EISCAT Campaign in Tromsø

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

Incoherent Scatter Radar School: Student Presentations and Conclusions

Today was the high point of our incoherent scatter radar (ISR) school, as it was the students' turn to give presentations, while lecturers would listen and ask questions. The 7 groups had half an hour each to present the results of their radar experiments, explaining their scientific motivations and experiment designs, describing the data they had obtained, and discussing on their interpretation.

The talks were really high-level ones; everybody had put a great effort into the task and played the game. Even when the initial scientific targets could not be reached – because of technical problems or too quiet ionospheric conditions – the students managed to come up with a plan B and did a great job in analysing their data sets.

Group 3 studied the polar cap convection with an ESR experiment.
Photo: M. Lavarra

Among the observed phenomena, we had beautiful polar mesospheric summer echoes, electron precipitation, polar cap convection, auroral arcs... And ISR observations were confirmed by measurements from other instruments: ionosonde, SuperDARN, GPS TEC data, satellite observations... 

After closing discussions, it was already time to say goodbye. Most participants are now on their way to Helsinki, spending the night on the train. Hopefully students and lecturers have had a great time in Sodankylä and got to know new potential future collaborators/friends. So, the ISR school is now over... until next time!

Incoherent Scatter Radar School: Analysing Experiment Data

As the end of the radar school is already approaching, a greater and greater part of the programme is dedicated to group work. Yesterday, the morning lectures were essentially focusing on analysing the incoherent scatter radar (ISR) data and fitting the ISR spectrum to extract ionospheric parameters. Other lectures had a more scientific focus and showed examples of ionospheric phenomena which can be studied with ISRs. One more lecture aimed at underlining the importance of keeping a critical view on the analysed data before drawing scientific conclusions.

In the afternoon, the group work on the analysis of Tuesday night's data was continued. Most groups managed to come up with a clear plan on how to divide tasks, which features in the data to focus on, and which additional data sets to look at.

Group 5 looking for particle precipitation signatures in their data.
Photo: C. Heinselman

This all looks very promising for the presentations of Saturday morning. It seems that each group have their own scientific focus, which makes it all the more interesting. Let's see how far they manage to get by this evening!

Incoherent Scatter Radar School: Experiment Night

One of the highlights of the Radar School is the experiment night, which took place yesterday. The participants were divided into groups of 5 to 6 people and had to design a radar experiment to be run using EISCAT.

After the morning lectures providing students with some background on the incoherent scatter theory, pulse coding and experiment configuration, each group was asked to come up with a scientific focus related to the ionosphere (study of a particular region, feature, or process). Based on their topic of interest, they had then to discuss what kind of trade-off they could reach in order to obtain the best possible data. Which altitude and latitude do they want to observe? Is there a preferred magnetic local time for the features they are interested in? What time and range resolution do they need? Is there an optimal pointing direction or scanning pattern in their case?

Once the group agreed on the answers to those questions, they could write a proposal of experiment for either the EISCAT mainland VHF radar or the EISCAT Svalbard Radar (ESR), and request a 2-hour time slot between 17:30 and 01:30 local time. The proposal needed to mention which experiment code should be run, and the desired pointing direction. All those details were submitted to the lecturers, who evaluated them and notified acceptance within 10 minutes, to start with the first experiment less than 30 minutes later (as someone pointed out, this is a once-in-a-lifetime situation!).

Monitoring the polar cap convection with ESR.
Photo: E. Turunen

The experiments were run from the lecture hall of the Polaria building in SGO, by the students themselves, under the supervision of lecturers with experience as EISCAT users. The experiment time slots were intertwined with "radar walks" around Tähtelä, during which the main on-site instruments were briefly presented (and local mosquitoes were properly fed).

During one of the "radar walks" at SGO.
Photo: C. Heinselman

For the rest of the week, participants will retrieve and analyse their data. More on that in the coming days!

An EISCAT cake at the Northernmost Baking Competition

Last Sunday, a group of students at the University Centre in Svalbard (UNIS) organised a baking competition – which they assumed to be the northernmost one, with rather high chances of being right. Fifteen teams came up with their masterpieces, competing in three different categories: best taste, best design/creativity and unexpected ingredient.

