Archives for the month of: September, 2013

Sunday 22nd September.

It is good to not expect everything to go according to plan.  Last Sunday (22nd September), the plan had been to head up North and fly to Svalbard (~78 °N), land and refuel at Longyearbyen, and then sample and do more science in the Svalbard area, before heading back to Kiruna. But it was not meant to be exactly that way. The wind speed had picked up at Longyearbyen, above the threshold which would make it unsafe for the BAe-146 to take off from there. So the plans were changed in the morning, hours before the flight was supposed to take off, but then even these plans turned out not feasible either, and finally with some resolute decisions by the mission scientists John Pyle and Keith Bower, and with 1¾ hours delay, we left Kiruna. Instead of the two flights we were only going to have a single flight, and still achieve the key objective: sampling air near Svalbard that been transported there from Russia, i.e. sampling long-range transport of methane.

Svalbard in the distance, as the ARA flies off its west coast. (Photo credit: Jennifer Muller)

Svalbard in the distance, as the ARA flies off its west coast. (Photo credit: Jennifer Muller)

As we still needed to go as far north as Svalbard to measure these air masses advected into this part of the Arctic, and get back to Kiruna in one flight, we headed out North at high altitude (because flying low uses more fuel). Before reaching Bear Island, we descended down to lower level at 73 °N, and then surveyed different altitudes by “saw-toothing”. This basically is making the shape of the tooth on a saw, meaning going up and down vertically in the atmosphere; for us this was between 1000 feet and minimum safe altitude, whilst travelling horizontally northwards to Svalbard. Saw-tooths are useful when trying to find the altitude of a particular aerosol and pollutant layer in the atmosphere. The models had forecasted that we would find such a layer south of Svalbard, but the enhancements in methane concentrations we measured were on the smallish side.  Coming up west of Svalbard, we stayed low over the ocean, which was a little choppy, before turning around at 78 °N and heading back at high altitude to Kiruna.

We went up north to measure methane that had been transported there from further east, and we did indeed sample some of that (so, success!) but there was also a whole lot of cloud around on Sunday. And in the way the saying goes “If life gives you lemons, make lemonade”, I would say Sunday was a case of “If life gives you clouds, measure clouds”. Graeme Nott from FAAM ran the core cloud instruments on the flight (i.e. cloud physics measurements, such as e.g. cloud droplet or ice number, size and type) and at some point he had an interesting conversation with Mission 1 Keith Bower over the intercom, all about bullet rosette ice crystals, and out of focus imaged ice crystals which look like donuts on the display.  Always something new to learn!  We also flew through some very wispy, thin ice cloud which was not obvious by looking out of the window, and only Graeme could tell us whether we were in-cloud or out-of-cloud.

Broken up cloud streets - interesting, even to a chemist! (Photo credit: Jennifer Muller)

Broken up cloud streets – interesting, even to a chemist! (Photo credit: Jennifer Muller)

Although my research interests are atmospheric trace gases, such as methane, I couldn’t help to thoroughly enjoy this flight for the myriad of clouds we saw. Yes, sometimes you get what you think you don’t want, and you just have to go with the flow, enjoy and make the best of it. This is also what Stéphane Bauguitte from FAAM did, who creatively used the flight delay in the morning to make and distribute some tongue in cheek “Complimentary drinks vouchers”.  Yet with what we saw and measured, as well as the delicious Swedish cakes, courtesy of the flight deck, there was enough to keep us scientists sweet and happy during this flight.

–Dr Jennifer Muller, University of Manchester

Complimentary drinks voucher, to keep everyone sweet while their flight was delayed by nearly two hours.

Complimentary drinks voucher, to keep everyone sweet while their flight was delayed by nearly two hours.

We’re been a little light (and slow) on the written reports from this field campaign, partly because we’ve been so busy making podcasts! Well, Jennifer and Sam have anyway. So, while you wait for the next instalment of the blog, head over to the Barometer Podcast site, where you’ll find short audio interviews with aircraft engineers, operations staff, scientists, and more…

http://thebarometer.podbean.com/

Sam is recording a podcast with Dave in the car on a very rainy Sunday, on our way to collect samples in the birch woodland. (Photo "credit": Michelle Cain.)

Sam is recording a podcast with Dave in the car on a very rainy Sunday, on our way to collect samples in the birch woodland. (Photo “credit”: Michelle Cain.)

