2013 ISR school (MIT, Haystack)

This week, there is the 2013 Incoherent Scatter Radar school being held at MIT Haystack Observatory. Sodankylä Geophysical Observatory will have a lecturer there and we can expect reports on the EISCAT_3D weblog during the week.

That flat cap. I've seen that before somewhere... (Photo: Th.Ulich)

The fate of the mushrooms

You may recall from the other day that we had been out in the forest hunting for mushrooms. In then end (with the help of a local expert) we identified and picked some. So... what became of these woodland delicacies?

Pizza!

Strange RFI

Occasionally we come across some strange signals in the data. About a week ago, I was processing some RCU mode 6 data and was checking the received power as a function of beamlet. Because the beamlets were all at the same pointing direction, and had been mapped linearly with subband, there would be an expected slope from high to low with the increase in beamlet number. That is mostly what we got.

However, the puzzling thing was the presence of a pair of "ridges" in the slope. It looked like there were two bands of increased power. They were only sometimes present too. However a 2D plot showed mroe clearly what was going on.

The above plot shows the beamlets plotted against time. The equivalent frequencies are shown on the right-hand side. The time axis is in samples (where 1 sample = 1 second, in these data). The darker the colour, the more radio power is being received.

Just below 227 MHz there is some single-subband RFI. Also, at some times there are broadband (= all frequency) bursts, around sample 3230 and 3745 for instance.

However, the two blocks of RFI that caught my attention in the first place a quite strange. They have a broad, but still finite in bandwidth. They are non continuous. Also, there is a hint of dispersion in some of them. Also, they are broadcasting to two distinct blocks of frequencies, rather than a single range.

We're not sure just yet what they are, but with luck we might be able to catch one with raw voltage recording. Certainly if anyone has any ideas, send and e-mail or leave a note in the comments section below.

Arctic mushrooms

Today we have some more photographs from our recent trek through the forest. This time it is the mushrooms! Fort the trip, I went with a local expert, who could recognise the safe from the dangerous ones. The only thing is... I don't know (or don't remember) what any of them were called.

Polar mesospheric summer echoes

This week, we've been supporting EISCAT observations of polar mesospheric summer echoes (PMSE). These are unusually strong VHF radar reflections ("echoes") that occur at around 80-85 km altitude (hence "mesospheric"). This is the altitude of what is called the "D-Region" of the ionosphere, and it is a similar altitude to that where noctilucent clouds are found. They are noted at high latitudes ("polar") from June to August in the north (thus "summer").

PMSE are not well understood and remain an area of active research. The campaign that is currently running is making use of multiple facilities in Norway, Sweden and Finland, and KAIRA is playing its role, observing the radar echoes from the EISCAT VHF using a multibeam experiment. In total 60 HBA beamlets (20 pointing directions x 3 subbands each) are being recorded, at raw signal levels using our local pipeline programme (KLP).

We hope that the additional spatial information provided by KAIRA will assist the scientists who are researching this phenomenon. Hopefully, we'll be able to report some successful results soon.

Site-eye commemorate the official opening of KAIRA

Site-Eye (the company which has been making documentaries and 3D-films about KAIRA have posted a link with the film they made of the official opening of KAIRA. They write:

Never without a camera, or an excuse to use it, Site-Eye Director Brian McClave shot this time-lapse footage during the official opening ceremony of the KAIRA project.The event which took place at the facility in Northern Finland lit by the 24 hour sunshine of summer in the Arctic Circle formally opened the site of the hybrid radio telescope, radar receiver and atmospheric research station.

With the ribbon cut by Lauri Lajunen, Rector of Oulu University, one of KAIRA’s main sponsors, the party of specially invited journalists and scientists then proceeded to the local school hall for a special premier screening of Site-Eye’s ‘KAIRA’ documentary.

