We present a method for forecasting the foF2 and hmF2 parameters using modal decompositions from measured ionospheric electron density profiles. Our method is based on Dynamic Mode Decomposition (DMD), which provides a means of determining spatiotemporal modes from measurements alone. Our proposed extensions to DMD use wavelet decompositions that provide separation of a wide range of high-intensity, transient temporal scales in the measured data. This scale separation allows for DMD models to be fit on each scale individually, and we show that together they generate a more accurate forecast of the time-evolution of the F-layer peak. We call this method the Scale-Separated Dynamic Mode Decomposition (SSDMD). The approach is shown to produce stable modes that can be used as a time-stepping model to predict the state of foF2 and hmF2 at a high time resolution. 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.
This paper investigates the effects of geomagnetic storms of 25-27 September 2011, 16- 18 March 2013, and 6-8 September 2015 over five mid latitudes stations (Dourbes, Fairford, Moscow, Rome, and Roquetes) and performs a cross correlation analysis of ionospheric and solar parameters during these storms. We observed the highest fluctuations in ionospheric variables during the main phase of storms. In addition, there is strong evidence of pre-storm phenomenon occurring at least a few hours and more than 24 hours prior to the main phase of the geomagnetic storms. We found that the TEC and foF2 parameters have strong dependence with latitudes for the events with Sudden Storm Commencement(SSC) in mid latitude region. Relatively low TEC and foF2 can be observed in Moscow which is at the highest latitude among the five stations because of a decrease in the n(O)/n(N2) ratio through out the storm event. However, for the event with gradual storm commencement, there is no evidence of such dependence. The good correlation of Symmetric-H and Auroral Electrojet Indices with ionospheric parameters indicates that the coupling mechanism between magnetosphere and ionosphere produces intense electric field disturbances in the middle low latitudes.
Transionospheric radio signals might undergo random modulations of their amplitude and phase caused by scattering on irregular structures in the ionosphere. This phenomenon, known as scintillation, is governed by the space weather conditions, time of the day, season, local distribution of the geomagnetic field, etc. All these factors make ionospheric scintillation both highly variable in space and time. Moreover, scintillation are intrinsically anisotropic since the associated scattering irregularities tend to align and stretch along the geomagnetic field lines. Depending on the relative position of signal source, the receiving station, and the irregularity, the scintillation effect on the transmitted wave might be enhanced or reduced. This study is focused on the consistent accounting of this geometric effect in scintillation modeling with the emphasis on situations when the communication or sensing sender-receiver link is nearly horizontal. For this task the single phase screen model has been used to model the scattering of propagating radio signals on random ionospheric layer. The geometric enhancement effect of scintillation is demonstrated by considering communication links via a geostationary beacon satellite over the equator.