Here, Prof. Euan Nisbet provides us with an explainer on methane hyrdates, which could potentially release methane into the atmosphere as the ocean warms, and how we are going to target our measurements to find out more about them. 

The MAMM team board the ARA after refuelling at Longyearbyen, Spitsbergen, during the MAMM field campaign in 2012.

The MAMM team board the ARA after refuelling at Longyearbyen, Spitsbergen, during the  field campaign in 2012. The ARA will soon be sniffing out the methane in the Arctic air. Photo credit: Michelle Cain.

Our flights across the Barents Sea (like the one being attempted today) are designed to assess the methane releases into the Arctic atmosphere. Using knowledge about the wind, the atmospheric research aircraft can ‘sniff’ methane sources thousands of miles upwind from its flight path (note: methane has no smell to humans, but our laser-based instrument is a very sensitive methane-sniffer). The “cavity ring-down spectroscopic” system operated by FAAM (Facility for Airborne Atmospheric Measurements) and the University of Manchester is so sensitive that it can sniff at a precision better than one molecule in every one billion molecules in air – as sensitive than the keenest hound.

There have been many news stories recently about the problem of methane release from the huge amount stored a few hundred metres under the surface in the Arctic, within the enormous deposits of a water-methane structure called methane hydrate. In the past few years, several papers in scientific journals have suggested that huge amounts of methane are already being released from hydrate, and in July this year an article in the prestigious journal Nature modelled the enormous impact this might have (Whiteman et al., Vast costs of Arctic change, Nature, 25th July 2013, 401-3).

To look for methane in the high Arctic, the aircraft flies high and low across the Arctic Ocean. The high flights can measure the methane in the middle of the troposphere (the main part of the atmosphere), while the low flights, close to the sea surface, measure the methane in the “boundary layer” (or near-surface), where surface sources mix up into the winds. By back-tracking the winds, we can sniff methane sources many thousands of miles away and determine where they have come from. For example, if there is an easterly wind, a flight north of Norway can measure methane released by sources far away in northern Russia. This is a sort of methane telescope — or, to use the Greek for nose, a “methane telerhino” — is used just in the way a fox sniffs a chicken coop upwind. Using even more sophisticated methods such as carbon isotopic analysis of the carbon atoms in methane by the Royal Holloway University team, we can tell what “type” of methane it is – for example, whether it is methane that has been emitted from microbes in wetlands or natural fossil gas. Using measurements of other gases from instruments such as a mass spectrometer, we can also say from where those gases originated with greater confidence as we know that certain processes should emit specific gases together (e.g. formic acid and methane in forest fires).

What is hydrate, and why might it be important?

Gas Hydrates (also known as clathrates) are ice-like materials made by gases such as methane and CO2, and water. Think of freezing Coca-Cola. They are stable under pressure and cold temperatures. There can be an enormous amount of gas stored in them, and when they are heated up they release this gas. They exist all round the world where methane gas seeps up into wet sediment in the right pressure and temperature conditions. They occur in the Amazon delta, in the Gulf of Mexico deep oilfields, and very widely in the tropics, stabilised under the pressure of a fairly thick sediment load. In the Arctic the cold temperatures help stabilise hydrate at much shallower depths. Offshore, the sea water a few hundred metres down is close to 0oC and methane hydrates are stable near the seabed under about 300 to 400m of water. Near-shore, in shallow salty water that can be as cold as -2oC, hydrate is stable under a few hundred metres of sediment or less. Onshore, in extremely cold areas where the mean annual temperature can be as low as -10oC, hydrates can be stable quite close to surface.

As hydrates warm, they can potentially release great quantities of methane. This is a powerful greenhouse gas – the warming can then feed the warming. Long ago, in the 1980s, Gordon MacDonald  and Euan Nisbet independently worried that there might be a link between warming hydrates and climate.  An old but more-or-less still valid figure from Nisbet’s 1989 paper (below) shows where the hydrates occur and how they respond to warming.

This figure is ancient, but still more-or-less relevant. The curves show the stability of the hydrates 0.5 to 100 years after a surface warming to +5C. From Nisbet, E. G. (1989).

This figure is ancient, but still more-or-less relevant. The curves show the stability of the hydrates 0.5 to 100 years after a surface warming to +5C. From Nisbet, E. G. (1989).

Nisbet, E. G. (1989), Some northern sources of atmospheric methane – production, history and future implications, Can. J. Earth Sci.26(8), 1603-1611.

