A COMPARATIVE STUDY OF MEASURED AMPLITUDE AND PHASE PERTURBATIONS OF VLF AND LF RADIO SIGNALS INDUCED BY SOLAR FLARES

Serbian Astronomical Journal

article

D. M. Suli´ ˇ c¹  V. A. Sre´ckovi´c² 

[1] University Union - Nikola Tesla Belgrade;Institute of Physics, University of Belgrade

关键词: solar-terrestrial relations;    Sun: activity;    Sun: flares;    Sun: X-rays;    gamma rays;    X-rays: bursts;   

DOI  :  10.2298/SAJ1488045S

来源: Astronomical Observatory, Department of Astronomy, Belgrade

【 摘 要 】

Very Low Frequency (VLF) and Low Frequency (LF) signal perturbations were examined to study ionospheric disturbances induced by solar X-ray flares in order to understand processes involved in propagation of VLF/LF radio signals over short paths and to estimate specific characteristics of each short path. The receiver at the Belgrade station is constantly monitoring the amplitude and phase of a coherent and subionospherically propagating LF signal operated in Sicily NSC at 45.90 kHz, and a VLF signal operated in Isola di Tavolara ICV at 20.27 kHz, with the great circle distances of 953 km and 976 km, respectively. A significant number of similarities between these short paths is a direct result of both transmitters and the receiver’s geographic location. The main difference is in transmitter frequencies. From July 2008 to February 2014 there were about 200 events that were chosen for further examination. All selected examples showed that the amplitude and phase of VLF and LF signals were perturbed by solar X-ray flares occurrence. This six-year period covers both minimum and maximum of solar activity. Simultaneous measurement of amplitude and phase of the VLF/LF signals during a solar flare occurrence was applied to evaluate the electron density profile versus altitude, to carry out the function of time over the middle Europe.

【 授权许可】

CC BY-NC-ND