The documentary which features interviews with the figures prominent in the building and running of the KAIRA project was shot by Brian and oft-collaborator Gavin Peacock on location in the arctic tundra last year. Including spectacular footage of radar dishes, arctic wilderness and the Aurora Borealis by night, "KAIRA" the Site-Eye made documentary was screened in both 2D and 3D and was rapturously received by the assembled audience. It is next due for an even bigger screening in September. "93 Million Miles" a short film produced from the same material has already gone on to win international awards.
After the screening, in true Finnish tradition many of the party indulged with a swim in the lake followed by a hot sauna, although Brian, put off by the icy lake temperatures and swarms of mosquitos refutes that he took part in any of these festivities.

Have a nice weekend everyone!

Link: http://vimeo.com/71085432

Cottongrass

Today we're back to the flora that surrounds the Sodankylä Geophysical Observatory (SGO) area. Across the road from the SGO entrance, there is a large swamp area, where the Finnish Meteorological Institute (FMI, also based at Tähtelä) have a number of measurement instruments. And, during our recent walk through the area, we took a few photographs of some of the flora in this swamp region. The photographs shown here are of cottongrass.

Cottongrass (Finnish = Tupasvilla, Latin = Eriophorum vaginatum)

A close-up of the wispy cotton at the head of the stem.

SyncOptic repeater unit arrives

We've just received delivery of a new SyncOptic repeater unit from ASTRON. This is a LOFAR upgrade to improve timing on the stations and remove the occurrence of 5ns jumps which existed with the old clock distribution system.

SyncOptic repeater unit (Photo: D. McKay-Bukowski)

This new unit is now at SGO and will be taken up to KAIRA for installation soon.

Reindeer lichen

Continuing with our Arctic botany theme this week, today's photograph is of "reindeer lichen" (also known as "reindeer moss"). This lichen is a pale whitish-grey and covers huge areas of the forest with a ghostly, spongy carpet.

Reindeer lichen (Finnish = Poronjäkälä, Latin = Cladonia rangiferina)

It is a source of food for the reindeer and this is clearly seen by the fact that it is prominent in the areas that are fenced off to stop the reindeer from getting in. In fact, it is just as well there are some protected areas around the observatory (although our motivation is to protect the equipment), as the reindeer would otherwise totally overgraze the lichen (which is very slow growing and takes many years to establish tick ground cover like that shown here.

This reindeer fence marks the edge of the lichen carpet

PS:  Oh, and we should point out that all the photographs this week are from around the area near Sodankylä Geophysical Observatory (SGO, Tähtelä) which is where the researchers work. This is an Arctic boreal climate, which is somewhat different from the area where KAIRA itself is.

The berries of Arctic summer

As we mentioned in yesterday's post, we'll be reporting on our forest expedition in the area around the Tähtelä area. Today, there are some of the edible berries that we found on the expedition.

Crowberry (Finnish = Variksenmarja, Latin = Empetrum nigrum)

Bilberry (Finnish = mustikka, Latin = Vaccinium myrtillus)

Cloudberry (Finnish = lakka, Latin = Rubus chamaemorus)

Forest trail

With warn (approx 10-15 deg C) weather and the rain holding off, today we went for a walk along some of the forest trails around the institute. The purpose of the mission... to hunt for the first mushrooms of the season.

One of the forest trails near SGO. (Photo: D. McKay-Bukowski)

We'll post up some of the finds that we made of the next few days, interspersing them with our more serious topics of astrophysics, atmospheric physics and instrumentation.

Gaussian Markov random fields and Donald Duck

Gaussian Markov random fields (GMRF) are a powerful tool for making a priori distributions for Bayesian inversion. By suitable parameterisation via latent variables, we can describe a big number of features, for example ionospheric structures. In order to demonstrate the flexibility of  GMRFs, below is the Random Duck demonstration done by drawing random samples of a certain GMRF with varying correlation structure.

For more details on Gaussian Markov random fields, see for example correlation priors paper (Roininen et al. 2011).

This one needs a caption

Friday again (what? again?! so soon?!!) and so it is time for a photograph. After posting a rather serious no-photo article last week, we've decided to put up something a bit more light-hearted. So, browsing through the recent shots, we stumbled across this one that fits the bill rather nicely.

