KAIRA & Kiitos!

The KAIRA project has been running for some time now and, like most major scientific instruments, there has been a peer-reviewed reference paper produced which describes the facility, its technical capabilities, its scientific goals and the initial results. We have written this paper and it has been accepted by the journal IEEE Transactions on Geoscience and Remote Sensing.

TITLE:     KAIRA: the Kilpisjärvi Atmospheric Imaging Receiver Array -- system overview and first results

ABSTRACT:  The Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) is a dual array of omnidirectional VHF radio antennas located near Kilpisjärvi, Finland. It is operated by the Sodankylä Geophysical Observatory. It makes extensive use of the proven LOFAR antenna and digital signal-processing hardware, and can act as a stand-alone passive receiver, as a receiver for the European Incoherent Scatter (EISCAT) very high frequency (VHF) incoherent scatter radar in Tromsø, or for use in conjunction with other Fenno-Scandinavian VHF experiments. In addition to being a powerful observing instrument in its own right, KAIRA will act as a pathfinder for technologies to be used in the planned EISCAT_3D phased-array incoherent scatter radar system and participate in very long baseline interferometry experiments. This paper gives an overview of KAIRA, its principal hardware and software components, and its main science objectives. We demonstrate the applicability of the radio astronomy technology to our geoscience application. Furthermore, we present a selection of results from the commissioning phase of this new radio observatory.

DOI: 10.1109/TGRS.2014.2342252

With the publication of this paper, we regard the build and commissioning phase of the KAIRA facility as being complete. As a result, the time has come to close the KAIRA web log, which was written for the purposes of reporting on the build of the instrument. The first post was written on Wednesday 30-Jun-2010 and, today Friday 12-Sep-12104, we have the last.

To all our readers over the years, thank you so much for your support, comments and attention. It has been great fun writing for you and, as our web counters indicate, it has been very popular. We have covered so many topics, ranging from the technical, to the tragic, to the humerous, and the downright bizarre. And, it has been a tough project, with real blood, sweat and tears. Yet, it has all been worth it.

Even though this web log will now halt, it will remain in place for future reference. For those who still want to read about KAIRA, Sodankylä Geophysical Observatory, and Arctic Finland, the story continues on the SGO web log.


However, we will now close here with thanks. In Finnish, of course...

Kiitos!

EISCAT_3D Preparatory Phase

This week, we have the last general meeting of the preparatory phase for EISCAT_3D. This project is the next-generation incoherent scatter radar, which will be built in northern Fenno-Scandinavia and, perhaps, beyond. It is an ambitious project, which involved many participants from multiple countries. And, as this particular phase of the project is completed, we are meeting at the Space Physics Institute in Kiruna, Sweden, to discuss the work done, report on the progress made and make plans for the future of this important scientific instrument.

KAIRA has been heavily involved in the project. Although a large multi-purpose facility, capable of carrying out multiple receive-type experiments, it has been used specifically to test certain aspects of the EISCAT_3D proposal. Its deployment garnered useful experience in practical matters regarding the development of a new site and the utilisation and integration of commercially available components within the context of Arctic location and cross-disciplinary application. We have also used KAIRA for new signal processing techniques, such as allowing the lag-profile inversion, and thus accomplishing multibeam, remote-location reception of the EISCAT VHF transmitter signal. This is a critically important step in the construction and operation of \EISCAT for multi-beam, multi-static incoherent scatter radar, and thus true 3D volumetric ionospheric measurement. The KAIRA facility remains operational for on-going EISCAT development and prototyping endeavours.

Undoubtedly, KAIRA will continue to be involved in EISCAT work, and specifically the EISCAT_3D developments. But as this particular part of the project is accomplished, we want to note our involvement and wish the EISCAT Scientific Association all the best for their future goals.

Replacement parts

We've just had some parts arrive from ASTRON. The timing distribution boards are being replaced and so we had three arrive in a box from Dwingeloo. The "Fragile Glass" label on the box got us excited for a moment, but even without any bottles therein, the arrival of new electronics is cool! These will be installed on our next trip to the site and the recovered old boards will be sent back to ASTRON.

New electronics boards from ASTRON (Photo: D. McKay-Bukowski)

University visit

Last week a couple of us from SGO visited the main university campus in Oulu. As most of our readers will know, KAIRA is operated by Sodankylä Geophysical Observatory, which in turn is part of the University of Oulu. it is quite a long way from Kilpisjärvi to Oulu, but that's where we were last week and have a photograph of the towers of learning to share.

