

      Herlingshaw, Katie; Baddeley, Lisa; Oksavik, Kjellmar; Lorentzen, Dag Arne; Laundal, Karl Magnus (Journal article; Peer reviewed, 2022)
      This paper details the first large-scale, interhemispheric statistical study into ionospheric fast flow (>900 m/s) channels in the polar cap using the SuperDARN radar network. An automatic algorithm was applied to 6 years ...

    • A Study of Automatically Detected Flow Channels in the Polar Cap Ionosphere 

      Herlingshaw, Katie; Baddeley, Lisa; Oksavik, Kjellmar; Lorentzen, Dag Arne; Bland, Emma (Peer reviewed; Journal article, 2019-11-13)
      This paper presents a new algorithm for detecting high‐speed flow channels in the polar cap. The algorithm was applied to Super Dual Auroral Radar Network data, specifically to data from the new Longyearbyen radar. This ...