Articles | Volume 31, issue 6
https://doi.org/10.5194/angeo-31-1103-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/angeo-31-1103-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Regular paper
| 
21 Jun 2013
Regular paper |
| 21 Jun 2013
Observations of HF-induced instability in the auroral E region
N. M. Schlatter
School of Electrical Engineering, Royal Institute of Technology, Teknikringen 31, 10044 Stockholm, Sweden
N. Ivchenko
School of Electrical Engineering, Royal Institute of Technology, Teknikringen 31, 10044 Stockholm, Sweden
B. Gustavsson
EISCAT Scientific Association, Rymdcampus 1, 98192 Kiruna, Sweden
T. Leyser
Swedish Institute for Space Physics, Uppsala Division, Box 537, 751 21 Uppsala, Sweden
M. Rietveld
EISCAT Scientific Association, Ramfjordmoen, 9027 Ramfjordbotn, Norway
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Yoshimasa Tanaka, Yasunobu Ogawa, Akira Kadokura, Takehiko Aso, Björn Gustavsson, Urban Brändström, Tima Sergienko, Genta Ueno, and Satoko Saita
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2023-35, https://doi.org/10.5194/angeo-2023-35, 2023
Preprint under review for ANGEO
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We present by simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized-aurora computed tomography (G-ACT) method to modelled multiple auroral images and ionospheric electron density data. It is demonstrated that the G-ACT provides better reconstruction results than the normal ACT and can interpolate ionospheric electron density at a much higher spatial resolution than observed by EISCAT_3D radar.
Thomas B. Leyser, Tima Sergienko, Urban Brändström, Björn Gustavsson, and Michael T. Rietveld
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2023-21, https://doi.org/10.5194/angeo-2023-21, 2023
Revised manuscript accepted for ANGEO
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Powerful radio waves transmitted into the ionosphere from the ground were used to study electron energization in the pumped ionospheric plasma turbulence, by detecting optical emissions from atomic oxygen. Our results obtained with the EISCAT (European Incoherent SCATter association) facilities in northern Norway and optical detection with the ALIS (Auroral Large Imaging System) in northern Sweden suggest that long-wavelength upper hybrid waves are important in accelerating electrons.
Tinna L. Gunnarsdottir, Arne Poggenpohl, Ingrid Mann, Alireza Mahmoudian, Peter Dalin, Ingemar Haeggstroem, and Michael Rietveld
Ann. Geophys., 41, 93–114, https://doi.org/10.5194/angeo-41-93-2023, https://doi.org/10.5194/angeo-41-93-2023, 2023
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Temperatures at 85 km around Earth's poles in summer can be so cold that small ice particles form. These can become charged, and, combined with turbulence at these altitudes, they can influence the many electrons present. This can cause large radar echoes called polar mesospheric summer echoes. We use radio waves to heat these echoes on and off when the sun is close to or below the horizon. This allows us to gain some insight into these ice particles and how the sun influences the echoes.
Johann Stamm, Juha Vierinen, Björn Gustavsson, and Andres Spicher
Ann. Geophys., 41, 55–67, https://doi.org/10.5194/angeo-41-55-2023, https://doi.org/10.5194/angeo-41-55-2023, 2023
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The study of some ionospheric events benefit from the knowledge of how the physics varies over a volume and over time. Examples are studies of aurora or energy deposition. With EISCAT3D, measurements of ion velocity vectors in a volume will be possible for the first time. We present a technique that uses a set of such measurements to estimate electric field and neutral wind. The technique relies on adding restrictions to the estimates. We successfully consider restrictions based on physics.
Daniel K. Whiter, Noora Partamies, Björn Gustavsson, and Kirsti Kauristie
Ann. Geophys., 41, 1–12, https://doi.org/10.5194/angeo-41-1-2023, https://doi.org/10.5194/angeo-41-1-2023, 2023
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We measured the height of green and blue aurorae using thousands of camera images recorded over a 7-year period. Both colours are typically brightest at about 114 km altitude. When they peak at higher altitudes the blue aurora is usually higher than the green aurora. This information will help other studies which need an estimate of the auroral height. We used a computer model to explain our observations and to investigate how the green aurora is produced.
