Improving ionospheric imaging via the incorporation of direct ionosonde observations into GPS tomography

The Multi Instrument Data Analysis system, MIDAS is an algorithm that images the ionosphere in three or four dimensions and was originally developed by Mitchell and Spencer (2003) [1]. MIDAS often operates using GPS measurements of slant Total Electron Content, but Chartier et al. [2012] [2] showed that incorporating ionosonde data into the algorithm could improve imaging of the ionosphere in the vertical dimension. Here we extend the technique to incorporation of multiple ionosondes, the key problem is to transition horizontally between regions of different peak height and changing densities. This approach is validated via comparisons with independent satellite data.