Daria Kotova

• Kotova, Daria; Jin, Yaqi & Miloch, Wojciech Jacek (2022). Interhemispheric variability of the electron density and derived parameters by the Swarm satellites during different solar activity. Journal of Space Weather and Space Climate. ISSN 2115-7251. 12, s. 1–21. doi: 10.1051/swsc/2022007.
• Skjæveland, Arnlaug; Kotova, Daria S. & Miloch, Wojciech J. (2021). Case Studies of Ionospheric Plasma Irregularities Over Queen Maud Land, Antarctica. Journal of Geophysical Research (JGR): Space Physics. ISSN 2169-9380. 126(10). doi: 10.1029/2021JA029963. Fulltekst i vitenarkiv Vis sammendrag

  We use the first data set from the ground-based TEC and scintillation receiver located at the Norwegian Research Station Troll in Queen Maud Land, Antarctica to analyze in detail the ionospheric response during geomagnetic disturbances on February 26-27 and March 18-19, 2018. By combining the Troll data with complementary measurements (scintillation receivers, magnetometers, SuperDARN, DMSP satellites), we demonstrate that plasma irregularities above this part of Queen Maud Land can be associated with the expansion of the auroral oval, related structuring on its edges, as well as with strong flow shears in the evening and at nighttime, which are further modulated by the energetic particle precipitation. Phase scintillation indices correlate well with the magnetometer data.

• Kotova, Daria; Nosikov, I.A.; Klimenko, M.V. & Zakharov, V.E. (2021). Comparison оf Shooting Method and Variational Approach for Two-Point Ionospheric Ray Tracing. Bulletin of the Russian Academy of Sciences: Physics. ISSN 1062-8738. 85(3), s. 262–267. doi: 10.3103/S1062873821030114.
• Jin, Yaqi; Xiong, Chao; Clausen, Lasse Boy Novock; Spicher, Andres; Kotova, Daria & Brask, Steffen [Vis alle 9 forfattere av denne artikkelen] (2020). Ionospheric Plasma Irregularities Based on In Situ Measurements From the Swarm Satellites. Journal of Geophysical Research (JGR): Space Physics. ISSN 2169-9380. 125(7). doi: 10.1029/2020JA028103. Fulltekst i vitenarkiv Vis sammendrag

  In this study, we present global climatological distributions of ionospheric plasma irregularities based on measurements by the Swarm satellites. These first global statistics obtained by direct, in situ measurements of plasma variations with Swarm confirm the presence of three main regions of strong ionospheric irregularities: the magnetic equator extending from postsunset to early morning, in the auroral ovals (from dayside cusp to nightside), and inside the polar caps. At equatorial latitudes, ionospheric irregularities form two bands of enhanced plasma fluctuations centered around ±10° magnetic latitude. Due to different plasma processes, ionospheric irregularities at high and low latitudes show different distributions. Though the averaged intensity of plasma irregularities is weaker at equatorial latitudes than at high latitudes, the occurrence rate of significant plasma fluctuations (corresponding to extreme events) is much higher at the equator than that at high latitudes. Equatorial irregularities display clear seasonal and longitudinal variations; that is, they are most prominent over South America during the December solstice and are located over Africa during the June solstice. The magnitude of ionospheric irregularities at all latitudes is strongly controlled by the solar activity. Ionospheric irregularities become significantly weaker after 2016 during the current declining phase of solar activity. The interplanetary magnetic field Bz modulates the occurrence of ionospheric irregularities at both high and low latitudes.