Mizuki Fukizawa, Takeshi Sakanoi, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Björn Gustavsson, Kirsti Kauristie, Alexander Kozlovsky, Tero Raita, Urban Brändström, and Tima Sergienko
Ann. Geophys., 40, 475–484, https://doi.org/10.5194/angeo-40-475-2022, https://doi.org/10.5194/angeo-40-475-2022, 2022
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The pulsating auroral generation mechanism has been investigated by observing precipitating electrons using rockets or satellites. However, it is difficult for such observations to distinguish temporal changes from spatial ones. In this study, we reconstructed the horizontal 2-D distribution of precipitating electrons using only auroral images. The 3-D aurora structure was also reconstructed. We found that there were both spatial and temporal changes in the precipitating electron energy.
Daniel K. Whiter, Hanna Sundberg, Betty S. Lanchester, Joshua Dreyer, Noora Partamies, Nickolay Ivchenko, Marco Zaccaria Di Fraia, Rosie Oliver, Amanda Serpell-Stevens, Tiffany Shaw-Diaz, and Thomas Braunersreuther
Ann. Geophys., 39, 975–989, https://doi.org/10.5194/angeo-39-975-2021, https://doi.org/10.5194/angeo-39-975-2021, 2021
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This paper presents an analysis of high-resolution optical and radar observations of a phenomenon called fragmented aurora-like emissions (FAEs) observed close to aurora in the high Arctic. The observations suggest that FAEs are not caused by high-energy electrons or protons entering the atmosphere along Earth's magnetic field and are, therefore, not aurora. The speeds of the FAEs and their internal dynamics were measured and used to evaluate theories for how the FAEs are produced.
Johann Stamm, Juha Vierinen, and Björn Gustavsson
Ann. Geophys., 39, 961–974, https://doi.org/10.5194/angeo-39-961-2021, https://doi.org/10.5194/angeo-39-961-2021, 2021
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Measurements of the electric field and neutral wind in the ionosphere are important for understanding energy flows or electric currents. With incoherent scatter radars (ISRs), we can measure the velocity of the ions, which depends on both the electrical field and the neutral wind. In this paper, we investigate methods to use ISR data to find reasonable values for both parameters. We find that electric field can be well measured down to 125 km height and neutral wind below this height.
Florine Enengl, Noora Partamies, Nickolay Ivchenko, and Lisa Baddeley
Ann. Geophys., 39, 795–809, https://doi.org/10.5194/angeo-39-795-2021, https://doi.org/10.5194/angeo-39-795-2021, 2021
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Energetic particle precipitation has the potential to change the neutral atmospheric temperature at the bottom of the ionosphere. We have searched for events and investigated a possible correlation between lower-ionosphere electron density enhancements and simultaneous neutral temperature changes. Six of the 10 analysed events are associated with a temperature decrease of 10–20K. The events change the chemical composition in the mesosphere, and the temperatures are probed at lower altitudes.
Torbjørn Tveito, Juha Vierinen, Björn Gustavsson, and Viswanathan Lakshmi Narayanan
Ann. Geophys., 39, 427–438, https://doi.org/10.5194/angeo-39-427-2021, https://doi.org/10.5194/angeo-39-427-2021, 2021
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This work explores the role of EISCAT 3D as a tool for planetary mapping. Due to the challenges inherent in detecting the signals reflected from faraway bodies, we have concluded that only the Moon is a viable mapping target. We estimate the impact of the ionosphere on lunar mapping, concluding that its distorting effects should be easily manageable. EISCAT 3D will be useful for mapping the lunar nearside due to its previously unused frequency (233 MHz) and its interferometric capabilities.