MacDonald, G. J. (1990) Role of clathrates in past and future climate change. Climate Change

16, 247-82. See also text of MacDonald’s 1983 comment in http://www.killerinourmidst.com/MH and global climate.html.

Bubbles seen by ships – is the Arctic shelf degassing?

For some years, there has been an extremely interesting annual voyage across the east Siberian Arctic Shelf led by Nathalia Shakhova and Igor Semiletov of the Univ. of Alaska at Fairbanks. This is remarkable scientific work in a very important and little studied region. In 2010, Shakhova et al. reported major methane emissions from the eastern Siberian shelf and suggested the annual outgassing might be as much as 8 million tons, enough to be globally significant (the world emits somewhat over 500 million tons annually from all sources, human and natural). However, in the scientific discussion following the publication, the quantification of the emission was disputed. Much of this shelf is flooded peatland, which can also release methane when the permafrost melts.

Shakhova, et al. (2010) Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf. Science 327, 1246

Methane emissions from seabed hydrates were also found off Spitsbergen by a major NERC study from the ship RRS James Clark Ross. About 250 plumes of gas bubbles were seen.   The plumes were discovered by ‘fish-finder’ sonar (more commonly used to search for cod than methane!). Bubble trains came from the edge of the gas hydrate stability zone, and some reached nearly to the surface. Rebecca Fisher and Mathias Lanoisellé from the Royal Holloway group were on the ship (they’ve now taken wings on the FAAM aircraft). The plumes were reported by  Westbrook et al (2009):

Westbrook et al.  (2009) Escape of methane gas from the seabed along the West Spitsbergen continental margin. Geophys. Res. Lett. 36, L15608.

The emissions were in response to seawater warmth, but this was off W. Spitsbergen where the water is at the northerly end of the Gulf Stream, where the warmth is brought north from the Gulf of Mexico.

Is Godzilla about to arise? Is there a methane monster?

In the 25th July issue of Nature this year, Whiteman et al. suggested a monster methane release is about to occur in the Arctic. They modelled a release of 50 Giga-tons of methane from Arctic hydrate, at 5 Gt a year over 10 years from 2015 to 2025. One Giga-ton is 1000 million tons, or 1015 grams.  To put this in context, the total amount of methane in the world’s air now is about 5 Gt, and the annual input is about 0.5 Gt, so this would double the methane in the air within the first year.  They based this number on a  ‘single stage blowout’ scenario from another paper by Shakhova et al, (2010). The Whiteman et al. paper had immediate press interest, from newspapers as prestigious the Guardian and the New York Times to a wide range of  blogs.

Contrary voices were also heard, in particular from researchers on methane and hydrates (including the present author). They were widely sceptical of such large releases. Responses were both published later in Nature, and also a posted comment that is accessible by scrolling far down the page on:

http://www.nature.com/nature/journal/v499/n7459/full/499401a.html

The full text is on:

http://equianos.com/wordpress/wp-content/uploads/Response-to-Whiteman_et-al-Comment.pdf

There’s clearly a great deal of methane hydrate in the Arctic, and much of it is likely to be destabilised by Arctic warming. But is it going to come out as a great sudden burst in a few years? Or is it going to dribble out as a chronic release, as suggested in 2008 by David Archer, a recognised hydrate expert?  Remember also that the northern wetland methane emissions respond very fast to warming. There’s much evidence that at the end of the last glaciation it was not primarily the hydrates but the wetland response that drove the very rapid increase in methane.

Archer, et al (2008) Ocean methane hydrates as a slow tipping point in the global carbon cycle, Proc. Natl. Acad. Sci.  106, 20596–20601

Nisbet, E.G. and Chappellaz, J., (2009) Shifting gear, quickly. Science 324, 477-8

The scepticism of Arctic researchers about the 50 Gt blowout scenario was initially dismissed by an influential Guardian blog as “narrow arguments of scientists out of touch with cutting edge developments in the Arctic.” http://www.theguardian.com/environment/earth-insight/2013/aug/05/7-facts-need-to-know-arctic-methane-time-bomb

However, later the comment was modified:

http://planet3.org/2013/09/05/nafeez-ahmed-responds/#comment-40721

The answers to these puzzles is what we’re trying to find out….

MAMM Flights to the High Arctic

Our MAMM flights are designed to measure the Arctic winds. If the 8 million ton per year methane emission inferred by Shakhova et al (2010) is already happening, this outpouring will produce an excess of methane in the polar air above the regional temperate background. If the winds are suitable, we should be able to detect that as we fly north in the polar air.

