Sounds of the planet

Acoustic remote sensing and its uses in underwater environments

Topic: From the field

Finding Nessie … or close enough …

  , , ,

📥  From the field

The Loch Ness monster is one of the most famous mythical beasts, supposedly lurking below the cold waters of Loch Ness in Scotland. But there has been no conclusive proof of its existence yet, despite many people searching for it over the years … Until …

Looking for animals, even very large, in a long and deep fjord like Loch Ness is like looking for the proverbial needle in a haystack. During a visit to the Loch Ness Monster Museum, long ago, I had seen old sonar records purportedly from “something” lurking in the deep, although my sceptical eye interpreted this as long-range noise in the records … Later, more accurate sonar maps of the bottom of the Loch Ness had revealed structures, more or less circular, build of rocks and rubble and placed at regular intervals. Some journalists of course used the occasion to talk of “monster nests”, but the truth was much more prosaic, if as interesting. As I wrote in my 2009 Handbook of Sidescan Sonar, these structures were associated with the building of the road along the shore. Debris from the construction were loaded onto barges, which dumped everything unceremoniously in the deeper parts of the loch. And, like any collection of objects falling in deep water, these rocks arranged themselves in rough circles.

But this time, even the BBC reported it. So it looked much more serious, and I started reading … This Nessie was a lost prop from a movie several decades ago, not a real, live animal. It was found by my colleagues at Kongsberg Maritime, using a combination of the latest technologies now available: high-resolution sonars, capable of mapping both the topography of the loch’s bottom and its acoustic reflectivity, and the Autonomous Underwater Vehicle MUNIN, their latest model. Their website has a very nice (and short) movie of how they found it. It really is a needle in a haystack!

 

30 July 2014 - Return to the Glacier

📥  From the field

Today, we have done most of our work and we even took a short break. For two hours, we went for a walk at the foot of the 500-metre high mountain overlooking the base.  The main purpose was still scientific, looking at Hans Glacier from above and checking the latest signs of calving. There are two autonomous recorders on the bottom at the end of the fjord now: one is still recording noises from the glacier and the icebergs (and the hydrographic vessel, still anchored not far).

On the way, we see flocks of little auks returning from the sea. They are extremely noisy, and it seems there are thousands of birds all shouting at once (there probably are). The ornithologists tell me they nest in the rocks (no twigs here, of course, to build up nests). The auks try to find comfortable holes in the ground, frozen most of the year, and sometimes use burrows 1.5 m long deep. This removes most of the surrounding cold and also the threat of predators.

Talking of predators, we were cautiously avoiding groups of reindeers, napping on the soft, green moss, when a dark speck suddenly reared its head on our path. It was an Arctic fox, who looked at us with increasing interest, then bolted out to go to the closest snow patch.

As it sees us arriving, this Arctic fox scampers away and observes us from afar.

As it sees us arriving, this Arctic fox scampers away and observes us from afar.

We saw fresh reindeer bones that he was gnawing on: no doubt scavenged from further away. The fox comes back as soon as we are at a safe distance, and carries on eating ...

After more walking and climbing on small rocks and different small moraines, we arrive just above the glacier. Still a lot of blue ice at its front, meaning the bottom ice is still being exposed and calves into the sea. There are many blue icebergs drifting away ... Up close, we can see the base of the glacier, and its sides, are eroded and form flanges. A small rivulet of icy water trickles on one side and into the sea ... It's beautiful, and also extremely informative: the base layer of glaciers is usually made of a slush of ice and water, lubricating it so that it can move forward. The surface of the glacier is criss-crossed by crevasses and similar features. Some of the Polar Station's crew regularly take measurements of the glacier's movements, using GPS and markers placed at key points on the ice. A risky business, but they seem very experienced (and very safety-conscious too: I talked with one of them yesterday, and most of his backpack was filled with safety-related equipment).

A different view from our favourite glacier.

A different view from our favourite glacier.

