Time for the traditional Finnish autumn EISCAT campaign! Ilkka Virtanen and I have been running radar experiments since last Friday evening, from the control room of the Ramfjord site near Tromsø, Norway. This is the site where the EISCAT transmitters are located: the VHF – which may be used alongside the Sodankylä and Kiruna receivers for tri-static measurements –, the UHF, and the ionospheric heating system (among other instruments).
Four experiments from the Finnish EISCAT user community were scheduled for this campaign. A first experiment consisted in a continuous 48-hour run of the EISCAT Svalbard Radar (ESR) during a solar wind high-speed stream. It was run in the beginning of this month, separately from the rest of the campaign. The second experiment aimed at using the UHF radar in a 3-position scanning mode to study neutral wind acceleration during auroral activity. The third experiment was supposed to use UHF, VHF, remote VHF receivers, ESR and the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) to cover SWARM satellite overpasses during two nights. The fourth experiment was supposed to study the lower ionosphere during pulsating aurora, using the VHF system.
Unfortunately, as this is often the case, reality reserves some surprises. In our case, these were not particularly good ones, since the KAIRA clock experiences some time drift, probably because its rubidium atomic clock needs to be replaced. Just to make sure that we have no regrets about it, the VHF is also down due to problems with a coaxial cable. As a consequence, the experiments using the VHF system could not be run as planned: the SWARM experiment only used field-aligned UHF measurements and ESR, and the pulsating aurora experiment had to be totally cancelled.
As a form of compensation, we have been granted exceptional weather here in Tromsø – while on the Finnish side of the border, thick clouds offer an uninterrupted display of medium-grey and dark-grey. And at night, the aurora gave us several nice displays during the previous nights. Some form of compensation, indeed.
|The UHF radar, the aurora, and a mysterious beam of light.|
Photo: M. Grandin