Trends 2014 - completed

Trends 2014 meeting was successfully completed. A number of topics were covered. For me personally, the most interesting new information was that the trends affect the space debris population. Hence, we need to follow the foF2 and hmF2 trends... and of course EISCAT and EISCAT_3D space debris measurements are important in this business! Also, bit of Ethiopia news: American colleagues will install two Fabry-Perot interferometers to Ethiopia during the coming autumn!

I presented my own stuff today and talked about dynamic linear models and estimation of time-varying hmF2 trend of the Sodankylä ionosonde data (see Figure below).

Hence, time to travel up to Sodankylä, ETA Friday evening 23 LT! (stopping at London for Th-Fr night)

hmF2 dynamic trend for Sodankylä 1957-2014.

... and presenting my stuff! (photo: Erkki Kyrölä, FMI)

Trends 2014, Cambridge UK, July 28-31

This week, in Cambridge UK, takes place 8th Workshop on Long-Term Changes and Trends in the Atmosphere 2014. The meeting started on Monday morning and will run until Thursday afternoon. I will have my talk on Thursday! As this meeting is not 'inverse problems', i.e. I am out of my comfort zone, so today we will simply feature photos from the conference venue Clare College. (It is absolutely stunning and beautiful college.) I will come back to the science covered later this week (hopefully) !!

Hengenvaara

Last week we went for a bit of a walk to the FMI radar at Luosto. On the way, we passed some little hut... probably an electric power distribution box.

On the door was a sign... "Hengenvaara"

Now, if I understand this correctly:  "vaara" is "hill"... as in Pittiövaara or Lampivaara.

Of course this is not to be confused with "väärä", which would be "incorrect" (and also incorrect).

And "hengen" (as in "henki") is "spirits" or "souls"... or something.

So, does that mean that this hill is haunted? And, if so, by whom?

Well... probably the person who mistranslated the sign and was subsequently electrocuted!

Meet the press

We had a visit from a reporter this week, to interview some of the staff about KAIRA, the Centre of Excellence for Inverse Problems, EISCAT and the general operations of Sodankylä Geophysical Observatory. So, reporting on the reporting, today we have a photograph of just that!

Lassi and Esa being photographed in front of the 32m dish.

Have a nice weekend everyone!

Ionospheric "Scintillation Arcs"

Compact radio sources twinkle (“scintillate”) because of variations in density moving around in the interstellar medium, the solar wind and the Earth's ionosphere, in exactly the same way as the visible stars scintillate due to the Earth's atmosphere. This scintillation has been studied for many years and is used as a way of probing these density variations and gleaning information about, for example, the density and velocity of the solar wind.  With KAIRA we have been observing ionospheric scintillation since operations started in 2012.

When viewed as a time series, the scintillation manifests itself as rapid variations in received intensity. If the received signal is also split up into a number of frequency channels across the available bandwidth, the time series' for each channel can be stacked and plotted in a dynamic spectrum which shows how the pattern of scintillation varies with both observing frequency and time.

In modelling the scintillation, we often assume that the signal is scattered by a “thin screen” of density variations (imagine an irregular grid through which light might be diffracted), moving at a certain velocity relative to the radio source. The scattered waves then interfere as they travel further from the screen and the resulting interference pattern is what we receive as scintillation. Multiple thin screens along the line sight can be used to model scattering due to a thicker medium.

Now imagine pairs of waves being scattered by the thin screen: Each pair of scattered waves has a Doppler shift due to the movement of the screen and a time delay between them due to the different path length that each wave has likely followed. A “map” of these Doppler shifts and time delays between every pair of scattered waves can be formed by taking the so-called “secondary spectrum” - effectively the 2-dimensional power spectrum (squared amplitude of the 2-dimensional FFT) of the dynamic spectrum. When this analysis is applied to pulsar observations to study scintillation in the interstellar medium, a clear arc structure termed a “scintillation arc” (first discovered by Dan Stinebring in 2001), is often seen. Over the years this has proved an invaluable tool for probing the interstellar medium.

