Ionosonde Data

Data in our data server are updated daily, except on holidays and weekends.

Daily Height- Frequency-Time-Intensity plots (HFTI)
The frequency-time-intensity (FTI) plots are made at SGO for monitoring the critical frequency of the ionospheric E-layer (foE) and also sporadic E layers (foEs). From each ionogram, we take for each frequency the pixel of maximal power reflected from the height range 80-130 km. Then, these rows obtained from individual ionograms are turned vertical and placed side by side to obtain time profiles with color-coded signal intensity and frequency on the vertical axis.

For monitoring foF2, FTI plots are made at the height range 350-400 km.

Similar to the FTI plots, we also make height-time-intensity (HTI) plots for monitoring the virtual height of reflections. The HTI plots are color-coded plots of the intensity of the reflected signal at a fixed frequency in a frame of time and virtual height. Such plots are created by extracting vertical pixel columns at a fixed frequency from individual ionograms and putting the columns side by side. The horizontal axis is the time and the vertical axis is the virtual height.

NOTE: Our data are available free of charge for scientific and educational purposes. If our data are used for scientific publications, we require you to contact us in order to discuss under which conditions our data can be published, i.e. whether an acknowledgment of the Sodankylä Geophysical Observatory in your paper is sufficient or whether we require co-authorship. For detailed access to additional data, please contact our office or the observer in charge.
See the detailed data licence.