Numerical modeling of seasonal and diurnal variations of lower ionospheric reflection parameters based on IRI model

Very Low Frequency (VLF) remote sensing technique is used to probe the D-layer modeling for which we use a very conventional model known as Wait
^′
s 2-component ionospheric model. This model is characterized by two ionospheric parameters which are ‘steepness parameter’ (β) and ‘effective reflection height’ (h
^′
). International Reference Ionosphere (IRI 2012) model is an empirical standard model of the ionosphere, based on all available data sources. In this paper, we compute an electron density profile of the ionospheric D-layer by using IRI model under an ionospheric quiet condition for the year 2016 from altitude range 65 km to 85 Km at the VLF reception station IERCOO/ICSP, Sitapur [Lat 22.5
^◦
N, Lon 87.48
^◦
E]. By numerically best fitting, we compare it with Wait
^′
s empirical formula. Using an auto-generated process we repeat this procedure for several times and computed an authorized data set of Wait
^′
s parameters (β and h
^′
) for four locations viz. Kolkata, Kathmandu, Pune, and Bhuj for the different time of the day and for the entire year. Using linear equation as a best fit to the altitude profile, we try to compute the actual data set of β and h
^′
for the entire path of the various location of India and its subcontinent for VTX (18.2 kHz) transmitter for summer (July, 2009) and winter (December, 2008) period. By this data set, we showed the seasonal and diurnal variation of these two characteristic parameters behaviors and also using these parameters and Long Wavelength Propagation Capability (LWPC), we generate a spatio-temporal profile of simulated VLF signal amplitude for several baselines.