Atmospheric research at Kilpisjärvi — Part 3

Also at Kilpisjärvi, SGO operates an AARDDVARK VLF-receiver next to IRIS antenna field that we described yesterday. The VLF-receiver detects changes in ionisation levels from 30 to 85km altitude in the 11 different propagation paths of VLF-transmitter signals at the frequency band 16.4-37.5 kHz. The Kilpisjärvi receiver is part of the wider receiver network. SGO has another AARDDVARK receiver in Sodankylä.

The AARDDVARK antennas. (Photo: Tero Raita)

One of the ionospheric tomography receivers of SGO is also in Kilpisjärvi. Transmitted beacon signals of the Russian low-earth-orbit satellites are used to calculate tomographic electron density maps of the F-region ionosphere. Currently 250-300 electron density reconstructions per month are processed from the data of five receiver stations across Finland and Sweden.

The tomography antenna (having just been cleared of snow).

It is a little difficult to see, but you should be able to make it
out in the foreground of the image. In the background you
can see the mighty Saana mountain. (Photo: Tero Raita)

Today most of the instruments are located near the Kilpisjärvi biological station, which is administered by the University of Helsinki. The radio instruments running in continuous-operation mode offer valuable long-term scientific datasets. The optical instruments, which only operate at night time are somewhat limited and are generally only being used from October to April due to the nightless summer time in the Arctic.

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That concludes our mini-series on Atmospheric research at Kilpisjärvi. Thanks go to Tero Raita for the articles and photographs.