Minna Palmroth, Maxime Grandin, Theodoros Sarris, Eelco Doornbos, Stelios Tourgaidis, Anita Aikio, Stephan Buchert, Mark A. Clilverd, Iannis Dandouras, Roderick Heelis, Alex Hoffmann, Nickolay Ivchenko, Guram Kervalishvili, David J. Knudsen, Anna Kotova, Han-Li Liu, David M. Malaspina, Günther March, Aurélie Marchaudon, Octav Marghitu, Tomoko Matsuo, Wojciech J. Miloch, Therese Moretto-Jørgensen, Dimitris Mpaloukidis, Nils Olsen, Konstantinos Papadakis, Robert Pfaff, Panagiotis Pirnaris, Christian Siemes, Claudia Stolle, Jonas Suni, Jose van den IJssel, Pekka T. Verronen, Pieter Visser, and Masatoshi Yamauchi
Ann. Geophys., 39, 189–237, https://doi.org/10.5194/angeo-39-189-2021, https://doi.org/10.5194/angeo-39-189-2021, 2021
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This is a review paper that summarises the current understanding of the lower thermosphere–ionosphere (LTI) in terms of measurements and modelling. The LTI is the transition region between space and the atmosphere and as such of tremendous importance to both the domains of space and atmosphere. The paper also serves as the background for European Space Agency Earth Explorer 10 candidate mission Daedalus.
Johann Stamm, Juha Vierinen, Juan M. Urco, Björn Gustavsson, and Jorge L. Chau
Ann. Geophys., 39, 119–134, https://doi.org/10.5194/angeo-39-119-2021, https://doi.org/10.5194/angeo-39-119-2021, 2021
Alireza Mahmoudian, Mike J. Kosch, Wayne A. Scales, Michael T. Rietveld, and Henry Pinedo
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2020-81, https://doi.org/10.5194/angeo-2020-81, 2020
Preprint withdrawn
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The polar mesospheric summer echoes (PMSE) are very strong radar echoes observed in the frequency range of 2 MHz up to 1 GHz. Such radar echoes are attributed to the ice clouds formed in the mesosphere and are widely believed to link to global climate change. PMSEs are coherent echoes produced by plasma density fluctuations at half the radar wavelengts. This paper investigates the unresolved problem of short durability of plasma fluctuations at smaller wavelengths in upper atmospheric physics.
Michael T. Rietveld and Andrew Senior
Ann. Geophys., 38, 1101–1113, https://doi.org/10.5194/angeo-38-1101-2020, https://doi.org/10.5194/angeo-38-1101-2020, 2020
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We provide an explanation for mysterious radar echoes that look like increases in electron density during incoherent scatter radar measurements made when a high-power high-frequency (4–8 MHz) radio wave is transmitted up into the ionosphere. These echoes are seen at heights from about 200 to 650 km. We suggest that radar echoes at 930 MHz are guided along the earth's magnetic field by electron density irregularities created by the powerful radio wave, similar to light in an optical fibre.
Sam Tuttle, Betty Lanchester, Björn Gustavsson, Daniel Whiter, Nickolay Ivchenko, Robert Fear, and Mark Lester
Ann. Geophys., 38, 845–859, https://doi.org/10.5194/angeo-38-845-2020, https://doi.org/10.5194/angeo-38-845-2020, 2020
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Electric fields in the atmosphere near dynamic aurora are important in the physics of the electric circuit within the Earth's magnetic field. Oxygen ions emit light as they move under the influence of these electric fields; the flow of this emission is used to find the electric field at high temporal resolution. The solution needs two other simultaneous measurements of auroral emissions to give key parameters such as the auroral energy. The electric fields increase with brightness of the aurora.
Thomas B. Leyser, Björn Gustavsson, Theresa Rexer, and Michael T. Rietveld
Ann. Geophys., 38, 297–307, https://doi.org/10.5194/angeo-38-297-2020, https://doi.org/10.5194/angeo-38-297-2020, 2020
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Powerful radio waves transmitted into the ionosphere give the strongest turbulence effects in geomagnetic zenith, antiparallel to the magnetic field in the Northern Hemisphere. Our results obtained with the EISCAT (European Incoherent SCATter association) Heating facility in Norway and the EISCAT UHF incoherent scatter radar together with modelling suggest that the pump wave propagates in the L mode, rather than in the O mode that is usually assumed to be involved in such experiments.
