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Cryospheric Sciences

Iceland

Image of the Week – Icelandic glaciers monitored from space!

Image of the Week – Icelandic glaciers monitored from space!

Located in the North Atlantic Ocean, just south of the polar circle, Iceland is a highly fascinating land. Covered by some of the largest glaciers in Europe and hosting active volcanoes, geothermal sites and subglacial lakes, it is extremely dynamic in nature and ever changing. With this Image of the Week we will tell you a bit about the changing ice caps of Iceland and how we can monitor them from space!


Icelandic ice caps since the mid-1990s

Iceland enjoys a mild and moist climate because of the relatively warm and saline Irminger current transporting heat to its southern coast, although the cold East Greenland and East Icelandic currents may cause sea ice to form to the north. Iceland’s ice caps, which receive abundant precipitation from North Atlantic cyclones, cover about 11% of the land, and contain ~3600 km2 of ice. If they completely melted they would contribute 1 cm to Sea Level Rise (SLR).

In the period 1995-2010, Icelandic glaciers shrank every year and lost mass at an average rate of 9.5±1.5 Gton a-1 – generally reflecting higher summer temperatures and longer melting seasons than in the early 1990s (Björnsson et al., 2013). Importantly, in recent decades Iceland has been the second largest source of glacier meltwater to the North Atlantic after Greenland and its peripheral glaciers. Furthermore, surge-type outlet glaciers – which have unpredictable dynamics – are present in all Icelandic ice caps and represent as much as 75% of the area of Vatnajökull (Bjornsson et al., 2003), the largest ice cap in Europe by volume. Therefore, it is important to continuously monitor Icelandic ice caps (>90% of the whole glaciated area) at high spatial resolution. Glaciological field surveys can yield accurate measurements and are routinely performed in Iceland on all ice caps and most glaciers. However, it is not always feasible to use field methods, depending on the remoteness and size of the glacier (e.g. several glaciers and ice caps in the Arctic). Continuous monitoring of such hardly accessible areas can be achieved from space at high spatial resolution.

Continuous health check from space

Since 2010, the ESA CryoSat-2 (CS2) mission has been fundamental in retrieving ice elevation data over glacial terrain characterised by complex topography and steep slopes – notoriously hard to monitor via satellite. CS2’s radar altimeter provides the elevation of the Point-Of-Closest-Approach (POCA) – the point at the surface closest to the satellite on a straight line – every ~400 m along the flight track. The main novelty of this mission is the use of a second antenna, which allows the use of interferometry across-track to accurately infer the location of a surface reflection in presence of a slope (read more about it here). Additionally, a new and exciting application of CS2 interferometric capabilities is that we can exploit the echos after the POCA, i.e. the reflections coming from the sloping surface moments after the first one. This approach generates a swath of elevations every ~400 m and provides up to two orders of magnitude more elevation data than with conventional POCA processing (Fig. 2; Gray et al., 2013, Foresta et al., 2016).

Since 2010, the ESA CryoSat-2 (CS2) mission has been fundamental in retrieving ice elevation data

Figure 2: Example of the improved elevation data using CS2 swath-processing. CS2 swath data (colors) and conventional (circles) heights over the Austfonna ice cap (Svalbard) for two satellite passes. Swath processing delivers up to two orders of magnitude more elevation data. [Credit: Dr. N. Gourmelen,University of Edinburgh, School of GeoSciences]

This rich dataset can be used to generate maps of surface elevation change rates at sub-kilometer resolution (Figs. 1 and 3). These maps show extensive thinning of up to -10 m a-1 in marginal areas of Iceland’s ice caps, while patterns of change are more variable in their interior. Fig. 3 shows the difference in spatial coverage between the POCA and Swath approaches, with the former sampling preferentially along topographic highs (see for example the Langjökull ice cap in Fig. 3). Using these high resolution maps, it is possible to independently infer the mass balance of each ice cap purely from satellite altimetry data. Based on CS2 swath-processed elevations, between glaciological years 2010/11 and 2014/15 Iceland has lost mass at an average rate of 5.8±0.7 Gton a-1 contributing 0.016±0.002 mm a-1 to SLR (Foresta et al., 2016). The rate of mass loss is ~40% less than during the preceding 15 years, partly caused by Vatnajökull (63% of the total mass loss) having had positive mass balance during the glaciological year 2014/15 due to anomalously high precipitation. Langjökull, with widespread thinning up to the ice divide (Figs. 1 and 3), is the fastest changing ice cap in terms of mass loss per unit area.