It must be said that the level was pretty high, and the event attracted about seventy students to the third-floor kitchen of the Sjøskrenten student housing to be judges and vote for their favourite cakes after conscientious tasting.

The ESR cake, by the Collisional Quenchers

The Arctic Geophysics Master and PhD students, aka the Collisional Quenchers, proudly managed to get to the third place in the best design/creativity category! Their EISCAT Svalbard Radar (ESR) cake indeed made a great impression on the audience, although this could not compete with the very professional-looking Russian Mine Cake, by far ranking first. Had there been a nerdy category in the competition, though, they would surely have won!

The Russian Mine Cake, winner in the best design/creativity category

Seeking for NEIALs with the EISCAT radars

Last night, an atypical incoherent scatter radar experiment was run in parallel at the EISCAT radars on Svalbard (ESR) and in Tromsø. Dr Anja Strømme, from Stanford Research Institute (SRI) International, is indeed conducting an ambitious project. She offered some of the students following the radar course at UNIS (the University Centre in Svalbard) – for which she is giving lectures these weeks – to join her at ESR while the radars were running.

The objective of her project is to study the NEIALs, the acronym for Naturally-Enhanced Ion Acoustic Lines, which appear regularly on the incoherent scatter radar (ISR) spectra. These features show as a strong enhancement of one (or both) of the lobes of the double-humped ISR spectrum for a short time. The underlying mechanism leading to such observations is still not well understood, and several tentatives of explanation are competing.

A potential NEIAL signature in the ISR spectrum (pink blob in the middle-right-hand panel) observed at ESR.
Figure: EISCAT Scientific Association.

To try to improve the understanding of this phenomenon, Anja ran a very specific experiment, getting the radar to a non-nominal mode. The idea is to have the radar in Tromsø observe along the magnetic field line, while the ESR points in such a way that its line of sight is tangential to the field line observed by the Tromsø radar, in the so-called acceleration region. The two radar beams cross at a distance of about 6000 km, way outside of the ionosphere. At that distance, the plasma density is extremely low, giving incredibly weak backscattered signal, which is why the experiment is so ambitious. The aim is to observe whether NEIALs can be observed simultaneously with both radars, which would support the hypothesis that they originate from the acceleration region.

If these observations prove successful, no doubt that this will lead to very exciting science. Stay tuned for publications!

Successful ICI-4 rocket launch during fieldwork at ESR

Lucky again! The Master and PhD students in Arctic Geophysics at the University Centre in Svalbard (UNIS) are this time spending the week at the EISCAT on Svalbard Radar (ESR). They are allocated two hours of radar time per pair of students to run the experiments they designed during the previous weeks to study substorms, polar cap patches, auroral structures and ion outflows. If Tuesday night was the opportunity to take group pictures in front of the ESR dishes with the aurora in the background, last night was a really special one.

It reads "UNIS" (of course).
Photo: M. Grandin

Indeed, as the weather conditions were quite promising, we were informed upon our arrival at ESR that the ICI-4 rocket was likely to be launched from Andøya (mainland Norway) that very night. The ICI-4 mission, led by Pr Jøran Moen from the University of Oslo, is aimed at studying the interaction of an electron cloud with an auroral arc. The electron cloud in question is the result of the drifting of a polar cap patch to auroral latitudes. Since such a configuration generates high disturbances on radio signals, it is a topic of great interest, and in-situ measurements of the physical phenomena occurring within this structure therefore prove extremely valuable.

There was a lot of suspense regarding the possibility to have at the same time favourable weather and geophysical conditions, and both from Andøya and ESR we were all monitoring in real time the ionospheric measurements made by EISCAT and the Norwegian magnetometer chain. Finally, as the optimal conditions appeared, it was decided to launch ICI-4. The final countdown ended at 23:06 local time (22:06 UT), and we all followed the mission elapsed time count for about ten minutes after the take-off.

Happiness at ESR after the successful launch.
Photo: A. Hall

After such a thrilling fieldwork evening, let us wish to Jøran Moen and all the people involved in ICI-4 that the rocket recorded great data for them to study what happens when an electron cloud encounters an auroral arc!