The photograph was taken by the SGO Director, Esa Turunen on the day of the official KAIRA opening in early June. However, it definitely needs a caption! Feel free to post suggestions in the comments below.  :-)

And have a nice weekend everyone!

TomoScand: Regional ionospheric multi-instrument tomography in Fennoscandia

Finnish Meteorological Institute in collaboration with Sodankylä Geophysical Observatory (and especially Kaira team) are developing a 3D ionospheric tomography instrument. The project is called TomoScand. Below is a poster presenting several TomoScand project deliverables. The poster was presented in the 2013 Beacon Satellite Symposium (Bath, UK, 8-12 July 2013).

The challenge of calibrating

Calibration can be tricky business. Especially when you get interesting scientific events occurring during the calibration process. Recently, we were attempting to measure the on/off source fluxes to estimate KAIRA's sensitivity. Two problems crept in: ionospheric scintillation and ionospheric opacity.

In the plot, the vertical axis is labelled "beamlet number", but it is linearly-proportional to frequency. The horizontal axis is time. Red is strong radio emission and blue is very weak. The two main blocks in the middle of the plot are Cygnus A and Cassiopeia A.

If you look at the top of them (around beamlets 320-400), you can see a "colourful fringe". This is ionospheric scintillation. We know about this and the solution is to time-average to smear it out.

However at the lower frequencies (roughly beamlets 50-130) there are also some odd effects. In particular, around samples 7000-8000 there is a large drop in radio strength from Cygnus A. This is caused by increasing electron density in the ionosphere (around 80km up).

In this plot it is pretty obvious, but it certainly caused us to puzzle over the rather odd results when we were trying to figure out why the Cygnus A measurements gave such completely different ones to the Cassiopeia A equivalent.

Summer storms... the data

Still on the theme of cooler weather, a while ago we posted a few photographs of some of the summer storms. Well, as we've been trawling through the data, we've found that particular event, and it looks pretty interesting in radio part of the spectrum.

In the first plot we have the different beamlets plotted as a function of time. The colours indicate the power (blues = low power, greens = medium, reds = strong).

Power (colour) for beamlets vs time.

The horizontal bands are for the different pointing directions (we have 11-14 beamlets per direction). Small rises in power (such as the green-ish section on the left) are due to parts of our Galaxy passing through those particular beams. The small flecks (such as in beamlets 85-95) are ionospheric scintillation.

But the interesting part here are the thin (single-sample) vertical lines that run through all beamlets. These are the radio bursts from the nearby lightning.

If we take the mean of all beamlets in the above plot and put them on the same time-axis, we see a rather startling forest of lightning discharge events.

Mean of beamlets from Plot 1 on the same time axis.

What's more, the above plot has a logarithmic vertical axis, giving some idea of the power levels that we get from these nearby atmospheric events.

Returning to the cool north

Having been away from Sodankylä Geophysical Observatory (SGO) for the past few weeks for meetings and conferences, it has been bliss to return to the cool north. My last port of call had been the United Kingdom, which had been suffering something of a heatwave. Where I was, the temperature made it into the low 30s (celsius). While that might not be hot for some, or lovely and warm for others, it is certainly too hot for me. Far too hot.

So it has been lovely to return to the Arctic and find beautiful grey skies, light rain and (to my tastes) what is a pleasant temperature (10-15 ^oC). So, today's image is from the real-time temperature monitor at the SGO institute.

My idea of warm weather.

The real-time data are available online from: http://www.sgo.fi/Data/RealTime/temperature.php


PS:  Apparently there was a light snow-fall at Kilpisjärvi last week... and I missed it!  :-(

Freeze frame

On the right hand side of this web log there is an all-sky image. It is always the latest image that was taken with KAIRA, updated every minute or so in order to always be up-to-date. Apart from being an interesting curiosity, it is useful for the researchers, as it lets us keep tabs on the data flow and notice if something stops. But it also lets us monitor the radio sky for interesting events, whether an active Sun or pesky radio-frequency interference (RFI).

However, some you may have noticed that it hasn't updated recently. It is still set at this image, taken on the evening of the 9th July 2013.