 

28 July 2014 - The bright side of life

  , , , , ,

📥  From the field

Polish TV recently showed the farewell concert of Monty Python and "The bright side of life" (my Polish is still extremely limited, but I could understand that much ...) (especially the English part ...) For the last 24 hours, the sun has been shining and I can see its bright rays illuminating the glaciers and moraines on the other side of the bay of Isbjornhamna. Today, we are going to do experiments in the deepest parts of the fjord, and sail there for a large part of the day. We launch our boat shortly after another party of scientists has left for the fjord of  Hans Glacier.  Amongst them is a friend and former Bath postdoc, Aleksandra Kruss. A multibeam sonar expert with an international reputation, she is out there to test the latest generation of high-resolution sonar in this challenging environment. She also kindly agreed to take measurements of the front of the glacier, to help us in our interpretations. She has extensive Arctic field experience so we know she won't get too close to the glacier for safety, but the sonar should do an excellent job at mapping what it looks like underwater.

The bright side of life: this side of Isbjornhamna is graced with a few rays of sunshine ...

The bright side of life: this side of Isbjornhamna is graced with a few rays of sunshine ...

In the meantime, we move to a slightly different type of landscape: very eroded mountains, and much less green. No moss, no lichen visible from the boat: no animals either. The Polar Station has disappeared at the horizon: even finding the peak below which it stands, we cannot see it. The ride to the other side of the bay took us 40 minutes, bumping into the waves on our small Bombard C5. After 20 minutes of measurements, we realise the site is not suitable, and move to a different location, on the original side of the bay (another 40 minutes, bumping into the waves, making sure we fall back into the boat and clinging tightly to the ropes ...). There, we can make the right kind of measurements. We also understand why no one had ever made this before: it's hard, it's cold, and we have to do several trials and use our field knowledge of underwater acoustics before getting it right ...   After many hours drifting in the cold wind and short waves, we have all the results we want and head home. Cold to the bones (it takes me until this evening to warm up, despite the many layers of clothes), but delighted with the results. Which we start analysing immediately after cleaning the equipment, untangling several hundred metres of cables and of course manhandling the boats back on shore (Aleksandra and her colleague are back too: but their boat is fortunately lighter, or maybe it's the fact we are now 5 people hauling it ...)

 

27 July 2014 - Ships passing in the night ...

  , , , , , , ,

📥  From the field

The small icebergs brought to the shore have fallen silent with the evening. The sun is currently hidden behind the 500-metre mountain just behind the base, and the beach is in shadows. What suddenly made these icebergs silent? Curious, of course, we came to investigate after some colleagues told us there was no noise ... (motivated by some aspects of our research, they had combed the beach looking for icebergs with the most bubbles to add to their end-of-work drinks ...) We take measurements in air and in water, and conclude it is a conjunction of the type of icebergs, the contrasts in temperature (or rather the absence: air and water are both close to 1 degree Celsius), and the very calm seas ... We also take some samples to measure in the laboratory ...

Traffic in the Bay of White Bears has increased tonight: there is a large cruise ship at anchor in the deepest part (around 200 m deep), and we can hear the noise of its engines over the several kilometres of water. Another ship (further left in the picture), much smaller, decided to moor very close to where we had deployed an acoustic-recording buoy ... What about the noise it will make, covering what we want to measure over the coming months?

They are Norwegian hydrographers, though, so we do not really begrudge them: they must be doing exciting work too. And we all "comrades-in-arms": we all want to understand more about the polar regions and their climate. Thinking a bit more about it, our first buoy has been there for several months already. The second buoy, 25 metres away, will not start recording until November. So a few hours of engine noise will not really affect our different measurements ...

Ships passing in the night? If only ... One of them has been above our buoy for more than 24 hours now ...

Ships passing in the night? If only ... One of them has been above our buoy for more than 24 hours now ...

 

26 July 2014 – No birds, please …

  , , , , ,

📥  From the field

After the last days, we have plenty of field data to analyse and more experiments to run and test different theories. Is the noise coming from the bubbles? From the cracking? What influences how loud it is? Is it the temperature of the air? Of the water? Of the ice itself? Does it depend on how much salt there is in the water? And how does the noise from one iceberg combine with the noise of the others to give what we measure in the field?

This acoustic experiment fits nicely on a table top, and measures the noise of individual growlers as they melt ...

