Observations of the Polar Ionosphere by the Vertical Incidence Pulsed Ionospheric Radar at Jang Bogo Station, Antarctica

Korea Polar Research Institute (KOPRI) installed an ionospheric sounding radar system called Vertical Incidence Pulsed Ionospheric Radar (VIPIR) at Jang Bogo Station (JBS) in 2015 in order to routinely monitor the state of the ionosphere in the auroral oval and polar cap regions. Since 2017, after two-year test operation, it has been continuously operated to produce various ionospheric parameters. In this article, we will introduce the characteristics of the JBS-VIPIR observations and possible applications of the data for the study on the polar ionosphere. The JBS-VIPIR utilizes a log periodic transmit antenna that transmits 0.5–25 MHz radio waves, and a receiving array of 8 dipole antennas. It is operated in the Dynasonde B-mode pulse scheme and utilizes the 3-D inversion program, called NeXtYZ, for the data acquisition and processing, instead of the conventional 1-D inversion procedure as used in the most of digisonde observations. The JBS-VIPIR outputs include the height profiles of the electron density, ionospheric tilts, and ion drifts with a 2-minute temporal resolution in the bottomside ionosphere. With these observations, possible research applications will be briefly described in combination with other observations for the aurora, the neutral atmosphere and the magnetosphere simultaneously conducted at JBS

Science goals for a high-frequency radar and radio imaging array

A medium and high-frequency antenna array for radar and radio imaging of the ionosphere is planned for installation in Aguadilla, Puerto Rico. Science goals include the study of space weather, radio propagation, meteors, lightning, and plasma physics. Radio imaging is ideal for the study of stimulated ionospheric radio emissions, such as those induced by the Arecibo Observatory high-power HF radio transmitter, which is likely to be restored to operation in the near future. The array will be complemented by a wide variety of instruments fielded by collaborators, and will be a rich source of student projects at all levels

Multiple Cusp Signatures in Ionograms Associated with Rocket-Induced Infrasonic Waves

We are interested in understanding how and when infrasonic waves propagate in the thermosphere, specifying the physical properties of those waves, and understanding how they affect radio wave propagation. We use a combination of traditional ionosonde observations and fixed frequency Doppler soundings to make high quality observations of vertically propagating infrasonic waves in the lower thermosphere/bottom side ionosphere. The presented results are the first simultaneous observations of infrasonic wave-induced deformations in ionograms and high-time-resolution observations of corresponding plasma displacements. Deformations in ionospheric echoes, which manifest as additional cusps and range variations, are shown to be caused by infrasonic wave-induced plasma displacements

Multiple Cusp Signatures in Ionograms Associated with Rocket-Induced Infrasonic Waves

We are interested in understanding how and when infrasonic waves propagate in the thermosphere, specifying the physical properties of those waves, and understanding how they affect radio wave propagation. We use a combination of traditional ionosonde observations and fixed frequency Doppler soundings to make high quality observations of vertically propagating infrasonic waves in the lower thermosphere/bottom side ionosphere. The presented results are the first simultaneous observations of infrasonic wave-induced deformations in ionograms and high-time-resolution observations of corresponding plasma displacements. Deformations in ionospheric echoes, which manifest as additional cusps and range variations, are shown to be caused by infrasonic wave-induced plasma displacements

OIASA application to oblique radio-sounding data recorded in Korea

The Oblique Ionogram Automatic Scaling Algorithm (OIASA) has been applied to a data set of oblique ionograms recorded by the Vertical Incidence Pulsed Ionospheric Radar, Version 2 (VIPIR2) ionosonde receiver in Korea. These ionograms are the result of the real-time oblique radio-soundings performed every 15 minutes since September 12, 2016 (day 256) between the Japanese National Institute of Communications Technology ionospheric stations of Kokubunji (35.71°N, 139.46°E), Yamagawa (31.18°N, 130.59°E), Ogimi (26.70°N, 128.12°E), and Sarabetsu (45.18°N, 141.76°E), and the Korean Space Weather Center stations of Icheon (37.14°N, 127.55°E) and Jeju (33.43°N, 126.29°E). A set of 288 poor-quality test mode ionograms for each of the 8 different radiolinks has been selected for this study, and the results are presented. In order to scale the Maximum Usable Frequencies (MUF) between the receiving and the transmitting ionosondes, a filtering procedure for the ionograms noise reduction has been applied in combination with an image recognition technique. Vertical equivalent ionograms have been then obtained using Martyn’s equivalent path theorem, and processed by Autoscala.UnpublishedVienna (Austria)2A. Fisica dell'alta atmosfer

Joint Observations with the Puerto Rico CubeSat, the Aguadilla Radio Array, and Arecibo Observatory

The ionosphere is a source of natural radio emissions in the low-frequency, medium-frequency, and high-frequency bands (0 to 30 MHz). In addition to natural emissions, artificial emissions can be stimulated using high-power radiowave ionospheric modification facilities, of which one is located at Arecibo Observatory in Puerto Rico. Two complementary projects are underway for the purpose of measuring stimulated radio emissions from the ionosphere above Arecibo. One involves the GimmeRF radio instrument, designed for 0 to 30 MHz vector observation of the radio electric field, and planned for launch on the Puerto Rico CubeSat. A second instrument, CARLO, will measure ion irregularities, temperature, and turbulence. The second project is the Aguadilla radio array, currently being installed at the Interamerican University Aguadilla Campus in northwestern Puerto Rico. The Aguadilla array is intended to measure 2 to 25 MHz radio images of the ionosphere, as well as to perform bistatic radar imaging of the ionosphere over Puerto Rico. Radio images produced by the Aguadilla array below the ionosphere can be directly compared with the radio data received by Puerto Rico CubeSat in-situ in the topside ionosphere, with the goal of better understanding the geometry and mechanisms of the radio emission processes

Assessment of Polar Ionospheric Observations by VIPIR/Dynasonde at Jang Bogo Station, Antarctica: Part 1—Ionospheric Densities

Vertical incidence pulsed ionospheric radar (VIPIR) has been operated to observe the polar ionosphere with Dynasonde analysis software at Jang Bogo Station (JBS), Antarctica, since 2017. The JBS-VIPIR-Dynasonde (JVD) provides ionospheric parameters such as the height profile of electron density with NmF2 and hmF2, the ion drift, and the ionospheric tilt in the bottomside ionosphere. The JBS (74.6°S, 164.2°E) is located in the polar cap, cusp, or auroral region depending on the geomagnetic activity and local time. In the present study, an initial assessment of JVD ionospheric densities is attempted by the comparison with GPS TEC measurements which are simultaneously obtained from the GPS receiver at JBS during the solar minimum period from 2017 to 2019. It is found that the JVD NmF2 and bottomside TEC (bTEC) show a generally good correlation with GPS TEC for geomagnetically quiet conditions. However, the bTEC seems to be less correlated with the GPS TEC with slightly larger spreads especially during the daytime and in summer, which seems to be associated with the characteristics of the polar ionosphere such as energetic particle precipitations and large density irregularities. It is also found that the Dynasonde analysis seems to show some limitations to handle these characteristics of the polar ionosphere and needs to be improved to produce more accurate ionospheric density profiles especially during disturbed conditions