English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Powerful high-frequency (HF) radio waves can be used to efficiently modifythe upper-ionospheric plasmas of the F region. The pressure gradient induced bymodulated electron heating at ultralow-frequency (ULF) drives a localoscillating diamagnetic ring current source perpendicular to the ambientmagnetic field, which can act as an antenna radiating ULF waves. In thispaper, utilizing the HF heating model and the model of ULF wave generationand propagation, we investigate the effects of both the backgroundionospheric profiles at different latitudes in the daytime and nighttimeionosphere and the modulation frequency on the process of the HF modulatedheating and the subsequent generation and propagation of artificial ULFwaves. Firstly, based on a relation among the radiation efficiency of thering current source, the size of the spatial distribution of the modulatedelectron temperature and the wavelength of ULF waves, we discuss thepossibility of the effects of the background ionospheric parameters and themodulation frequency. Then the numerical simulations with both models areperformed to demonstrate the prediction. Six different background parametersare used in the simulation, and they are from the International ReferenceIonosphere (IRI-2012) model and the neutral atmosphere model (NRLMSISE-00),including the High Frequency Active Auroral Research Program (HAARP; 62.39° N, 145.15° W), Wuhan(30.52° N, 114.32° E) and Jicamarca (11.95° S,76.87° W) at 02:00 and 14:00 LT. A modulationfrequency sweep is also used in the simulation. Finally, by analyzing thenumerical results, we come to the following conclusions: in the nighttimeionosphere, the size of the spatial distribution of the modulated electrontemperature and the ground magnitude of the magnetic field of ULF wave arelarger, while the propagation loss due to Joule heating is smaller comparedto the daytime ionosphere; the amplitude of the electron temperatureoscillation decreases with latitude in the daytime ionosphere, while it increaseswith latitude in the nighttime ionosphere; both the electron temperatureoscillation amplitude and the ground ULF wave magnitude decreases as themodulation frequency increases; when the electron temperature oscillationis fixed as input, the radiation efficiency of the ring current source ishigher in the nighttime ionosphere than in the daytimeionosphere

Numerical study of the generation and propagation of ultralow-frequency waves by artificial ionospheric F region modulation at different latitudes