This acoustic experiment fits nicely on a table top, and measures the noise of individual growlers as they melt ... The box on the left contains hydrophones for use in the field, listening to icebergs (or anything underwater) in stereo.

This makes a lot of parameters to investigate. The high-speed photography rig is used fully, day and late into the night, and we have another small tank to run tests in.  The second part of our laboratory is actually in our dormitory: I annexed the desk and put a small aquarium on top. The hydrophone measuring the sound close to melting ice is connected to different bits of kit, and everything is recorded on my computer for later analyses. Melting full growlers in different conditions requires as little background noise as possible. This is not always possible in the local conditions: the station was built to be a polar base, not an underwater acoustics lab, and it is mounted on stilts (to separate from the snow and cold permafrost, in winter). This means that people walking in the corridor outside make the floor move. Doors closing too fast because of the wind do not help. But the main culprits are outside: squabbling geese or cheerful snow buntings settling just below the window.

Snow buntings are the only songbird in Svalbard.  The same size as sparrows, they are a delight to see and hear. But what do they need to sing loudest when the experiments are running :-) ?

Snow buntings are the only songbird in Svalbard. The same size as sparrows, they are a delight to see and hear. But why do they need to sing loudest when the experiments are running?

 

 

25 July 2014 – Fifty shades of blue

  , , , , ,

📥  From the field

We do not do as much field work as I expected at the beginning, because of the weather and because we need to do laboratory experiments to check different theories. But today I am happy: the weather is cooperating, and we are away in the field once again.

The glacier has changed over the last days, with more and more blue ice and blue icebergs. Ice from the top of the glacier is white, and becomes blue when it is compressed at the base of the glacier. The front of Hansbreen is gleaming in different shades of blue today, meaning more ice from the base has been exposed and is now melting. There are large blue icebergs all around us.

A typical blue iceberg, calved from the bottom of the glacier. It is around 3 m high above the water: there is 80% more below the water line ...

A typical blue iceberg, calved from the bottom of the glacier. It is around 3 metres above the water line: there is 80% more below ...

The icebergs in the fjord have various shades and various shapes. Some of them are so flat that I would like to step on them (too dangerous to even think about, of course, as their bobbing in the waves reminds us how unstable they are). A Canadian friend sent me the link to a video showing a large iceberg capsizing: very illustrative, even though I prefer watching it with the sound off. Other icebergs look like melting bouncy castles, complete with high towers and oscillations. Some are smudged with grey or brown: remnants from the base of the glacier, gravel or mud taken with the ice as it moves slowly but ineluctably. Sometimes, the icebergs still have huge stones caught into the ice. This one (below) looks a gruyere cheese: the holes were once occupied by round stones, which fell into the water as the ice melted. Closer to the Station, on our way back, some of the icebergs with the most melting behind them look like swans: all white with slender necks …

Gruyere iceberg: the holes had large stones in them, from the bottom of the glacier. This was the base of the iceberg, which has now capsized.

Gruyere iceberg: the holes had large stones in them, from the bottom of the glacier. This was the base of the iceberg, which has now capsized.

During our first deployment of DAB, a little auk swam enquiringly toward us, curious of what we were doing. After seeing it was “just science”, it swam further away, and started ducking its head into the water at regular intervals to find some food.

Once back on shore, late into the night, I have time to glance outside whilst downloading the data from the day. Some sort of eagle is swooping over one of the barnacle goose chicks by the melt pond, and even the parents (usually aggressively protective of their young) do not seem ready to approach. But the chick runs to water … and apparently to safety, as the eagle now flies higher and finally leaves off …

 

 