Now, for we believe the first time, scintillation arcs have been found in the secondary spectra of ionospheric scintillation seen in observations of Cygnus A taken using the KAIRA. It is believed that these also represent the first such broadband (relative to the observing frequency) observations of arcs due to any scattering medium and also the first found using LOFAR hardware. These results have now been written up in a paper recently submitted.

The image shows an example segment of dynamic spectrum and an example secondary spectrum, with the x-axis being Doppler shift and the y-axis being a parameter equivalent to time delay.

Weather radar

Yesterday we described our walk up the ski slopes of Luosto on that hot summer's evening. But what was at the top?

Well, it turns out there is a large weather radar (= säätutka) there. This is operated by our colleagues at the Finnish Meteorological Institute (FMI).

The "blue stone". (Photo: D. McKay-Bukowski)

The FMI weather radar site. (Photo: D. McKay-Bukowski)

Lassi ignores the warning signs. (Photo: D. McKay-Bukowski)

It's a really lovely place. A bit like a lighthouse. A pity it is remotely operated, as I'd so love to work in a place like that.

A bit of a walk

Along similar lines to the recent post on swimming, we have another little adventure. This was the decision on Monday evening to go for a walk... this time to Luosto. Lassi organised this, similar to our excursion last year to Viiankijärvi, which was a chance to get outdoors away from the work and see some Lappish scenery.

Anyway, there are some ski slopes there not far from the Amethyst Mine, and we climbed up the hill there. Today, we have a couple of photographs from that trip... in stark comparison to the conditions of last January. Remember our scene from last time?

Intrepid adventurers from SGO. (Photo: D. McKay-Bukowski)

The ski-slopes... looking forlorn in the summer. (Photo: D. McKay-Bukowski)

Still a great walk, with lovely weather conditions. (Photo: D. McKay-Bukowski)

After the discovery of the giant river pike after our bit of a swim, we might have been quite nervous about what we might have found at the top of the mountain. And indeed there was something quite unusual at the top.

But you will have to wait until tomorrow to find out what it was!

A bit of a swim... the other side of the story

You could barely make this up.

In a bizarre twist to Sunday's "a bit of a swim" story, there was another river story going on just downstream.

At what would have been more-or-less the same time, SGO director Esa Turunen was fishing in the Kitinen river and caught a very large hauki (a type of aggressive river fish common in the waters up here).

Hauki and Esa (Photo: E. Turunen)

But what is "hauki" in English? Well, I guess we could go and ask the fish...

So, fish... what is your English name?

Don't tell him, pike! 

Sorry, couldn't resist that one.

A bit of a swim

Sodankylä Geophysical Observatory is situated along the banks of the Kitinen River. A quick search on the Internet (or looking at all Kitinen-tagged posts on the weblog here), will turn up plenty of photographs of a frozen expanse of ice sheets and sub-zero temperatures. However it does melt in the spring and in the summer it is really quite and idyllic spot.

 

On the evening of the 15th, I decided to see if I could swim across the river. In fact, I first swam across the river, then up to the island and then back again.

The total distance was just over 600 metres, although in reality, I doubt I swam it as absolutely straight lines. There is a current running north to south, so that would have swept me off course a bit. At this time of year, the water is pretty murky, due to the the meltwater seeping through the tundra to get to the river. And the opposite banks are really quite muddy and swampy... so SGO is definitely on the best side of the river here.

Of course the next morning my shoulders were killing me. Even clicking the computer mouse button was a struggle at first. Still, it was all good fun!

Operaatio kakku -- part 2

Yesterday we described the great cake exercise, which was an attempt to have an excuse to engage in conversation with our colleagues from FMI.

Well, the cakes were all completed successfully. They were:

1. Date cake with caramel sauce
2. Sea buckthorn roullade
3. Raisin, lavender and honey roullade
4. Lemon drizzle cake

Cakes #2 (back left), #3 (front) and #4 (back right)

Cleaning up didn't take too long and the cakes were carefully transported to Polaria on the morning of 15 July 2014 (an historical occasion!). The timing was pretty good. FMI had a visiting campaign team there, so we had ample cake for everyone and to spare! So, we've had cake for the next couple of breaks as well.

