Data Driven Ionospheric Mapping Technique for Wide Area Nowcasting

A new multidimensional mapping technique is being developed which determines the three dimensional electron density distribution of the ionosphere over a wide area of several thousand kilometers at any time, from sounder data recorded at the previous period just before this time. Electron density profiles from five Digisonde stations in the northeastern regions of the North American continent are used to describe the electron distribution in a 30 deg longitude by 30 deg latitude region. The time histories over 32 hours of the profiles (the polynomial coefficients) from each station are Fourier transformed to determine the spectral components. For each spectral component a damped plane wave is fitted to amplitudes and phases at the five stations. This analysis is performed for each of the profile coefficients, and zonal maps are constructed as sums of these plane waves. This nowcasting technique can find applications in ray tracing for OTH radar, HF communication and HF direction finding.