24 July 2014 – Glacier ice cubes and glacier work

  , , , , ,

📥  From the field

Yesterday saw another successful deployment of DAB, the Directional Acoustic Buoy to track where underwater noise comes from exactly. Each survey starts in the same way: zooming in the boat to the fjord with the glacier, jumping on the beach to set up the cameras on the hills, and jumping back in the boat to deploy the DAB and get measurements. Zooming is of course an exaggeration: getting away from the base is a cautious start, as the skipper needs to negotiate between rocky outcrops (not visible at high tides, but still there and dangerous) and sometimes icebergs, Crossing the open sea to the fjord cannot be done too fast if the waves are too high, or the wind in the wrong direction. And once into the fjord, we have to zigzag between icebergs of different sizes. Jumping out of the boat is also an exaggeration: the seabed is very steep, and we have to wait until the very last seconds for the water to be shallow enough, getting into the water and holding on to the boat before painstakingly pushing it on shore away from the waves and the tide. Then, we lumber up the hill in our immersion suits. But the view from the top is worth it …

From the hill where our cameras are deployed, we get wide views over the entire Hans Glacier and its fjord, covered with icebergs of different sizes.

From the hill where our cameras are deployed, we get wide views over the entire Hans Glacier and its fjord, covered with icebergs of different sizes.

Today, we successfully deployed the long-term buoy which will measure ambient noise as winter sets in. We programmed it to start taking measurements from 15 November until the batteries run out (which should be in March 2015). This way, the buoy will record the onset of the ice cover in the fjord, and hopefully when it starts to break up in spring. To celebrate these different achievements, Jarek breaks out the whisky he had brought with him from Longyearbyen. And I carve some ice cubes out from one of the iceberg samples we brought back to the base for our experiments …

In the confined space of our dormitory, we have managed to organise a small celebration of a series of successful deployments. The ice cubes in the “wee drams” are carved from fresh ice samples.

In the confined space of our dormitory (Grant squeezed into one of the bunks to take this picture), we have managed to organise a small celebration for a series of successful deployments. The ice cubes in the “wee drams” are carved from fresh ice samples.

 

 

23 July 2014 - Hump day

  , , , ,

📥  From the field

A few days ago, it was already “hump day”. This is a custom taken from long surveys on ships, where people use the analogy of the camel hump to mark the days “up”, toward the middle of the survey, or the hump, and the days “down”, where each day takes us closer to the end, but also to the return to normal life, to family and loved ones, to the favourite pub down the road or to the comforts of home and the choice of our own food or our own entertainments.

In the past, I have been on rather long surveys, for two months or more, and “hump day” is often marked by a more or less official (and more or less unbridled) celebration. Here, this is more of a muted affair. First, because our team of three is the only one for which this is “hump day”: the others are here for longer, or shorter, or started at different times. Second, because we luckily get on well together, and the Polish Polar Station is much more homely than a deep-sea vessel. I love going on ships, and the excitement of scientific discovery as we survey new grounds is hard to surpass. But one must admit that, after a while, we are still all bundled together for several weeks in very confined spaces, with hard work and very limited entertainment. And it’s impossible to “step outside” to be alone, or oneself, for a change.

Front entrance to the Polish Polar Station. The arrows point to features of interest: Biegun (North Pole = 1,452 km) = , Arctowski (South Pole) = 16,252 km, Longyearbyen (the nearest settlement) = 136 km. The mast is decorated with a knitted Polish flag: guerilla knitting taken to extreme latitudes.

Front entrance to the Polish Polar Station. The arrows point to features of interest: Biegun (North Pole = 1,452 km) = , Arctowski (South Pole) = 16,252 km, Longyearbyen (the nearest settlement) = 136 km. The mast is decorated with a knitted Polish flag: guerilla knitting taken to extreme latitudes.

The Polish station has access to the outside world: I can Skype with my family on a regular basis, receive and send emails and we also have access to satellite TV. Granted, the network speed is very slow: I sometimes see letters appearing on the screen 5-15 seconds after typing them, and Skype conversations often have to be audio-only because of the limited bandwidth. The satellite connection is sometimes down when the weather turns bad, or when the connection at the other end fails to recognise internet addresses (“bath.ac.uk: host cannot be resolved”). But this is still better than no connection, and being cut off from the rest of the world for months on end. We can follow the heat wave in Europe (and feel very happy for our own “heat wave”, with temperatures as high as 5 degrees), and other international affairs.