The remnants of Cakes #1 and #4.

Was it a success? Most definitely. We've now established some sort of rapport to the point where (occasionally) eye-contact is made and even a murmured "hei" (*gasp*). Of course, the first comments from our own staff on returning to SGO were "Ooo... cake... great!... what's the occasion?" and, after the explanation, this was promptly followed by "What! Who authorised that?". Probably in jest, but who knows... in any case, I regard the operation as successful and will continue to extend the welcome to all our colleagues from FMI (not just to come and talk to us at morning coffee at Polaria, but also afternoon coffee at Polaria, and afternoon tea and high-tea at the EISCAT building).

What I want to know, though, is what FMI thought of all this!

Operaatio kakku -- part 1

Last week we (the students and summer workers) were pretty much alone at Polaria at morning and afternoon coffee. In fact, nearly all the SGO staff happened to be on leave. It was deathly quiet. So... alone.

Well, sort of.

In Polaria (the main institute building) the coffee area is shared by SGO (Sodankylä Geophysical Observatory) and FMI (the Finnish Meteorological Institute). The two institutes have coffee at the same time every morning, but sit at separate tables. It is as if there is  barbed wire and land mines between the two.

So, in the absence of any parental control, we (the revolutionaries) formed a cunning plan. Called "Operaatio Kakku" (= Operation Cake), we schemed to make a batch of cakes and the use them as an excuse to go and fraternise with our colleagues from the other side.

Cool!

All we needed now was the cake.

So, after careful and comprehensive planning, we split into two Cake Divisions and set about to accomplish this formidable task. 1st Division was deployed a the guest house to carry out the production of Cake #1, while 2nd Division was set up at the EISCAT building to make a second (and possible third).

Today we have some photographs from the preparation phase!

The planning phase.

Cake #1 was to be a date cake. Made from a trusted recipe (a student has done this before!), the 1st Cake Division over at Guesthouse #3 had this well in hand...

By the time we arrived, the cake was in the oven and the mess cleared up.

1st Division relaxing. They look like they know what they're doing.

Meanwhile at the EISCAT building, Cake #2 was to be a lemon tray bake. This didn't go quite as planned. Firstly, due to a translation error, yours truly had bought the wrong sort of baking paper (voipaperia. not leivinpaperia).

Cake inspection officer... "you've got voipaperia? what?!"

Then we needed to convert normal flour to self-raising flour. Oh... and there were no scales to weight anything. Or measure anything. We just guessed. The recipe was for inspirational -- not instructional -- purposes.

Tray-bake looking a little flat.

 The mixture was sloppy and the tray too big and shallow. At this point we decided to declare a "Cake of Emergency" and started a second batch.

With ingenuity, some Skype-help, an interruption from a colleague (trying to get a scientific paper re-submitted) and a lot of trial and error, we resulted in a new cake and two roulades.

Science meets cooking.

To be continued...

Helicopter at Polaria

Being in the Arctic, we do occasionally get the odd vehicle parked outside the main building. Sometimes tractors, often off-road 4x4 vehicles, occasionally snow-mobiles.

But yesterday the carpark had a different vehicular visitor!

Look what's parked out the front of Polaria! (Photo: D. McKay-Bukowski)

I'd be nervous flying so close to those trees! (Photo: D. McKay-Bukowski)

Cool, eh? (Photo: D. McKay-Bukowski)

The helicopter is here for an FMI experiment. The payload is a series of chemical sensors which are being used to monitor gas species in the atmosphere.

Site clear of snow

The KAIRA site is now clear of snow. I took this photograph very early on Saturday morning and, as can be seen, there is no trace of snow on the KAIRA site itself.

Snow-free KAIRA 2014 (Photo: D. McKay-Bukowski)

Of course, there is still snow (well, ice really) on the mountains and that will remain for a while yet. However, the gullies and banks and under the HBA are now clear.

Third LOFAR Data Processing School

The Third LOFAR Data Processing School will take place at ASTRON in Dwingeloo (The Netherlands), in the week of 17-21 November 2014.