• Ovodenko, Vladimir; Klimenko, Maxim; Zakharenkova, Irina; Oinats, Alexey; Kotova, Daria & Nikolaev, Alexander V. [Vis alle 14 forfattere av denne artikkelen] (2020). Spatial and Temporal Evolution of Different‐Scale Ionospheric Irregularities in Central and East Siberia During the 27–28 May 2017 Geomagnetic Storm. Space Weather. ISSN 1542-7390. 18(6). doi: 10.1029/2019SW002378. Fulltekst i vitenarkiv Vis sammendrag

  We present a multi‐instrumental study of ionospheric irregularities of different scales (from tens of centimeters to few kilometers) observed over the Central and East Siberia, Russia, during a moderate‐to‐strong geomagnetic storm on 27–28 May 2017. From high‐frequency (HF) and ultrahigh‐frequency (UHF) radar data, we observed an intense auroral backscatter developed right after the initial phase of the geomagnetic storm. Additionally, we examined variations of Global Positioning System (GPS)‐based ROT (rate of TEC changes, where TEC is total electron content) for available GPS receivers in the region. Ionosondes, HF, and UHF radar data exhibited a presence of intense multi‐scale ionospheric irregularities. We revealed a correlation between different‐scale Auroral/Farley‐Buneman ionospheric irregularities of the E layer during the geomagnetic storm. The combined analysis showed that an area of intense irregularities is well connected and located slightly equatorward to field‐aligned currents (FACs) and auroral oval at different stages of the geomagnetic storm. An increase and equatorward displacement of Region 1 (R1)/Region 2 (R2) FACs leads to appearance and equatorward expansion of ionospheric irregularities. During downward (upward) R1 FAC and upward (downward) R2 FAC, the eastward and upward (westward and downward) E × B drift of ionospheric irregularities occurred. Simultaneous disappearance of UHF/HF auroral backscatter and GPS ROT decrease occurred during a prolonged near noon reversal of R1 and R2 FAC directions that accompanied by R1/R2 FAC degradation and disappearance of high‐energy auroral precipitation.

• Kotova, Daria; Zakharenkova, Irina; Klimenko, Maxim; Ovodenko, Vladimir; Tyutin, Ilya & Chugunin, Dmitry V. [Vis alle 15 forfattere av denne artikkelen] (2020). Formation of Ionospheric Irregularities in the East Siberian Region during the Geomagnetic Storm of May 27─28, 2017. Russian Journal of Physical Chemistry B. ISSN 1990-7923. 14(2), s. 377–389. doi: 10.1134/S1990793120020232. Vis sammendrag

  Results of studying different-scale ionospheric irregularities on the basis of multi-instrumental data, obtained in the East Siberian region of Russia during the geomagnetic storm of May 27–28, 2017, are presented. Spatial inhomogeneities of electron density in the ionosphere were observed through data from ground-based receivers of signals of global navigational satellite systems and on the basis of direct measurements of electron density in low-orbit satellites. An intense radio aurora was seen in UHF radar data just after the initial phase of geomagnetic storm. At the same time, we recorded fluctuations of the total electron content from data of GPS receivers and the presence of E-layer irregularities by data of the ionosonde in Norilsk. The time of irregularity recording by different instruments is consistent with the spatiotemporal changes in field-aligned currents of the second zone, obtained from data of AMPERE low-orbit satellite system.

• Kotova, Daria; Ovodenko, Vladimir; Yasyukevich, Yury; Klimenko, Maxim; Ratovsky, Konstantin & Mylnikova, Anna [Vis alle 11 forfattere av denne artikkelen] (2019). Efficiency of updating the ionospheric models using total electron content at mid- and sub-auroral latitudes. GPS Solutions. ISSN 1080-5370. 24. doi: 10.1007/s10291-019-0936-x. Vis sammendrag