And, contrary to ships, the fact we do not work on shifts means we have more freedom to get a break every now and then. The Station has a well-stocked bookshelf. Most of it is in Polish, obviously, but there are other books given by visitors over the years, in other languages. A book by Julian Dowdeswell (a famous polar explorer and scientist, now based in Bristol) is on the same shelf as “The Guide to Mammals and Birds from Svalbard”, from the Norwegian Polar Institute, not to be confused with “The Guide to Flora and Fauna from Svalbard”, translated from Polish and giving the best directions for collecting and storing specimens, from plankton to parasites to larger sample. The TV is often switched on in the communal area, allowing us to see Harry Potter (in Polish), Iranian children’s programmes (one of the scientists here is learning Farsi in his spare time), or any satellite channel we please. Obviously, with the pace of work I haven’t had much time to watch it much (a few minutes at most). But, like the Opera in Sydney, knowing it’s there if you want to access it always makes us feel better.

Another factor that makes life better, even if working hard and being away from home for long, is the food. Here, we are lucky to have two chefs (Piotr and Daria), helped by a few scientists on roster duty each day. The food is varied, appetising, and includes both traditional Polish fare (from beetroot juice to beetroot soup to varied types of sausages) and different offerings (Chinese food two days ago, pancakes this morning, and even homemade pâté two weeks ago). The meals are set on the communal table, sitting 20 people at a time (there are often two sittings, when everybody is here) and leftovers are available in the fridge, for evening dinners (at no fixed time, although we all tend to meet around the coffee machine around 8-9 pm) and anytime cravings.

 

 

22 July 2014 – Pulled under by a mini-tsunami

  , , , , , , , ,

📥  From the field

7 am: The weather has cleared up and we can start field work again. According to Internet, we are in the sunshine. According to my own eyes, the clouds are still very low and all grey from one end of the horizon to the next. This morning, the beach was littered with small and big icebergs. Their clinking noise could be heard even from the base, 200 m away. After piling all the equipment in the boat,  we are going back to Hans glacier, first to set up the stereo cameras on the hill overlooking it, second to get more underwater measurements. After the rain of the last days, the glacier has melted a bit more, and there is a lot of ice, including blue ice, everywhere around (blue ice is more compressed ice, coming from the base of the glacier).

9 am: Just as we approach the beach, a loud bang can be heard, and we turn back in time to see parts of the glacier falling off. We have seen that before, and it is always spectacular. As blocks of ice fall into the water, they create long waves, which do not seem that bad from our place. We use the first ones to help haul the boat onto the beach. And then the big one comes in … It looms large very quickly, bringing a 5-tonne iceberg too close for comfort … And then the gravel below my feet is pulled down, and I feel sucked into the water deeper than I expected … Luckily, the Arctic immersion suit is once again very useful …

I should have known: mini-tsunamis are a common risk near glaciers, and like other tsunamis, their height increases as they reach shallower water. Here in this fjord, the seabed is very steep, so the waves increase only very close to the shore. In other places in the Arctic, they can crash big icebergs onto structures or small harbours (when the places are settled).

Not very fetching, but it does the job: the Arctic immersion suit is ideal for very cold water.

Not very fetching, but it does the job: the Arctic immersion suit is ideal for very cold water.

10 am: The stereo cameras were easy to set up, with practice, and we will gather pictures every 5 seconds for the several hours to come. During this time, we’ll be drifting with the freshwater outflow from the glacier, measuring the noise underwater and finding ourselves in the middle of a very large and noisy ice flow.

Ice, ice everywhere ... and we are in the thick of it, drifting for several hours in cold wind ...

Ice, ice everywhere ... and we are in the thick of it, drifting for several hours in cold wind ...

Icebergs, icebergs everywhere … We have to push the pointiest ones away from the rubber tubes of our boat. Icebergs make clunking noises as they move below the aluminium hull, or big thumps when colliding with us (more or less gently).

11am : we get close to a very nice iceberg, made of blue ice and roughly 15 m large. Sea gulls use it as a vantage point, and it has already started to melt in a variety of interesting shapes. The seabirds turn around us with interest, before flying back to their resting place. We take the paddles out to move away (without too much noise: this would be bad for the measurements), and a few minutes later, this iceberg capsizes several times … Lucky escape …

A big blue iceberg: it will capsize violently (and noisily) ten minutes later. The watching seagull at the top will be unfazed, and use the occasion to dive for more fish.