The aim of this School is to introduce the LOFAR system to users and new members of the collaboration who will analyse Cycle data. Students, postdocs, and staff are all encouraged to attend. The school will cover the many aspects of the LOFAR system from the capabilities of the basic station hardware to the software pipelines and science products they produce. Members of the LOFAR project will present lectures and tutorials. Hands-on sessions will also be provided to give attendees an opportunity to gain experience with real LOFAR data.

Presentations will be given at a level appropriate for someone new to LOFAR. Familiarity with the concepts of radio interferometry and standard data processing software such as CASA, AIPS, or Myriad will be useful, but not required. Minimum requirements should include some familiarity with scripting languages and in particular Python. Participants are expected to bring fairly recent Linux or Mac OS laptops with tens of GB of disk space.

The school will be hosted by ASTRON (Dwingeloo). Note that registration to the School is on a first come - first serve basis and limited to 40 participants. In case you are interested in attending the school, we encourage you to proceed with the online registration as soon as possible: http://www.astron.nl/lofarschool2014/registration.php

http://www.astron.nl/lofarschool2014/
lofarschool@astron.nl

Reindeer on the roads

Driving back from KAIRA last night, there were a LOT of reindeer about. Not huge herds (like this example), but scattered patches of them at near-regular intervals. It made for a rather slow trip, with the need to come to a complete stop on multiple occasions. And, as can be seen, it is that time of the year and there are a  lot of young about. Cute... but with zero road sense.

Little reindeer on the road!

RF-container and the mountains beyond

Recently, Thomas Ulich (SGO Head of Measurements) visited the KAIRA site as part of the maintenance/servicing trip and as a general inspection of the site. During that time, Thomas took a number of good photographs and we'll be featuring those over the next few weeks in amongst our other material.

Today we have the first of these, with a shot looking over the RF-container towards the mountains on the Fenno-Norwegian border. The RF-container contains the signal processing electronics that combines the signals from the KAIRA antennas as well as most of the computing.

KAIRA HBA and RF-container (Photo: Th. Ulich)

Congrats to Dr Melessew for his PhD dissertation

Yesterday evening I received excellent news from Bahir Dar University - our colleague Melessew Nigussie has defended his PhD thesis at the Physics Department of the Bahir Dar University. Melessew has been working on TEC models for East-African sector. I have not yet seen Melessew's thesis, but here's a link to one of his publications at Radio Science http://onlinelibrary.wiley.com/doi/10.1029/2012RS004981/abstract. We have a number of joint SGO-BDU projects, hence it is really nice to hear this kind of news! Congratulations!

Melessew Nigussie and Antti Kero in EISCAT Control
Room  (Tromsø, Norway) during the Finnish
EISCAT campaign in November 2013.

Summer workers working

This summer we've had a number of trainees working on a variety of different projects. In an act of brilliance, supervisor Lassi Roininen (left) decided to organise them to all work on one project. In this particular case, it is the spatial interpolation of geomagnetic data.

As you might imagine, this little office has been a buzz of activity all afternoon. We are looking forward to the results!

The 32m dish at Sodankylä

Nothing to report today, so instead we've just got a photograph of the EISCAT 32m VHF dish at Sodankylä. I took this photograph last night just before midnight. Still bathed in sunlight, of course.

The 32m EISCAT dish at Sodankylä Geophysical Observatory (Photo: D. McKay-Bukowski)

LBA height re-survey results

Recently we showed a photograph of the re-surveying of the heights of the Low-Band Antenna (LBA) array at KAIRA. Today, we have the results from that survey.

The plot shows the heights of each antenna in the array with respect to the average height. For the purposes of a phased array, the relative positions are important. Our concern had been that freezing/thawing of the ground would result in shifts in the surface. Additionally, there might be some subsidence on the side where the mound had been built up to match the main field height. In these cases, it is possible that the soil is not sufficiently well packed and that it sinks slightly as it settles further.

As can be seen from the data, the heights are all within the +/- 3 cm specification.

