Modeling of the lower ionospheric response and VLF signal modulation during a total solar eclipse using ionospheric chemistry and LWPC

摘要: The variation in the solar Extreme Ultraviolet (EUV) radiation flux by any measure is most dominant natural source to produce perturbations or modulations ionospheric chemical and plasma properties. A solar eclipse, though a very rare phenomenon, similarly bound significant short time effect on local influence of ionizing reduction during eclipse lower ionosphere or, more precisely, D-region, can be studied with observation Very Low Frequency (VLF) radio wave signal modulation. interpretation such an VLF signals requires knowledge D-region ion chemistry, which not well till date. Dominant parameters govern as recombination coefficients, are poorly known. occurrence events provides us excellent opportunity investigate accuracy our condition this part Earth’s atmosphere properties control stability under disturbances. In paper, using existing physical we carry out effects obtained total 22 July 2009 signal. Data from week long campaign conducted Indian Centre for Space Physics (ICSP) over subcontinent has been used purpose. Both positive negative amplitude changes were observed along various receiver locations. data propagation path between Navy transmitter named VTX3 pair receivers India used. We start calculate ionization whole span influenced region range height. incorporate ion-chemistry model find equilibrium density employ LWPC code amplitude. To tackle uncertainty values coefficients explore evolution model. achieve two goals exercise: First, have able reproduce trends, if exact variation, at different receiving stations sufficient purely theoretical modeling, second some now improved.