A big blue iceberg: it will capsize violently (and noisily) ten minutes later. The watching seagull at the top will be unfazed, and use the occasion to dive for more fish.

1 pm: The rest of the measurements get by without excitement, as we get colder and colder despite our warm clothing. The walk up the hill to recover the cameras is a good way to warm up (I am on polar-bear watch and carry the rifle and emergency radio, fortunately not too heavy).

3 pm: Back to the shore. Someone is waiting for us to point at a relatively less dense group of icebergs. With Grant, we jump down in the water for the last few metres, moving the icebergs by hand away from the boat so that we can beach it safely. We are back in time for a good lunch, and can relax later to the sound of Mozart on an old vynil from the station’s collection, in the communal room. Then it will be back to work, downloading the data, checking the dozens of emails that accumulated at work back in our respective institutions, and preparing for tomorrow’s deployment. The network is slow again (kilobytes/second) and most connections do not work well … Typing letters. I see them on the screen 5-10 seconds later …

Midnight:: The autonomous recorder is now ready for tomorrow, and we cleaned our hands from the lubricant used to waterproof all the joints and connections. Time for more work: the rain outside looks suspiciously like sleet but I am not going to investigate. It’s warm and cosy inside.

 

 

20 July 2014 – The wild side of Arctic life

  ,

📥  From the field

Conditions in the Arctic vary rapidly, and local ecosystems are very simple (no rodents or hares, for example, in this part of Svalbard) (no worms, no slugs, but a few insects). There are many other animals around, though, and they are mostly unaware that humans can cause a threat. In the case of polar bears, this is justified … (and before anyone asks, no, I have not seen a bear yet: just a pawprint on the beach once, and that’s as far as I am keen to go …)

The bay we are on is called Isbjjørnhamna, after the ice-breaker “Isbjørn” used in early 20th century expeditions. It also means the bay of the polar bears, and Jarek tells me that this is often used in winter by bears migrating from eastern to western Svalbard. The area was used by Norwegian hunters until the 1950s (when the station was built). Polar bear hunting is banned since 1973 in Svalbard, and only self-defence is allowed. Some bears are said to cross the ice-covered seas in winter to move all the way to Greenland … Impressive!

The Polish Polar Station has two big Arctic dogs, used to extreme weather and sometimes seen lazily soaking up the mist on the cold tundra, in the same way that dogs back home would soak up the sun on the lawn. They are used to warn of bears, although I was told one was eaten by a polar bear a few years ago … There are also plenty of geese, roaming around with a few fluffy chicks and being very protective. The first night, I heard a commotion outside before going to bed, and saw an Arctic fox running away with something small in its mouth, being pursued for a few metres by some angry geese. With seabirds, this is apparently their primary food source during the summer, and the local guidebook assures me they have plenty of food in this season.

Other animals roaming happily around us are reindeers: three of them can be seen happily munching on anything that grows, from lichen to moss to a few clumps of grass or even flowers. They are not disturbed by humans walking around, and they come and go at leisure around the bay.

One of the reindeers roaming around the station. Left and in the mist: Wilczekodden Peninsula, with its cross and open-air altar, erected in 1982.

One of the reindeers roaming around the station. Left and in the mist: Wilczekodden Peninsula, with its cross and open-air altar, erected in 1982 by the station's personnel

Seabirds come in all sorts, from black guillemots to eiders (I saw one flying across our boat this morning, or at least I think it was one), and little auks, nice small black-and-white birds with a short beak. Several of the scientists working at the station study them: the birds have one chick per brood, and one brood per year. Both parents take equal care of raising their young, often with the father staying in the nest after hatching whilst the mother moves around.  The scientists study prolactin, the hormone regulating bonding behaviour, and stress hormones. They could tell me everything about these birds’ migration patterns too: they travel to the deep sea far away, where they gorge on plankton …

Arctic geese in the mist – The weather turned to cold rain in the space of a few hours …

Arctic geese in the mist – The weather turned to cold rain in the space of a few hours …