  We present a method for forecasting the foF2 and hmF2 parameters using modal
decompositions of ionospheric electron density profile time series. Our method
is based on the Dynamic Mode Decomposition (DMD), which provides a means of
determining spatiotemporal modes from measurements alone. DMD models are easily
updated as new data is recorded and do not require any physics to inform the
dynamics. However, in the case of ionospheric profiles, we find a wide range of
oscillations, including some far above the diurnal frequency. Therefore, we
propose nontrivial extensions to DMD using wavelet decompositions. We call this
method the Scale-Separated Dynamic Mode Decomposition (SSDMD) since the
wavelets isolate fluctuations at different time scales in the data into
separated components. We show that this method provides a stable reconstruction
of the peak plasma density and can be used to predict the state of foF2 and
hmF2 at future time steps. We demonstrate the SSDMD method on data sets
covering periods of high and low solar activity as well as low, mid, and high
latitude locations.