Korkea-Jehkas

Today we have a photograph of the KAIRA site seen from about half-way up Pikku Malla.The lake in the foreground is Siilasjärvi. Behind that is KAIRA and the custom station. Then, the mountain in the background is Korkea-Jehkas. This peak actually has the highest elevation angle, as seen from KAIRA. Although less distinctive, it exceeds the angle raised by Pikku-Malla and Saana.

KAIRA with Korkea-Jehkas in the background (Photo: D. McKay-Bukowski)

PS: The mountain is "Korkea-Jehkas", not "Korkeajännitys"... although perhaps that too!  :-)

Deep-dish pizza

Na ja... it's Sunday and there's not much to report on the weblog. Well, not unless you include pizza! This is a common feature at the observatory, and the one in today's photograph was made from scratch as follows:


Base:

• plain white flour (the rest of the packet, probably 1/2 kg)
• dried yeast (one sachet's worth)
• water (until it was doughy enough)
• pinch of salt (probably been in the cupboard since 2009)
• a few drops of olive oil (from the Nov'2013 campaigns)

Topping:

• tomato paste out of a tiny little tin
• mushrooms, also from a tin
• the left over scrap of a bell pepper
• a few dices of peaches (the rest was for dessert)
• sliced reindeer (like what you'd put on sandwiches)
• dried parsley (it was fresh, but someone didn't water it)
• dried oregano (bought already dried... out of a sachet)
• some random spice whose name I couldn't translate
• cheese, just standard Finnish cheese.

It was pretty deep, as I had a lot of dough, so I gave it some more olive oil, which it soaked up and made it pretty tasty. The whole thing was allowed to rise first and then the topping was added and baked in a glass over dish for 40 minutes or so on some pretty hot setting.

Self-made observatory pizza!

In any case, it turned out well and was very tasty!

Piglet-tail hooks

During the blizzard in March, some of the screws that held the HBA anchors were bent out of shape, resulting in the anchor coming loose. In other cases, the S-haakje would deform to release the anchor.

We have been experimenting with alternative anchor designs to try and come up with a more secure way to hold the anchors in place. Although we cannot change the staafje, we can replace the way the O-ring connects to the timber frameset.

One method is to use a spiralled hook which we refer to as a 'piglet-tail hook'. This lets the O-ring be connected without it requiring the drill. On the other hand, the extra loop still prevents the O-ring from coming loose in the event of extreme wind buffetting.

'piglet-tail' hooks on tile H76. (Photo: D. McKay-Bukowski)

Re-surveying the LBA

As part of the summer maintenance, we surveyed the LBA heights. One of the concerns was that the freeze/thaw cycle in the soil and gravel that supports the LBA would cause subsidence or a minor 'palsen' effect which in turn would distort the array field.

To carry out this test, we used a laser level and investigated the relative heights of the different aerials. This task was carried out by some of our summer workers.

Conducting the LBA survey with the laser level is in the foreground. (Photo: D. McKay-Bukowski)

HBA billowing

In high winds, the covers of the HBA tiles can billow up. This places stress on the edges of the covers and, in extreme conditions, can lead to tile failure. During the recent repair work we had several occasions where this billowing effect was visible.

HBA tiles billowing up along the NW edge (Photo: D. McKay-Bukowski)

Securing the LBA

We attempted to effect repairs on the KAIRA LBA, but we were short of some parts (cable connectors), which meant that some aerials needed to remain down.  In order to ensure that the existing parts were secure, we used tape and rocks to prop up the posts and permit water drainage. It looks a little odd, but it works!

The few remaining damaged LBA aerials (Photo: D. McKay-Bukowski)

At present, we have 1 tile and 4 aerials out of action. We hope to repair the LBAs in July/August and we are waiting on a quote from ASTRON for a replacement tile.

Fixing HBA damage

In March we lost one HBA tile and had several others damaged by the blizzard. Last week we repaired one of the more badly damaged tiles, replacing shattered polystyrene parts and re-securing the cover.

Assessing H65 (Photo: D. McKay-Bukowski)

Internal damage on HBA H65 (Photo: D. McKay-Bukowski)