Jun Wu, Jian Wu, Michael T. Rietveld, Ingemar Haggstrom, Haisheng Zhao, Tong Xu, and Zhengwen Xu
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2019-23, https://doi.org/10.5194/angeo-2019-23, 2019
Manuscript not accepted for further review
Gabriel Giono, Boris Strelnikov, Heiner Asmus, Tristan Staszak, Nickolay Ivchenko, and Franz-Josef Lübken
Atmos. Meas. Tech., 11, 5299–5314, https://doi.org/10.5194/amt-11-5299-2018, https://doi.org/10.5194/amt-11-5299-2018, 2018
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Energetic photons, such as ultraviolet light, are able to eject electrons from a material surface, thus creating an electrical current, also called a photocurrent. A proper estimation of this photocurrent can be crucial for space- or rocket-borne particle detectors, as it can dominate over the currents that are of scientific interest (induced by charged particles, for example). This article outlines the design for photocurrent modelling and for experimental confirmation in a laboratory.
Thomas B. Leyser, H. Gordon James, Björn Gustavsson, and Michael T. Rietveld
Ann. Geophys., 36, 243–251, https://doi.org/10.5194/angeo-36-243-2018, https://doi.org/10.5194/angeo-36-243-2018, 2018
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Transmission of powerful radio waves into the overhead ionosphere is used to study plasma turbulence processes. It is well known that the ionospheric response to radio waves is the strongest in the direction of the geomagnetic field. We have found evidence that the transmitted radio wave can propagate in a mode that enables the wave to propagate much higher in altitude and deeper into the ionosphere than what is usually expected, which may account for the strong plasma response observed.
Nickolay Ivchenko, Nicola M. Schlatter, Hanna Dahlgren, Yasunobu Ogawa, Yuka Sato, and Ingemar Häggström
Ann. Geophys., 35, 1143–1149, https://doi.org/10.5194/angeo-35-1143-2017, https://doi.org/10.5194/angeo-35-1143-2017, 2017
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Photo-electrons and secondary electrons from particle precipitation enhance the incoherent scatter plasma line to levels sufficient for detection. A plasma line gives an accurate measure of the electron density and can be used to estimate electron temperature. The occurrence of plasma line enhancements in the EISCAT Svalbard Radar data was investigated. During summer daytime hours the plasma line is detectable in up to 90 % of the data. In winter time the occurrence is a few percent.
Yunxia Yuan, Nickolay Ivchenko, Gunnar Tibert, Marin Stanev, Jonas Hedin, and Jörg Gumbel
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2017-91, https://doi.org/10.5194/amt-2017-91, 2017
Revised manuscript has not been submitted
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The paper presents a method to determine altitude profile of atmospheric density, temperature and wind by means of analysing the reconstructed trajectory of a rigid falling sphere released from a sounding rocket. The trajectory reconstruction is achieved by post-flight analysis of GPS raw data gathered in the sphere. A comparison of the results with independent measurements is presented, with good agreement of the falling sphere results with other sources in the stratosphere.
Hanna Dahlgren, Betty S. Lanchester, Nickolay Ivchenko, and Daniel K. Whiter
Ann. Geophys., 35, 493–503, https://doi.org/10.5194/angeo-35-493-2017, https://doi.org/10.5194/angeo-35-493-2017, 2017
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Pulsating aurora are ubiquitous events that constitute a large amount of energy transfer to the ionosphere. Still there are unsolved issues regarding their formation. Using high-resolution optical and radar data, we find that it is the flux of high-energy electrons that get reduced during the OFF period of the pulsations. We also report on dips in brightness at the transition between ON and OFF, and asymmetric rise and fall times, which may have implications for understanding the pulsations.