between glaciological years 2010/11 and 2014/15 Iceland has lost mass at an average rate of 5.8±0.7 Gton a-1 contributing 0.016±0.002 mm a-1 to SLR

Beside estimating mass change at the ice cap scale, the novel swath approach demonstrates the capability to observe glaciological processes at a sub-catchment scale. Different accumulation and thinning patterns over Vatnajökull and Langjökull, for example, are directly related to past surges or subglacial volcanic eruptions, some of which happened decades ago. Their long term lingering effects on the ice cap topography are now visible from space and as the satellite data record extends we will be able to gain an increased understanding of how these effects evolve over time.

Figure 3 – Comparison between swath-processed (Swath) and conventional (POCA) surface elevation change rates over the six largest ice caps in Iceland, representing 90% of the glaciated area. V (Vatnajökull), L (Langjökull),H(Hofsjökull),M(Mýrdalsjökull), D (Drangajökull), and E (Eyjafjallajökull). The inset shows the location of individual elevation measurements by using Swath and POCA approaches over Langjökull. [Credit: After Foresta et al. (2016).]

Edited by Emma Smith


Luca Foresta is a PhD student in the Glaciology and Cryosphere Research Group at the University of Edinburgh (@EdinGlaciology), and his research focuses on improving CryoSat-2 processing as well as exploiting swath-processed CryoSat-2 data to quantify surface, volume and mass changes over ice caps.

 

Ice on fire at the Royal Society Summer Science Exhibition

Ice on fire at the Royal Society Summer Science Exhibition

The Royal Society Summer Science Exhibition (RSSSE) is a free public event 4-10th July 2016 in London. This is a yearly event that is made up of 22 exhibits, selected in a competitive process, featuring cutting edge science and research undertaken right now across the UK. The scientists will be on their stands ready to share discoveries, show you amazing technologies and with hands-on interactive activities for everyone! The Royal Society has historic origins – going back to the 1660s and today it is the UK’s national science academy working to promote, and support excellence in science and to encourage the development and use of science for the benefit of humanity. If you can get yourself down to London this week then it is definitely worth a look!

The Royal Society Summer Science Festival Exhibit Hall. Photo Credit: Thorbjörg Águstsdóttir

The Royal Society Summer Science Festival Exhibit Hall. Photo Credit: Jenny Woods


What is there to see?

This year there are a number of ice-related exhibits. The “4D science” exhibit uses X-ray computer tomography to look inside ice cream and the “Explosive Earth” exhibit showcases ice-volcano interactions in Iceland using earthquakes. The Summer Science Exhibition yearly attracts around 12,000 visitors. This is a unique opportunity to meet cutting edge scientists, discover their research and try out fun and engaging activities for yourself.

Left: The Explosive Earth presented by the Cambridge University Volcano Seismology Group. Left: 4D Science: Diamond Light Source, University of Manchester and University of Liverpool - Looking inside materials through time

Left: The Explosive Earth presented by the Cambridge University Volcano Seismology Group. Right: 4D Science: Diamond Light Source, University of Manchester and University of Liverpool – Looking inside materials through time. Photo Credit: Jenny Woods

Explosive Earth!

The Explosive Earth exhibit has been put together by the Cambridge Volcano Seismology group. They explore many applications of volcano seismology, from what we can learn about movement of molten rock (magma at more than 1000°C) in the Earth’s crust and rift zone dynamics, to the very structure of the earth itself. They currently focus their research in central Iceland where they operate an extensive seismic network in and around some very active volcanoes, many of which are under Europe’s largest ice cap Vatnajökull. The seismic network detects tiny earthquakes caused by the movement of magma beneath the surface, which often occurs under volcanoes prior to eruption. By studying these seismic events, they hope to be able to predict volcanic activity better in the future. Their exhibit at RSSSE showcases current research in this explosive field of volcano seismology.