  Describing the current ionospheric conditions is crucial to solving problems of radio communication, radar, and navigation. Techniques to update ionospheric models using current measurements found a wide application to improve the ionosphere description. We present the results of updating the NeQuick and IRI-Plas empirical ionosphere models using the slant total electron content observed by ground-based GPS/GLONASS receivers. The updating method is based on calculating the effective value of the solar activity index, which allows minimizing the discrepancy between the measured and the modelcalculated slant TEC. We estimated the updating efficiency based on the foF2 observational data obtained by ionosonde measurements. We calculated the data for 4 stations: Irkutsk, Norilsk, Kaliningrad, and Sodankylä. We analyzed 4 days in 2014: March 22, June 22, September 22, and December 18. We found that, in some cases, upon updating, the IRI-Plas underestimates the foF2, whereas NeQuick, on the contrary, overestimates it. We found a seasonal dependence of the updating efficiency of the ionosphere model using slant TEC. Possible causes of this dependence might be associated with the seasonal dependence of the correctness of model’s reproduction of the latitude–longitude TEC distribution. In general, we found the low level of the updating efficiency of the foF2 using slant TEC. This can be mainly explained by the fact that the models describe the electron density vertical profile and ionospheric slab thickness incorrectly

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• Kotova, Daria & Miloch, Wojciech Jacek (2021). Study of the GNSS phase scintillation associated with auroral activity over Queen Maud Land, Antarctica. Vis sammendrag

  This study uses the dataset from the all-sky camera and the ground-based TEC and scintillation receiver installed in Antarctica at the Norwegian Research Station Troll. The station is located just on the equatorward edge of the quiet auroral oval. Thus, the observatory is in an optimal location to study the ionospheric response to geomagnetic disturbances. The all-sky camera was calibrated. In addition, we use geomagnetic indices and information about the solar wind from NASA's OMNIWeb Service, in-situ data onboard low Earth orbiting satellites (Defense Meteorological Satellite Program (DMSP), Swarm mission), and the Super Dual Auroral Radar Network (SuperDARN). Together with the ground-based GNSS scintillation receiver, a comprehensive analysis of the reasons for observing scintillations over the Troll station during the period of geomagnetic disturbances was carried out. The relationship between the activation of aurora and severe phase scintillations is shown.

• Kotova, Daria (2021). Comprehensive analysis of scintillations over the Troll station using the all-sky camera and GNSS receiver. Vis sammendrag

  In this study, we use the first data from the all-sky camera installed in Antarctica at the Norwegian Research Station Troll. The auroral all-sky camera calibration was calibrated. Together with the ground-based TEC and scintillation receiver located there, a comprehensive analysis of the reasons for observing scintillations over the Troll station during the period of geomagnetic disturbances was carried out.

• Kotova, Daria; Jin, Yaqi & Miloch, Wojciech Jacek (2021). Investigation of interhemispheric variability of ionospheric parameters by the Swarm satellites for different solar activity. Vis sammendrag

  The use of satellite data allows us to study the variability of ionospheric plasma parameters globally without references to ground stations or receivers in different regions of the Earth. The Swarm mission, which was launched in 2014 and is still operational, allows us to investigate the effects of decreasing solar activity on the ionospheric variability. In our study, we use the Swarm in-situ measurements of the electron density and derived parameters. This dataset provides characteristics of the plasma variability along the orbit and gives information on plasma density structures in the ionosphere in terms of their amplitudes, gradients and spatial scales. In this study, we focused on the investigation of variability of these parameters in northern and southern hemispheres. Understanding of the distribution of such parameters in the context of the solar activity level and selected ionospheric regions can have implications for the development of new satellite instruments and for the accuracy of GNSS precise positioning.

