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

Abstract

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.

Low‐Frequency Wave Activity in the Ocean—Ross Ice Shelf—Atmosphere System

“…Vertical Incidence Pulsed Ionospheric Radar (VIPIR) equipped with the Dynasonde analysis software was installed at the Antarctic Jang Bogo Station (JBS, 74.62°S, 164.23°E geographic coordinates and 79.87°S geomagnetic latitude; see Figure 1) in 2015 but debugging and testing effort was complete only by 2017 (Ham et al., 2020; Kim et al., 2022; Kwon et al., 2018). Some of the early data are excessively noisy, but still useable for the kind of spectral studies we are presenting here.…”

“…The data set has been chosen because it overlaps with both seismometric array operation and the hydrophone deployment period. The ionospheric sounding system at JBS utilizes the Dynasonde mode of operation and the Dynasonde analysis software to perform HF echo recognition, ionogram inversion, and to produce ionospheric characteristics such as bottom‐side ionospheric electron density profiles with error bars, the F‐region maximum plasma frequency (foF2) and the peak height (hmF2), estimates for the speed of ion drifts, and ionospheric tilts (Kim et al., 2022; Rietveld et al., 2008; Zabotin et al., 2006). It is also very efficient in detection and characterization of ionospheric wave activity (Zabotin et al., 2017).…”

Dynasonde Observations of Ionospheric Polar Holes Under Quiet Geomagnetic Conditions at Jang Bogo Station, Antarctica

“…The data samples of V zon and V mer show a large vertical spread. The drift velocity shown in Figure 7 is calculated from a line‐of‐sight Doppler velocity ( V *), which is related to a phase difference (Δ θ ) of reflected radio echo signals and time delay (Δ t ) by the relation of Δ θ ( f ) = ( V */ c )4π f Δ t , where c is the speed of light and f is the radio wave frequency (Ham et al., 2020; Kim et al., 2022). Therefore, a large spread of the drift velocity comes from large variations in reflected echo phases.…”

“…As noted above, we examined all available ionogram data whether the Dynasonde software properly provides the density profile from the list of detected radio echoes and found that the ionogram data corresponding to blue data points did not represent the actual ionospheric density profile. This is due to the fact that the ionospheric structure is particularly complex and thus the autonomous Dynasonde software makes mistakes in trace selection (Kim et al., 2022).…”

Hemispheric Asymmetry of the Polar Ionospheric Density Investigated by ESR and JVD Radar Observations and TIEGCM Simulations for the Solar Minimum Period

“…Nonetheless, Kim et al. (2022) confirmed that the JVD measurements show relatively good correlations with GPS TECs for geomagnetically quiet times during solar minimum years. In order to perform the interhemispheric comparisons for the polar ionospheric density, we also used the field‐aligned measurements of electron density profiles from the 42‐m antenna of ESR at Longyearbyen (78.15°N, 16.02°E geographic coordinate and 75.6°N geomagnetic latitude), which was obtained from the Madrigal database v2.6.1 (http://isr.sri.com/madrigal/).…”