 

Eyjafjallajökull – 2010: an explosive eruption that disrupted air traffic

The 2010 eruption at Eyjafjallajökull (image at the top of the page) occurred beneath a glacier, which caused a highly explosive eruption. When hot magma comes into contact with ice the magma cools and contracts and the ice turns to steam and rapidly expands. This shatters the solidifying magma and produces ash. The explosivity of the interaction, and the pressure of all the rising magma underground, blows the mixture of ash, volcanic gases and steam high into the air, creating an eruptive plume. The 2010 Eyjafjallajökull eruption produced an ash plume that reached up to 10 km (35,000 feet). The fine ash was then carried 1000’s of km by the wind towards Europe where it grounded over 100,000 flights.

Installing seismometers in a variety of locations around Iceland to monitor tiny earthquakes from magma movement under the surface

Installing seismometers in a variety of locations around Iceland to monitor tiny earthquakes from magma movement under the surface. Photo Credits – Left: Rob Green, Right: Ágúst Þór Gunnlaugsson

 

Bárðarbunga-Holuhraun – 2014: a gentle eruption that affected air quality

In 2014 a completely different kind of eruption happened in central Iceland, also originating from a volcano under the ice. Magma flowed underground from Bárðarbunga volcano, beneath Vatnajökull ice cap, fracturing a pathway so far from the volcano that when it erupted there was no ice at the surface. Without the magma-ice interaction, the eruption was comparatively gentle and the molten rock simply fountained out of the ground, reaching heights of over 150 m. No ash was produced, only steam and sulphur-dioxide. The amount of magma erupted was much greater than in 2010 (an order of magnitude higher), but there was no impact on air travel because there was no ash plume. The Explosive Earth team are investigating the 30,000 earthquakes that led up to this spectacular six-month eruption in Iceland, to try and find out more about what happened and why. The earthquakes tracked the progress of the molten rock as it moved underground, away from Bárðarbunga volcano to the eventual eruption site at Holuhraun, 46 km away.

The fountains of lava accompanied by clouds of steam and sulphur-dioxide. The magma flowed 46 km underground from Bárðarbunga volcano to the eventual eruption site at Holuhraun, where it erupted continuously for 6 months. Photo Credit: Tobias Löfstrand

The fountains of lava accompanied by clouds of steam and sulphur-dioxide. The magma flowed 46 km underground from Bárðarbunga volcano to the eventual eruption site at Holuhraun, where it erupted continuously for 6 months. Photo Credit: Tobias Löfstrand

Cambridge Volcano seismology group in front of the fissure eruption on the first day of the 2014-15 Bárðarbunga-Holuhraun eruption.

Cambridge Volcano seismology group in front of the fissure eruption on the first day of the 2014-15 Bárðarbunga-Holuhraun eruption. Photo Credit: Thorbjörg Águstsdóttir

What can monitoring these earthquakes tell us?

Monitoring volcanic regions in Iceland is important because eruptions are frequent and have wide-range impacts:

  • Explosive eruptions under ice can cause rapid and destructive flooding of inhabited areas downstream, and can propel huge ash clouds into the atmosphere, disrupting air travel around the globe.

  • Gentle eruptions, producing large lava flows, can release millions of tones of harmful gases, affecting the local population and in some cases the global climate.

Studying earthquakes helps to understand the physical processes that occur in volcanic systems, such as how molten rock intrudes through the Earth’s crust and how the centre of a volcano collapses. The more we understand about the behaviour of these systems, the better we can forecast eruptions.

“Explosive Earth” exhibits earthquakes and eruptions in Iceland in a fun interactive way. You can find out more details of the science behind why and how these eruptions happen and how it is possible to monitor volcanic activity in Iceland using earthquakes. As a taster of what you can see, try entering your postcode into their lava flow game to see how big the Holuhraun lava flow is and how far it travelled underground prior to erupting. Other interactive activities include making your own earthquake and testing your reaction times with an earthquake location game.