• Miloch, Wojciech Jacek; Jin, Yaqi; Xiong, Chao; Brask, Steffen Mattias; Kotova, Daria & Kervalishvili, Guram [Vis alle 9 forfattere av denne artikkelen] (2020). Ionospheric Plasma IRregularities (IPIR data products).
• Kotova, Daria; Klimenko, Maxim; Vesnin, Artem; Klimenko, Vladimir V.; Zakharov, Veniamin & Rogov, Denis D. [Vis alle 7 forfattere av denne artikkelen] (2020). SIMULATION OF OBLIQUE SOUNDING IONOGRAMS DURING ST. PATRICK'S DAY 2015 GEOMAGNETIC STORM: VALIDATION AND INVESTIGATION OF THE INFLUENCE OF THE EARTH'S MAGNETIC FIELD. Proceedings of International Conference "Atmosphere, ionosphere, safety" (AIS-2020). s. 132–135.
• Kotova, Daria; Jin, Yaqi; Brask, Steffen; Cilliers, Pierre & Miloch, Wojciech Jacek (2020). Comparison of characteristics of electron density fluctuations from Swarm satellites with the ground-based scintillation dat.
• Kotova, Daria; Jin, Yaqi & Miloch, Wojciech Jacek (2020). Variability of ionospheric parameters by the Swarm satellites for different solar activity.
• Kotova, Daria; Nosikov, Igor; Klimenko, Maxim & Bessarab, Pavel (2020). Comparison of two approaches for a point-to-point radio wave ray tracing in anisotropic medium.
• Miloch, Wojciech Jacek; Kotova, Daria; Jin, Yaqi; Xiong, Chao; Brask, Steffen & Kervalishvili, Guram [Vis alle 9 forfattere av denne artikkelen] (2019). Ionospheric plasma irregularities studied globally with the Swarm satellites .
• Kotova, Daria; Jin, Yaqi & Miloch, Wojciech Jacek (2019). Comparison of ionospheric plasma irregularities measured by Swarm with the ground-based GPS scintillation data. Vis sammendrag

  Ionospheric irregularities are often the cause of GNSS precise positioning errors, as well as disruption of radio communications in the HF range. The reason for the occurrence of these irregularities can be various non-stationary processes in the near-Earth space plasma that depend on the response of the ionosphere to the variations in the near Earth space. Therefore, the study of ionospheric irregularities is an urgent scientific and applied problem. In this study we use a global product based on the Swarm satellite measurements that characterizes ionospheric irregularities and fluctuations. The IPIR (Ionospheric Plasma IRregularities product) provides characteristics of plasma density structures in the ionosphere, of plasma irregularities in terms of their amplitudes, gradients and spatial scales and assigns them to geomagnetic regions and consequently to predominant plasma processes. It also provides indication, in the form of a numerical value index, on their severity for the integrity of trans-ionospheric radio signals and hence the accuracy of GNSS precise positioning. In this work we made validations of the IPIR product against the ground-based measurements, focusing on GPS TEC and scintillation data in low latitudes regions.

• Skjæveland, Arnlaug Høgås; Kotova, Daria & Miloch, Wojciech Jacek (2019). Investigation of GPS phase scintillations at Troll station during geomagnetic disturbances in 2018. Vis sammendrag

  Ionospheric phenomena as a response to geomagnetic activity can be different at both hemispheres, in particular at high latitudes, due to the structure of the ionosphere, orientation of the interplanetary magnetic field and structure of the Earth magnetic field. This may have implications on large scale modeling and space weather forecasting. To understand these aspects, a significant number of studies which include both hemispheres are required. In order to study the asymmetry between the northern and southern hemispheres at high latitudes, we employ the GNSS TEC and scintillation monitors. We use data from a GNSS receiver at Troll station in Antarctica together with corresponding datasets from the northern hemisphere. We carry out detailed study of several representative events for different geomagnetic conditions. We characterize the GPS phase scintillations in the context of interhemispheric asymmetries, and also using other supportive ground based and satellite observations. This is the first study with data from the recently established ionospheric observatory at Troll station in Antarctica. It also forms a ground for more statistical study of interhemispheric asymmetries, where the first results are also shown.

• Kotova, Daria; Nosikov, Igor & Klimenko, Maxim (2019). Comparison of two approaches for point-to-point ray tracing of HF waves in the ionosphere.
• Kotova, Daria; Ovodenko, Vladimir; Klimenko, Maxim; Karpov, Mikhail; Ratovsky, Konstantin & Korenkova, Nina [Vis alle 8 forfattere av denne artikkelen] (2019). Statistical analysis of results of updating the ionospheric model IRI-Plas from slant total electron content.

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