The ARA flying over Spitsbergen for MAMM in 2012.

The ARA flying over Spitsbergen for MAMM in 2012.

Of course it all depends on what the winds bring us, but we can go searching. This is what Michelle Cain and colleagues at the UK Met Office do – they use a weather model to predict where the air will come from. In the same way that the modellers predict how clouds of volcanic ash will travel to disrupt airline flights, so they can work out where the air is coming from. That means we can move the aircraft flight path, and go up and down in altitude, to seek out air masses that have come from the Siberian shelf, or from the vast Russian and Siberian wetlands.

And that is exactly what the flight today on the ARA is aiming to do. Follow this blog to find out how it went.

–Prof. Euan Nisbet, Royal Holloway University of London

Friday 20th September, afternoon.

After the thick cloud of the morning flight, and a satellite picture that showed cloud cover over the whole area we wanted to fly in, things were not looking too promising for this afternoon’s flight. This is because we want to fly low over the wetlands (at minimum safe altitude, which is about 500ft), however the pilots need to have sight of the ground in order to descend that low. With this in mind, we were slightly worried that we might not be able to get down to low level at all!  But the only way to know what is out there is to go out and see, so we set off with our fingers crossed.

We were planning to head north out of Kiruna, but somewhere along the line some wires got crossed, and the pilots set a course to the way point to the south. The confusion unfolded thusly (I paraphrase):

Ian (pilot): heading for way point N7.

Keith (mission scientist one): do you mean N1?

Ian: no, way point N7.

Keith: Oh.

So we decided there was no real reason why going to N7 or N1 was any better than the other, so we proceeded. And in the end, we concluded that this was a sound decision and Ian should be more involved in the flight planning in future! This is because after flying for a short while within the cloud layer, we found a break and descended to our favoured low altitude. And the first leg at this level (shown below) was excellent for measuring a methane and carbon dioxide gradient! In the figure below, the methane (black) and carbon dioxide (red) shown is for the west-to-east leg shown in the flight track plot. The first half of the leg shows a gradual decrease in methane, which then levels out. This is consistent with many other flights we’ve done. This could be because there are a lot more pine trees and sandy soil in the eastern end, which are not really methane emitting.

The first part of our flight track, alongside preliminary methane (black) and carbon dioxide (red) measurements.

The first part of our flight track, alongside preliminary methane (black) and carbon dioxide (red) measurements.

So despite the initial confusion, and the potential for a complete wash-out, we got some great measurements which will add to those we already have. And we got home in time for dinner (back to the hotel before 7pm for once) so all in all, a most successful day’s flying!

–Dr Michelle Cain, University of Cambridge

Friday 20th September, morning.

After yesterday’s transit to Kiruna and late afternoon wetland flight, today saw the first full day of MAMM ‘Science’ flying for the September 2013 campaign. The two teams of mission scientists once more split up into the ‘red’ and ‘azure’ teams, with the azure team drawing the short straw and getting the morning flight. This was a particularly exciting flight for me, as it was my first in the ‘hot seat’ as Mission Scientist 1. Unfortunately, the first thing that became apparent was that my legs were about 3” too long to afford me anything resembling comfort, although for any instrument scientists that may be reading this is proof positive that us mission scientists do occasionally suffer for our art as well.

The basic premise of today’s flight was to do some low level flying over northern Swedish and Finnish wetlands, and (as with the August 2013 flights) hoping to observe a methane gradient in the East-West legs with Southerly prevailing winds. Unfortunately a low cloud layer meant that we had to fly at around 5000 feet, but there was still a reasonably strong methane gradient that will be interesting to look at during the analysis. After this we flew North to the South Arctic Ocean, where we sampled what looked like methane emissions being blown from the northern Scandinavian wetlands. There were also some interesting methane enhancements at about 7000 feet that we observed when we were profiling, and we were able to make some bag measurements of these for isotopic analysis.

All in all it was a very successful flight, in which all of the intended targets were met, and I can safely report that view from the front of the cockpit was absolutely stunning, and almost entirely made up for the fact that I spent the rest of the day feeling like the male lead from ‘Misery’.

–Dr Sam Illingworth, University of Manchester

Thursday 19th September 2013, afternoon.