BANNER_exhibit

(Edited by Emma Smith and Sophie Berger)


tobba_headshot.jpgThorbjörg Águstsdóttir (Tobba) is a PhD student at the University of Cambridge studying volcano seismology. Her research focuses on the seismicity accompanying the 2014 Bárðarbunga-Holuhraun intrusion and the co- and post-eruptive activity. She tweets as @fencingtobba, for more information about her work see her website.

Image of the Week — Glowing Ice

Image of the Week — Glowing Ice

Two weeks ago, the EGU General Assembly was coming to an end in Vienna. With over 16,500 participants, this year’s edition was bigger and more varied than ever (e.g check out this good overview of the science-policy short course, published 2 days ago on geolog). The week was particularly fruitful for the cryospheric sciences and to mark this we have cherry-picked one of the winning picture of the EGU photo contest 2016 as our image of this week. It’s great that an image of the cryosphere is a winner in this competition and we are pleased to see that it isn’t only us that go bananas for pictures of ice!

What do we see?

The beautiful shot shows a stranded block of ice on the shore the glacial lagoon Jökulsárlón, south-east Iceland. Ice calves off Breiðamerkurjökull, an outlet glacier which flows out from Vatnajökull, the ice cap which makes up the largest ice body of Iceland. Jökulsárlón developed as Breiðamerkurjökull retreated away from the Atlantic ocean (into which it flows) and the lagoon continues to grow in size as the glacier continues to retreat (see image below).

Panorama of the Jökulsárlón glacial lake, Iceland, 2010. [Credit: Ira Goldstein (via wikimedia commons)]

Panorama of the Jökulsárlón glacial lake, Iceland, 2010. [Credit: Ira Goldstein (distibuted via wikimedia commons)]


The image comes from imaggeo, what is it?

You like this image of the week? Good news, you are free to re-use it in your presentation and publication because it comes from Imaggeo, the EGU open access image repository.

(Edited by Emma Smith)

Image Of The Week – Do My Ice Deceive Me?

Image Of The Week – Do My Ice Deceive Me?

A few weeks ago, we focussed our image of the week on very particular parts of Antarctica, which display blue ice at the surface.

Today we would like to put the spotlight on an even more extreme chromatic phenomenon : the Fyndið ísjaki Brandari (should be pronounced “/fɪːntɪð/ˈiːsjacɪ /ˈprantaːrɪ/“, even though a bit of phonetics never hurt anyone, for the sake of simplicity this phenomenon will be referred to as the FIB).

Despite our poor understanding of the FIB, this phenomenon has been recognised since ancient times. According to Icelandic folklore, FIB has been observed in remote regions at the centre of ice sheets and ice caps for many hundreds of years and was originally thought to indicate a unicorn breeding ground. However, recent studies have begun to find a more scientific explanation for this truly wonderful phenomenon.

Dr Joe Kerr, the world specialist of FIB, told us that the presented picture was an exceptional shot because colour changes, known as Layered Ice Extraordinaire (LIE), are aligned with isochronic layers, indicating a time-dependant source for the changes in colour. He even concluded that this specific FIB shows indications of originating from ice which has travelled to Iceland from tropical regions, although more thorough dating (using a new mobile software package known as TINDER) of the layering must take place to confirm this.

On the other hand, Prof Han-Ki Ding, a competitor for the title of FIB world specialist, also inspected the picture and does not agree with his colleague Joe Kerr. Han-Ki Ding, hypothesises that the thick layer of white snow on top of the coloured layers is indicative of ice of a polar origin. He even added that the snow layer that is sagging on the left part of the image provides further evidence. Recordings of a high pitched noise, know as an “ice scream“, were made when the snow collapsed into its current position. Careful analysis showed that in this particular case the collapse emitted a “coo kiedough” ice scream – indicative of ice originating at high latitudes.

Of course we could further discuss the connection between the FIB and unicorn breeding grounds but then our story would not be plausible anymore, and you might realise that today is April Fools Day… Anyway we thank you – the readers – for wasting a few minutes of your time reading this entirely uninformative post and we hope it made you smile in the process 🙂

Edited by  Emma Smith and Nanna Karlsson