Hanna Dahlgren, Nicola M. Schlatter, Nickolay Ivchenko, Lorenz Roth, and Alexander Karlsson
Ann. Geophys., 35, 475–479, https://doi.org/10.5194/angeo-35-475-2017, https://doi.org/10.5194/angeo-35-475-2017, 2017
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Anomalous strong echoes with three frequency peaks are occasionally seen with incoherent scatter radars in the ionosphere near 200 km altitude at high latitudes. We investigate how they relate to electron precipitation, by finding the resulting peak electron density and the height of the peak, respectively. We find that occurrence rate increases with density and decreases with height, indicating a correlation between the echoes and precipitating electrons with high energy and energy flux.
B. Eliasson and T. B. Leyser
Ann. Geophys., 33, 1019–1030, https://doi.org/10.5194/angeo-33-1019-2015, https://doi.org/10.5194/angeo-33-1019-2015, 2015
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Large-amplitude radio waves lead to the structuring of the ionospheric plasma into groups magnetic field-aligned density cavities, or striations. A large part of the electromagnetic wave with ordinary mode polarization is then mode converted into upper hybrid waves trapped in the striations, further enforcing the striations. This simulation study investigates numerically this mode conversion and leakage of the the upper hybrid waves to back to electromagnetic waves in the Z-mode branch.
H. Y. Fu, W. A. Scales, P. A. Bernhardt, S. J. Briczinski, M. J. Kosch, A. Senior, M. T. Rietveld, T. K. Yeoman, and J. M. Ruohoniemi
Ann. Geophys., 33, 983–990, https://doi.org/10.5194/angeo-33-983-2015, https://doi.org/10.5194/angeo-33-983-2015, 2015
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This paper reports the first experimental observation of stimulated Brillouin scattering near the third electron gyro-harmonic induced by high-frequency, high-power radio waves at EISCAT. The stimulated Brillouin scattering has also been correlated with simultaneous observations of the
field-aligned irregularities and electron temperature. The observed stimulated Brillouin scattering becomes enhanced for pumping near electron gyro-harmonics.
N. M. Schlatter, V. Belyey, B. Gustavsson, N. Ivchenko, D. Whiter, H. Dahlgren, S. Tuttle, and T. Grydeland
Ann. Geophys., 33, 837–844, https://doi.org/10.5194/angeo-33-837-2015, https://doi.org/10.5194/angeo-33-837-2015, 2015
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The high-latitude ionosphere is a dynamic region where particle precipitation leads to various phenomena including wave instability and turbulence. Anomalous echoes related to aurora are observed in ground-based radar observations of the ionosphere. These echoes indicate enhanced ion acoustic fluctuations. In this article, we show that the origin of the echo is located in or close to the region of particle precipitation and that the echo region itself is limited to hundreds of meters.
O. Havnes, H. Pinedo, C. La Hoz, A. Senior, T. W. Hartquist, M. T. Rietveld, and M. J. Kosch
Ann. Geophys., 33, 737–747, https://doi.org/10.5194/angeo-33-737-2015, https://doi.org/10.5194/angeo-33-737-2015, 2015
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Noctilucent clouds were observed by two radars at different wavelengths. Artificial electron heating was applied. As predicted by modelling, there is a general difference between the observations by the two radars. However, for some heater cycles we observed an exceptionally strong, rapid and similar increase in backscatter for both radars when the heater was on. Models predict a considerable difference in reaction. Our observation indicate that the charging models may not be complete.
N. M. Schlatter, N. Ivchenko, T. Sergienko, B. Gustavsson, and B. U. E. Brändström
Ann. Geophys., 31, 1681–1687, https://doi.org/10.5194/angeo-31-1681-2013, https://doi.org/10.5194/angeo-31-1681-2013, 2013
W. Reid, P. Achtert, N. Ivchenko, P. Magnusson, T. Kuremyr, V. Shepenkov, and G. Tibert
Atmos. Meas. Tech., 6, 777–785, https://doi.org/10.5194/amt-6-777-2013, https://doi.org/10.5194/amt-6-777-2013, 2013
