A four-dimensional image of the ionosphere was developed over Scandinavia
The ionosphere is the atmospheric layer between about 80 and 700 km height, where gases are electrically charged. As a consequence, in this layer electric processes take place, such as the northern lights, and possible disturbance of electronic systems on the ground.
Ionospheric tomography is usually used to image very large structures (> 1000 km) over a wide area. At FMI, this technique has been developed further to image medium-scale structures: between 100 km and 2000 km in horizontal size. The technique is demonstrated for data of December 2006 above Scandinavia. Software received from the University of Bath, UK, was specially adapted for this purpose.
The input consists of measurements of GPS satellite signals by the dense GPS network Geotrim in Finland. EISCAT ionospheric radar data measured Tromsø, Norway, are used as additional input, to provide sufficient vertical resolution to the result. Results are presented and compared with direct measurements: EISCAT radar results, direct GPS results and measurements of signals between satellites.
The ionosphere over Scandinavia in December 2006 often showed a dense E-layer (100 km height) in early morning hours, which generally disappeared during midday when a dense F-layer (350 km height) was present. On December 14, a strong coronal mass ejection occurred at the Sun, and as a consequence in the ionosphere many intense irregularities appeared, which extended to high altitudes.
More information:
Researcher Max van de Kamp, max.van.de.kamp@fmi.fi
M.M.J.L. van de Kamp: “Medium-scale 4-D Ionospheric Tomography using a Dense GPS Network”, Ann. Geophys., 31, 75–89, doi:10.5194/angeo-31-75-2013, 2013.