The last "regular" all-sky image... at least for a little while, while we complete the
visualisation software for the new correlator mode that we are now running.

The reason for the stop at this point has nothing to do with a failure of the system. In fact, KAIRA is still working; still observing 24-hours a day. What has happened is that we have changed our correlator mode.

At KAIRA, we are always experimenting with new and interesting ways of using the LOFAR technology. From the now-popular 357 mode, through to wide bandwidth low-bit observing, we pride ourselves in the novel usage of the system to visualise and discover new things about the natural universe.

Currently, we are at it again. This time we're experimenting with a new station correlator configuration. This will allow us to carry out a different type of radio astronomy observation, and it will also be useful for our ionospheric scintillation work too. And while the data system is working fine, we haven't yet written the software to convert this new visibility data into an online image. Yes, we'll get there, but it is going to take a little while.

So, given that we switched on the new correlator mode on 09-Jul-2013 at 23:00 UTC, the above image is the most recent processed image we have.

Updates to follow soon!

Malla nearly snow free

Just a site photograph today, taken a few weeks ago by one of the SGO researchers on his way up to Tromsø. As you can see the snow is now mostly gone on the mountains (the site itself has been clear for about a month).

KAIRA site (2012-06-24; Photo: L. Roininen)

No Friday Photograph

For anyone who writes a web log, or at least tries to do so regularly, you will know that it is a lot of work. Sure, the first few weeks are easy, as there are lots of ideas. And when it is busy, that is also pretty straight forward... assuming you can find a spare moment to upload all the interesting material!

However, then there are the quieter times. During summer vacations. And during long stretches of routine observing, with no site visits, no interesting results, and that plot you were preparing still needs more work (yes, it really does need more work). It is at these times that the web log is tough going. Here at KAIRA, we've been trying to keep a average of five posts a week ever since we've been operational. This has been easy at some times, especially during the build, but just now... hmm... difficult.

So as I was trawling through photographs looking for something (anything!) to post today, it occurred to me that perhaps I should write about something for which there is no photograph.

The other day, I caught a programme about the Secret Life of the Sun. It was a documentary about the Sun, its energy processes and how they affect the Earth. It was an interesting programme, but one thing that caught my attention was when one of the presenters was describing a total solar eclipse. This, of course, is when the Sun's disc is completely covered by the Moon, thus allowing the corona to be seen. For a brief moment, the surroundings are plunged into a special night: the birds sing evensong, the air cools noticably, the shadows sharpen, and then all is dark and the Sun's atmosphere is the only source of illumination. The presented ask how could anyone not be moved by such a spectacle.

Sorry.

I've seen a total solar eclipse. And while I would say it was very nice, and interesting to watch and all, would I call it `moving'? Hmm. No. Not really. Does that mean that I am cold and heartless and untouched by the beauty of the natural world? No. I have seen many moving sights during my time. And the thing that I would call the most moving would be a truly spectacular auroral display.

I've seen a few very good displays, but there was one that really struck at the heart. It was in early 2006 and I was on Svalbard. The EISCAT radar operator, a couple of observers and I were driving back from the radar down to the settlement of Longyearbyen. As we drove along the snowy flats in the polar darkness, the operator (who was driving) slowed down and stopped the vehicle. `It looks like this aurora might be bright', he said. `Shall we take a look?'. Of course we agreed.

For the next 20-30 minutes the sky was set ablaze. The streamers and curtains of blue-green light were vivid, dynamic and full of intricacy. I would almost described them as fractal, in the sense that at the largest scales and the smallest, there was movement, detail and colour. And around the edges, wisps of the most incredible shades of indigo-violet flickered and leapt in keeping with the sweeps and whorls of the main display.

On my eyelashes were frozen tear drops.

No-one said a word, and even after the display had passed and had vanished over the horizon, we all still stood there awestruck. No one said anything for many minutes until, as if by secret cue, we got back into the vehicle without a word and, shivering, we drove the remainder of the way to Longyearbyen in silence.