University of Oulu (Photo: D. McKay-Bukowski)

Sodankylä Geophysical Observatory blog

There is a new web log. At the end of August, Sodankylä Geophysical Observatory general web log was started. It is being led by established KAIRA author Lassi Roininen and will feature others from the observatory, much more generally than what we have done here. The new site continues along the same path as our KAIRA web log, but the idea is to cover more widely the Observatory activities, including published papers, conference and workshop announcements, reporting on campaigns and extensive research visits, installation of new instruments etc.. Posts will be mostly in English, but with occasional content in Finnish and other languages too. We will also use this new web log for reporting sudden onset events. Naturally, there will also have been some more casual matters from time to time, including anecdotes about life at Sodankylä Geophysical Observatory, the University of Oulu and various other things that form the Lapland experience in Arctic Finland.

So, for all regular readers here, do go an check the new SGO we blog at: blog.sgo.fi

IRIS - Imaging Riometer for Ionospheric Studies

IRIS is an imaging riometer, located at Kilpisjärvi, not too far from KAIRA. It is a single-frequency riometer and images the ionospheric absorption using fixed multibeams (unlike KAIRA which uses both fixed and tracking beams, as well as interferometry). The IRIS beams are formed using Butler matrices.IRIS is operated by the University of Lancaster, UK, with assistance from SGO. It is quite an old instrument and has been operating since September 1994. Its receiver frequency is 38.2 MHz. KAIRA often runs experiments at similar frequencies (for us, subband 195) in order to carry out comparative experiments.

IRIS (Photo: D. McKay-Bukowski)

Applied Inverse Problems 2015

A major inverse problems conference, Applied Inverse Problems, will be organised in Helsinki, Finland, May 25-29, 2015. The event website is at http://aip2015.fips.fi. Important dates are:

• Mini-symposium Proposal Deadline: September 30, 2014

• Poster, Contributed Talk, and Minisymposium Talk Abstract Deadline: November 30, 2014

• Calderon Prize Nomination Deadline: January 31, 2015

• Early Bird Registration Deadline: February 11, 2015

LBA repairs

Well, as reported, the jänis had struck twice and that meant lots of repair work for us. Actually in total there were 14 x LBA aerials to fix.

Status on 27-Aig-2014

The storm damaged ones were the most work. There required fitting new connectors (the old ones had been ripped clean off during the impacts). The jänis-attacked LBAs were more numerous, but less time consuming.

Repaired LBA line (Photo: D. McKay-Bukowski)

The fix was adding a new length of nylon guy line. A double-fisherman's bend is used to join the new section of line to the old and a bowline is used to make the loop to hook over the peg.

To discourage the jänis from simply biting through these again, we smeared the lines with a combination of spray lubricant and grease. This is waterproof and should give a bad smell and texture, thus deterring further jänis attacks.

However, in the long-term, we'll still need to work out a better way of protecting the LBA aerial lines.

Jänis attacks!

Last week we made a service visit to KAIRA. There were four LBA aerials still down from the blizzard of 2014 and these needed fixing. However, on arrival at the site, we noted that there were some other LBA aerials down.

What?!

We hadn't noticed this in the data, so it must have been recent. And inspection of the field indicated that the nylon lines had been cut on multiple LBA aerials, which is what had caused them to fall.

A cut LBA line. (Photo: D. McKay-Bukowski)

Field of woe. (Photo: D. McKay-Bukowski)

We believe that the cause of this is a jänis (Wikipedia). These creatures like to gnaw on things and it looks like the LBA array was the target. Knowing our luck, it was probably the cute jänis we saw a while back.


What's worse, on the second day, we found yet more LBA aerials down. The jänis had struck again! (This led to much silliness on twitter.)

In total, some 10 LBAs were downed over two days (26-27 Aug 2014). More repair work for us then.

KAIRA spectral riometry paper out!

I'm happy to announce that our proof-of-concept study on the electron density profile estimation based on the KAIRA spectral riometry measurement has been finally published in the Geophysical Research Letters, please have a look:

Kero, A., J. Vierinen, D. McKay-Bukowski, C.-F. Enell, M. Sinor, L. Roininen, and Y. Ogawa (2014), Ionospheric electron density profiles inverted from a spectral riometer measurement, Geophys. Res. Lett., 41,  doi:10.1002/2014GL060986

By comparing our spectral riometry results to a simultaneous EISCAT VHF measurement, we were able to show that the methodology works, at least under conditions of relatively strong ionisation. This builds confidence towards continuous monitoring of height-dependent D-region ionisation by spectral riometry.

