Bibliography

Morphologies of ionospheric-equivalent slab-thickness and scale height over equatorial latitude in Africa

Accurate representation of ionospheric equivalent slab thickness (τ) and scale height (Hm) plays a crucial role in characterizing the complex dynamics of topside and bottomside ionospheric constituents. In the present work, we examined the corresponding morphologies of ionospheric profile parameters with collocated global positioning system (GPS) and Digisonde Portable Sounder (DPS) setups at an equatorial location in west Africa Ilorin (8.50°N, 4.68°E), during a low solar activity year 2010. The extracted τ from GPS and DPS in selected quiet periods confirm it to be a first-order measure of Hm over Africa. The seasonal analysis of τ shows substantial enhancement in the magnitude during the post-sunset and solstice seasons, of which December solstice manifests relatively higher values than June solstice. This result could be associated with the elevation of the meridional wind and drift in the parameters, which are more substantial during the post-noon and solstices. Therefore, at solstices, the post-night increase could indicate solar cycle dynamics during HSA (high solar activity) and LSA (low solar activity). However, the extracted Hm from its relationship with τ did not show visible effects of dynamics in E × B plasma drift and the meridional wind. In our study, a decline in morphologies of Hm and τ from December solstice to June solstice through the equinox is not consistent with the existing observations at mid-latitude. The results would complement the relationships between bottomside and topside profile peak parameters and dynamics of ionospheric constituents for a realistic representation and modeling of the ionosphere over African equatorial and low latitude regions. Thus, it also contributes to the global effort of improving ionospheric prediction and forecasting models.

Odeyemi, Olumide; Adeniyi, Jacob; Oyeyemi, Elijah; Panda, Sampad; Jamjareegulgarn, Punyawi; Olugbon, Busola; Oluwadare, Esholomo; Akala, Andrew; Olawepo, Adeniji; Adewale, Adekola;

Published by: Advances in Space Research      Published on: jan

YEAR: 2022     DOI: 10.1016/j.asr.2021.10.030

Global positioning system; Digital portable sounder; Equatorial latitude; Equivalent slab thickness; scale height

Transpolar Arcs During a Prolonged Radial Interplanetary Magnetic Field Interval

Transpolar arcs (TPAs) are believed to predominantly occur under northward interplanetary magnetic field (IMF) conditions with their hemispheric asymmetry controlled by the Sun-Earth (radial) component of the IMF. In this study, we present observations of TPAs that appear in both the northern and southern hemispheres even during a prolonged interval of radially oriented IMF. The Defense Meteorological Satellite Program (DMSP) F16 and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellites observed TPAs on the dawnside polar cap in both hemispheres (one TPA structure in the southern hemisphere and two in the northern hemisphere) during an interval of nearly earthward-oriented IMF on October 29, 2005. The southern hemisphere TPA and one of the northern hemisphere TPAs are associated with electron and ion precipitation and mostly sunward plasma flow (with shears) relative to their surroundings. Meanwhile, the other TPA in the northern hemisphere is associated with an electron-only precipitation and antisunward flow relative to its surroundings. Our observations indicate the following: (a) the TPA formation is not limited to northward IMF conditions; (b) the TPAs can be located on both closed field lines rooted in the polar cap of both hemispheres and open field lines connected to the northward field lines draped over one hemisphere of the magnetopause. We believe that the TPAs presented here are the result of both indirect and direct processes of solar wind energy transfer to the high-latitude ionosphere.

Park, Jong-Sun; Shi, Quan; Nowada, Motoharu; Shue, Jih-Hong; Kim, Khan-Hyuk; Lee, Dong-Hun; Zong, Qiu-Gang; Degeling, Alexander; Tian, An; Pitkänen, Timo; Zhang, Yongliang; Rae, Jonathan; Hairston, Marc;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2021     DOI: 10.1029/2021JA029197

radial IMF; solar wind-magnetosphere-ionosphere coupling; transpolar arc

Energy Transfer in the Solar Wind-Magnetosphere-Ionosphere System Under Radial Interplanetary Magnetic Field Conditions: Implication of Transpolar Arcs

Park, Jong-Sun; Shi, Quanqi; Nowada, Motoharu; Shue, Jih-Hong; Kim, Khan-Hyuk; Lee, Dong-Hun; Zong, Qiugang; Degeling, Alexander; Tian, Anmin; Pitkänen, Timo; , others;

Published by:       Published on:

YEAR: 2019     DOI:

Variations of the neutral temperature and sodium density between 80 and 107 km above Troms\o during the winter of 2010-2011 by a new solid-state sodium lidar

A new solid-state sodium lidar installed at Ramfjordmoen, Troms\o (69.6\textdegreeN, 19.2\textdegreeE), started observations of neutral temperature together with sodium density in the mesosphere-lower thermosphere (MLT) region on 1 October 2010. The new lidar provided temperature data with a time resolution of 10 min and with good quality between \~80 and \~105 km from October 2010 to March 2011. This paper aims at introducing the new lidar with its observational results obtained over the first 6 months of observations. We succeeded in obtaining neutral temperature and sodium density data of \~255.5 h in total. In order to evaluate our observations, we compared (1) the sodium density with that published in the literature, (2) average temperature and column sodium density data with those obtained with Arctic Lidar Observatory for Middle Atmosphere Research Weber sodium lidar, and (3) the neutral temperature data with those obtained by Sounding of the Atmosphere with Broadband Emission Radiometry/Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. For the night of 5 October 2010, we succeeded in conducting simultaneous observations of the new lidar and the European Incoherent Scatter UHF radar with the tristatic Common Program 1 (CP-1) mode. Comparisons of neutral and ion temperatures showed a good agreement at 104 km between 0050 and 0230 UT on 6 October 2010 when the electric field strength was smaller, while significant deviations (up to \~25 K) are found at 107 km. We evaluated contributions of Joule heating and electron-ion heat exchange, but derived values seem to be underestimated.

Nozawa, S.; Kawahara, T.; Saito, N.; Hall, C.; Tsuda, T.; Kawabata, T.; Wada, S.; Brekke, A.; Takahashi, T.; Fujiwara, H.; Ogawa, Y.; Fujii, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2014

YEAR: 2014     DOI: 10.1002/2013JA019520

Joule heating; neutral temperature; polar MLT; sodium lidar