There are no photographs for this. No photograph has yet captured the dynamic range of an aurora. The movement, the changes in shade and brightness. On a photograph, they are blurred out. There is no context. Even the colours are often wrong, being some parrot green, just because the CCD chips in modern digital cameras cannot cope with pure monochromaticism from the different transitions in the aurora.

Yes, I could drag out some old photograph or find a stock image on the web, but it would not be the same.

Thus, for today, there is no photograph.

On the images indelibly etched in my mind's eye.

Another KAIRA map

There are one or two KAIRA maps floating about, showing the location of the site with respect to other sites, boundaries and towns. Today we feature a rather nice one, by Thomas Ulich. It is a map of northern Fenno-Scandianvia, showing the location of KAIRA. Also plotted are the locations of the EISCAT mainland facilities.

The direct link to the full version can be found here:

http://www.sgo.fi/KAIRA/press/KAIRA_EISCAT_map.png

PROBA2 Guest Investigator Programme

The Fourth Call for PROBA2 Guest Investigator Programme is now open

PROBA2, the technologically advanced ESA micro-satellite studying the Sun, has been in orbit since November 2009 (http://proba2.oma.be). Onboard, both the EUV imager SWAP and the EUV/UV radiometer LYRA have been acquiring unique data for more than three years. During that time, 25 PROBA2 Guest Investigators have visited the PROBA2 Science Center at the Royal Observatory of Belgium, in Brussels, to efficiently use PROBA2 data in their research.

A new Call for Ideas for the PROBA2 Guest Investigator Programme is now open for the period October 2013 and May 2014.

Selected proposers will be invited to spend up to a few months with the PI teams to obtain expert knowledge on the instruments and to participate in the daily operations of SWAP and LYRA. Each guest investigator will be reimbursed for travel, accommodation and living expenses. Additional details about the PROBA2 Guest Investigator programme and application information can be found on the PROBA2 website at:

http://proba2.oma.be/FourthGICall

RF patch cables and RCUs

Just a neat photograph today... this one was taken on the day of the official opening, looking across the patch cables going into the Receiver Unit (RCU) subracks.

RCUs and patch cables at KAIRA (Photo: J. Keskitalo)

The astute LOFAR observer will know that this is either an RCU mode 3 or mode 4 observation. (Because the led above all the middle input connectors is lit.) Indeed, we observed mode 3 riometry throughout that particular day.

The Chilbolton dish

Another photograph from the Observatory at Chilbolton. This time a close-up view of the 25m dish. This system operates as a weather radar and is also used for satellite tracking projects.

The 25m dish at Chilbolton. (Photo: D. McKay-Bukowski)

Wildflowers at UK608

This weekend I made a visit to the LOFAR station in the United Kingdom (UK608, Chilbolton) in order to work on various station calibration things for both KAIRA and LOFAR generally. While there, I went out to the field itself to see the antennas. Being at the height of the British summer (which lasts for 3-4 days on average), there were plenty of wild flowers in bloom, including some near and on the array itself.

Wild poppies near the LBA aerials. In the background is the 25m dish (Photo: D. McKay-Bukowski)

More wildflowers near the aerials. Does anyone know what they are? (Photo: D. McKay-Bukowski)

KAIRA beamlet statistics plotting programme

During the summer months, Sodankylä Geophysical Observatory runs a student/worker programme, which gives an opportunity to youngsters to gain valuable work experience (and earn a bit of money too). One of our summer workers this year, was Taavi Vierinen, who we asked to take on a task of writing some software to merge and plot KAIRA beamlet statistics (BST) files.

Taavi accomplished this task very well and produced an excellent result. He also learned a lot in the process, not just about KAIRA and our geophysics, but also about programming and software engineering techniques. (He also taught us a thing or two!).

Today was Taavi's last day at the observatory. Before departing, he wrote this small report, in addition to the rest of the software documentation, which we are including as today's KAIRA web log post.