Typical KAIRA

Today's photo has a bit of everything. The LOFAR HBA tiles, the LBA array in the background, Saana dominating the horizon, the storage containers and site area, and our trusty observatory vehicle.

The KAIRA site (Photo: D. McKay-Bukowski)

Valhalla

Always curious to try local produce, I tried this herb liqueur by Koskenkorva. It comes in a matt black bottle, rates at 35% and is ominously titled:  "Valhalla".

Herb ingredients are: Angelica achangelica, Artemisia absinthium, Achillea millefoium, and Glycyrrhiza glabra. 

Roadworks

Driving back late one night from KAIRA to SGO there was (yet another) hold up. This time roadworks. In fact there is a bridge under repair on the route from Kittila to Sodankylä and this is where we got stuck.

We were the only car.

And yet the delay was... well...

Plasma lines at Arecibo

25 MHz wide plasma line profile at Arecibo, 2.5 seconds of integration. 

A while ago, Thomas covered the Arecibo radar school (you can see our black rack receiver on the table in one his pictures). During the school, a little bit of data taking took place. Between his lectures, Phil Erickson ran data collection with our 25 MHz digital receiver, in anticipation for a longer campaign that will occur later this year. As I wasn't in Puerto Rico, and I've been traveling elsewhere, I'm only now starting to analyze the results. But they are quite nice.  The system can pretty much do what the existing 5 MHz wide Pentek system can do, but at 25 MHz bandwidth, allowing us to measure plasma line profiles such as this. You'll probably need to zoom in the picture to pick out the narrow plasma line. There is also a higher resolution version on line here.

Anyway, this is quite a successful first try. The IF will need to be at a different frequency than 260 (e.g., 264 would be nice), as plasma line below 10 MHz folds, and can also be seen "sliding" down from +12.5 MHz too. Another option is to bring a tuner to shift the band to a lower IF. Also, the wide band IF doesn't seem to be wide enough. The upshifted line isn't that visible due to filter roll-off. 

Data extraction

There are numerous computers in the RF-container, which handle data processing, control and storage. One of these has now been taken out and has been moved back to SGO for use there in some of our interferometric riometry development work. During the extraction of this data system, we had the side cover of the RF-container signal processing racks off, thus once can see the other computers, network gear, etc.

KAIRA data systems (Photo: D. McKay-Bukowski)

Missing in action

Today's photograph shows the frameset of HBA tile #75. Or, we should say... the former HBA tile #75. It is missing due to a severe blizzard that swept through the site at the beginning of the year. We are still waiting for a quote from ASTRON to get this replaced.

Frameset for HBA tile #75 (D. McKay-Bukowski)

A big blade

heading back from KAIRA to SGO the other morning, I was held up for a considerable period of time at the turn to Meltaus. The reason for this was that a convoy was moving three huge blades of a wind turbine and the first of these was starting to make the turn just as I arrived at that point.

It was quite a long wait as the turn was very difficult given the huge length of the blades. I tried to estimate the length and I suspect they are 40-50 metres long each.

Turning wind turbine blades. (Photo: D. McKay-Bukowski)

Information about the project can be found here: http://www.laatumaa.fi/tuulivoima/joukhaisselka-sodankyla/

Arctic green

At this time of year, the Kilpisjärvi region is pretty green. Most of the snow has melted and the trees are not quite yet changing to brown for the autumnal drop. Today's photograph was taken looking south along the western bank of the mound on which the antennas are located. The mountain on the left edge is Saana and on the right is Pikku Malla.

Looking south from KAIRA (Photo: D. McKay-Bukowski)

LBA aerials

KAIRA has 48 low-band antenna (LBA) aerials. These were designed by ASTRON (the Netherlands Foundation for Radio Astronomy). The arrangement of the aerials looks pretty random, but in actual fact it has been carefully chosen to give a good beam-pattern for the radio telescope. Each aerial comprises a steel grid which acts as a ground plane for the aerial. The post is PVC (starting to fade in places due to UV-light exposure) and the black cap at the top contains the low-noise amplifiers (LNAs) - one for each polarisation.

The wires that extend from the cap to the corners of the ground planes are the antenna wires. The form crossed inverted-V dipoles, giving good all-sky sensitivity. Actually the wire part only goes about halfway down. The lower part is either nylon line or elastic, which is used to hold the aerial in place.

Low-Band Antenna (LBA) at KAIRA. (Photo: D. McKay-Bukowski)

Ounas River

Today's photograph is dawn, seen over the Ounas River, not far from Kittila.

Ounas River, Lapland, Finland.