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In this paper, sub-ionospheric Very Low Frequency/Low Frequency (VLF/LF) radio signals over the North Atlantic zone and North Pacific zone have been analysed during the major Sudden Stratospheric Warming (SSW) event of January, 2009. Signals from the transmitters like, NAA (24.0 kHz) and NKR (37.5 kHz) received at Germany and signals from the transmitters like, NLK (24.8 kHz) and NPM (21.4 kHz) received...
Studies have revealed the Earth's ionosphere exhibits Earthquake precursory effects. The correlation between the ionosphere and Earthquakes has been studied extensively using Very Low Frequency (VLF) or Low Frequency (LF) radio signal. A connection between the Earth's magnetosphere and the ionosphere (through the linkage of the Earth's magnetic field) has also been established. It is known that solar...
The sub-ionospheric VLF signal strength varies significantly with place and time. The solar eclipse and regular solar terminator motion effects on the Global Ionospheric Weather (GIW) and hence the VLF propagation. It has been simulated considering wave guide mode theory of VLF radio signal propagation along various transmitter to receiver great circular paths. Using Long Wave Propagation Capability...
We report the results of our monitoring of the NWC transmitter from Khukurdaha (∼ 80 km away from Kolkata) during the partial solar eclipse (75%) of 15th January, 2010. The receiving station and the transmitter were on two opposite sides of the annular eclipse belt. We got clear depression in the data during the period of partial eclipse. However, most extraordinarily, there was a solar flare (spot...
We present the results of monitoring of four years (2005, 2007–09) of VLF signals collected in the Malda branch of ICSP, located in Malda, West Bengal and find the correlations, between the ionospheric activities and the earthquakes. Here we use that VLF signals which are transmitted from the VTX station (18.2 KHz). We first study the average signal throughout the year. We plot the so-called standardized...
The results of the analysis of the year-long (2007) monitoring of the night time data of the VLF signal amplitude from the Indian Navy station VTX at 18.2kHz, received at the Indian Centre for Space Physics, Kolkata, are presented. We analyzed this data to find out the correlation, if any, between the night time fluctuation and the seismic events. We found, using individual cases (with magnitudes...
Deviations of subionospheric VLF signal amplitude due to solar flares of several energy classes have been computed for the VLF signal propagating along the VTX-Kolkata baseline. Using Long Wave Propagation Capability Code (LWPC), the variation of the effective height h′ and steepness β parameters have been computed for X, M and C classes of solar flares. We compute the temporal variation of the electron...
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