Taavi writes about his software:

This program combines two BST files into a single one, the program can also be used to plot an image from a single file. Data taken from the two files is controlled by user input, giving the program time from last N seconds as variable. The program then detects the relevant files and takes copies the data, amount specified by the given time from the chronologically first file, if it doesn't have enough data, the program then continues to second file and copies the remainder from there. If there is no file from the day specified, the program will use file filled with 'scrap data' to create empty data in its place, the scrap data is one hour of information copied from a random BST file repeated 24 times to get 24 hours amount of data. If neither of the two files is found, the program will still plot an image, but it will be fully black graph representing that there is no data from given period.

Sample plots... click to enlarge. (Image: T. Vierinen)

After the temporary file is created, the code made by Derek kicks in and uses the data to create a graph. Only changes I made there were few lines of code that would draw a black box on the scrap data and one that draws a line to position where the data from different files meet, so it is easier to see from which day the data originally came.

In the screenshot there are images which were drawn by the program: reference (1), (2) and (3).

• In reference(1) you can see what is drawn when both of the relevant files are found, if data from only a single file is used, the image will be similar, but it won't have the white line as there is only a single file as its source.
• In reference(2) you can see what the image looks like when the latest file doesn't exist. The program draws black box in its place, for 24 hours worth of samples.
• In reference(3) the situation is reversed from reference(2), this time the oldest of the two wanted files doesn't exist, note that in both reference(2) and reference(3), the white line separating the data from different source can be seen.

The program was created using python 2.7.5, by both me, Taavi Vierinen, and Derek McKay-Bukowski. I enjoyed this project, because I managed to learn a lot of skills from it, from using python to managing what I did on my spare time. The project was good to me in many ways and it wasn't too easy either, nor too difficult!

-Taavi Vierinen

Thanks for all your efforts Taavi and well done on the project. Have a safe trip back down south and we wish you all the best.

To you, and all our readers, have a nice weekend!

The LOFAR logo

We all know the LOFAR logo...

But who remembers the old one? There used to be an old logo that was used for the LOFAR project. In fact, it can still be found in a few places. And one of these are the front panels of the receiver units.

This photograph is a close-up of one of those in the RF-container of KAIRA.

Close-up of the KAIRA RCU subrack (Photo: J. Keskitalo)

ASTRON JIVE daily image

KAIRA has yet again featured on the ASTRON/JIVE daily image. Yesterday, a montage of the official opening was shown, along with a description of the event and thanks to all our friends (especially those from LOFAR/ASTRON who have helped make the project a success so far.

The ASTRON/JIVE daily image provides an update every weekday with highlights related to our field of radio astronomy and the work of ASTRON, JIVE, LOFAR and other related projects. KAIRA has now featured four times on the site:

• 14-Jul-2011
• 20-Jul-2011
• 23-Feb-2012
• 02-Jul-2013.

Note you can also follow the daily image on Twitter: @daily_image

Link:  http://www.astron.nl/dailyimage/index.html?main.php?date=20130702

SpacePy

SpacePy is a package for Python specifically for those working in the space sciences. It provides a set of tools which build on the well-established NumPy and MatPlotLib packages, to make data analysis, modelling and visualisation easier. The project web site lists the following benefits of this toolkit:

• Quickly obtain data
• Create publications quality plots
• Perform complicated analysis easily
• Run common empirical models
• Change coordinates effortlessly
• Harness the power of Python

To quote further from the SpacePy website:

"The SpacePy project seeks to promote accurate and open research standards by providing an open environment for code development. In the space physics community there has long been a significant reliance on proprietary languages that restrict free transfer of data and reproducibility of results. By providing a comprehensive, open-source library of widely-used analysis and visualization tools in a free, modern and intuitive language, we hope that this reliance will be diminished."

More details are available from the SpacePy website at:  http://spacepy.lanl.gov/

Multi-lingual

We start the week with a photograph of the KAIRA information sign. It was put up on the side of the HBA for the official opening, but will later be moved so that the public can easily view it. It has a short description of the project... in six languages!

The KAIRA information sign. (Photo: D. McKay-Bukowski)

The languages are: Finnish, Sami, Swedish, Norwegian, German and English.