Study of separation in junction frequency in vertical incidence ionogram traces observed at low-mid latitude Indian station, New Delhi: Ionosonde observations

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics Pub Date : 2025-02-01 DOI:10.1016/j.jastp.2024.106414

Arti Bhardwaj , Anshul Singh , Qadeer Ahmed , Ankit Gupta , A.K. Upadhayaya

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引用次数: 0

Abstract

Ionogram traces split into two modes, ordinary (O) and extraordinary (X), in the F-layer due to magneto-ionic splitting, where a transmitted pulse propagates in two distinct ways under the influence of Earth's magnetic field. The Earth's magnetic field causes ionogram traces to show double hop echoes when an echo is reflected back upward by the ground and then re-reflected by the ionosphere, demonstrating that the ionosphere is a doubly refracting medium. We have investigated the separation in Junction frequencies (JFs) of the O and X modes in vertical incidence ionogram traces observed over a seven-year period (2014–2020) during the declining phase of the solar cycle, from maximum to minimum. This difference in splitting in two modes is expected to be 0.67 MHz at low-mid latitude Indian station, New Delhi (28.6°N, 77.2°E). Anomalous separations of more than 21% in JFs were observed during the analysis. In these cases, we found over 30% anomalous cases of JFs in different seasons, with the highest occurrence in summer, followed by equinox and winter. JFs followed diurnal variation, with heightened variation during the solar cycle maxima and minimal variation during solar cycle minima. Lastly, we observed a concurrency between JFs and ionospheric perturbations caused by phenomena originating in both the lower and upper atmosphere.

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来源期刊

Journal of Atmospheric and Solar-Terrestrial Physics 地学-地球化学与地球物理

CiteScore

4.10

自引率

5.30%

发文量

审稿时长

6 months

期刊介绍： The Journal of Atmospheric and Solar-Terrestrial Physics (JASTP) is an international journal concerned with the inter-disciplinary science of the Earth''s atmospheric and space environment, especially the highly varied and highly variable physical phenomena that occur in this natural laboratory and the processes that couple them. The journal covers the physical processes operating in the troposphere, stratosphere, mesosphere, thermosphere, ionosphere, magnetosphere, the Sun, interplanetary medium, and heliosphere. Phenomena occurring in other "spheres", solar influences on climate, and supporting laboratory measurements are also considered. The journal deals especially with the coupling between the different regions. Solar flares, coronal mass ejections, and other energetic events on the Sun create interesting and important perturbations in the near-Earth space environment. The physics of such "space weather" is central to the Journal of Atmospheric and Solar-Terrestrial Physics and the journal welcomes papers that lead in the direction of a predictive understanding of the coupled system. Regarding the upper atmosphere, the subjects of aeronomy, geomagnetism and geoelectricity, auroral phenomena, radio wave propagation, and plasma instabilities, are examples within the broad field of solar-terrestrial physics which emphasise the energy exchange between the solar wind, the magnetospheric and ionospheric plasmas, and the neutral gas. In the lower atmosphere, topics covered range from mesoscale to global scale dynamics, to atmospheric electricity, lightning and its effects, and to anthropogenic changes.