I am sure everyone who read my first post will be desperate know how my day turned out…! Well, somehow, my train arrived in Kiruna on time, despite setting off 1h45 late. And in a lucky twist, the ARA had taken off late and so landed late at 3pm local time. So James and Nicola picked me up from the station, and I got to the hangar at the same time as the aircraft. In another twist of fate, Seb who was on the afternoon’s crew list was not actually going to fly. So there was a space for me to fly! That shower and change of clothes would just have to wait…

Being the first science flight, we we all super-keen and there was an overabundance of mission scientists, meaning that as a lowly additional extra, I didn’t have anywhere to plug in my laptop from the seat that I was in. Alas, my laptop ran out of battery half way through, so I wasn’t able to monitor the measurements in real-time for the second half of the flight. As we were flying at low level for most of the flight, the seatbelt sign was on so I couldn’t even get up to charge my laptop elsewhere. Instead, I took lots of photos of the land that we were flying over, as (a) I was lucky enough to have a window seat and (b) the amount of methane coming out of the ground will depend on the vegetation cover, so it’s a useful record of that. (NB I haven’t got the time data from the flight as I write this, so I can’t link the photo times with their locations right now. If I have time, I’ll do that once I get hold of that information. It’s a bit too hectic in the middle of a campaign to get all the data in the right place – especially as I’m writing this in my hotel room late at night!)

Anyway, here’s the far-from-comprehensive story of the flight in pictures…

Our nominal flight plan, to give you an idea of where we were flying.

Our nominal flight plan, to give you an idea of where we were flying. We started and finished at Kiruna.

5pm (all times are Swedish local time). It's too cloudy to descend to minimum safe altitude. Just waiting for a break in the clouds so we can get down to near the ground.

1700 (all times are Swedish local time). It’s too cloudy to descend to minimum safe altitude. Just waiting for a break in the clouds so we can get down to near the ground.

1709: A mixture of forest and wetland areas.

1709: We managed to find a break in the clouds and fly down near the surface at minimum safe altitude. A mixture of forest and wetland areas.

1723: The seasons are changing near Abisko.

1723: The seasons are changing near Pallas, Finland. The orangey blobs are deciduous leaves changing colour. Beautiful!

1739: north of Pallas there are quite a lot of lakes.

1739: north of Pallas there are quite a lot of lakes.

1812: Much of the land further north was like this. Not sure what this beige coloured stuff is, but I shall ask around to find out!

1812: Much of the land further north was like this. Not sure what this beige coloured stuff is, but I shall ask around to find out!

1812: taken right after the previous photo, this darker wetland area was also widespread.

1812: taken right after the previous photo, this darker wetland area was also widespread. I wonder if more methanogens are present in one land type or another?

1834: After sampling the wetlands, we have ascended to above the cloud layer. Time to head home!

1834: After sampling the wetlands, we have ascended to above the cloud layer. Time to head home!

–Dr Michelle Cain, University of Cambridge

Thursday 19th September 2013, morning.

Here we are again, in the Arctic for the final MAMM field campaign. Well, I’m actually not quite in the Arctic yet, as I’m currently on a train that has just departed from Boden, which is at about 65.5N, just half a degree south of the Arctic Circle.

The plan for this September campaign is to measure methane at this time of year, so see how it differs from the warmer months of July and August. It’s not that cold in the wetlands yet (still in double figures during the day, and nowhere near freezing at night) so we may still see evidence of wetlands emissions.

The ARA is currently in the air, on its transit flight from the UK over to Kiruna. My train was supposed to be getting in to Kiruna around the same time as the aircraft, so I could have been there for the debrief and brief for this afternoon’s flight. Alas, the UK railways are not the only ones that have delays! A broken down train blocking the rails meant that my sleeper train departed 1h45 late. We managed to makeup some time, and the connecting train from Boden to Kiruna waited for the delayed sleeper, but I will still be too late for the briefing unless they too are delayed. I wasn’t going to fly this afternoon, so it’s not too much of a problem; I’ll just have to catch up with what’s going on when I do arrive.

And I must say, I’m quite glad (and my colleagues certainly will be glad) that I can check in to the hotel and have a quick shower before going to the airport, as I’ve been on the road for over 24 hours now…

View from the train, on my way up to Kiruna. A bit rainy, but some of the trees are looking a pretty as the leaves turn yellow and orange.

View from the train, on my way up to Kiruna. A bit rainy, but some of the trees are looking a pretty as the leaves turn yellow and orange as the seasons change.

Dr Michelle Cain, University of Cambridge