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Image of the Week – Hidden Beauty on a Himalayan Glacier

Image of the Week –  Hidden Beauty on a Himalayan Glacier

Today’s image of the week comes from stunning setting of Chhota Shigri Glacier in the Pir Panjal Range of northern India. The range is part of the Hindu-Kush Karakorum Himalaya region which is a notoriously challenging place to work as it is very remote and completely inaccessible during the winter months. However, when have these challenges ever stopped a hardy glaciologist?! 

Our image this week was taken during a field expedition as part of an ongoing long term monitoring program in the area and today we are going to tell you why the region is so important (other than being the source of some rather good photos!)


Why is monitoring glaciers in the Himalaya so important?

Location of Chhota Shigri Glacier taken from Wagon et al., 2007

The Hindu-Kush Karakorum Himalaya region is made up of the biggest mountain ranges on Earth which contain the largest ice mass outside of the polar regions. This region provides water to 50-60% of the world’s population (Wagon et al., 2007), some of which comes from glacial melt water, therefore it is critical to understand how the glaciers in this region may respond to ongoing climate change and predict the impact this may have for the future. As glaciers are very sensitive to changing climate they are also used to understand climate variations at annual and decadal timescales in the region.

Chhota Shigri Glacier is representative of many glaciers in this region and was chosen as the site for a long-term monitoring program in 2002. It was chosen for a number of reasons including previous field studies on the glacier in the 1980s,  glacier geometry, accessibility and its dynamic environment; with areas of partial debris cover and supraglacial lakes (as seen in the image above). The data record on this glacier now continuously spans 13 years and the program has become a benchmark for studying Himalayan glaciers.

What do we see on the picture

The beautiful shot shows a supraglacial lake, a pond of liquid water, on the top of the Chhota Shigri Glacier. This supraglacial lake is an ephemeral lake, forming immediately after winter season. Supraglacial lakes form due to the melting of snow/ice and their presence helps to determine surface melt rates. When the lake water drains it also allows the distribution of subsurface hydrological conduits to be investigated. If the lake does not drain and exists long term there may be glacial lake outburst floods. These are a natural hazard and must be monitored and better understood. This is just one of the aspects of Chhota Shigri Glacier that is being investigated by the long term monitoring program.

Chhota Shigri Glacier has the longest monitoring record

The long term monitoring program, initiated on Chhota Shigri Glacier in 2002, has recorded the evolution of mass balance, ice velocity, ice thickness, stream runoff and melt water quality. The program is a joint collaboration between India and France under the frame work of DST/CEFIPRA programme at School of Environmental Science, Jawaharlal Nehru University, New Delhi. Presently, the annual and seasonal mass balance series (13 years) of Chhota Shigri glacier since 2002 is the longest continuous record in the entire Hindu-Kush Karakorum Himalaya region and represents a benchmark for climate change studies in this region. To measure the annual and seasonal mass balance, we survey the glacier at the end of winter season (May/June) for winter balance measurements and end of summer (September end/October) for annual measurements. We monitor a network of ablation stakes distributed throughout the entire ablation zone (including debris-covered area) to estimate the glacier-wide ablation. To estimate the accumulation we drill snow cores or dig snow pits at representative locations within the accumulation zone (>5150 m) of Chhota Shigri Glacier. For more detailed information and the results of this monitoring see Azam et al. (2016) and Ramanathan (2012).

Long term monitoring on Chhota Shigri Glacier (a) accumulation zone at the end of summer (area is largely covered in dust with clearly visible medial moraine . (b) accumulation zone at the end of winter (fresh snow cover), (c) ablation stake (bamboo) installation in a partly debris covered region during the summer and, (d) drilling of snow core at top of the glacier during winter (Credit: Arindan Mandal/JNU).

Long term monitoring on Chhota Shigri Glacier (a) accumulation zone at the end of summer (area is largely covered in dust with clearly visible medial moraine . (b) accumulation zone at the end of winter (fresh snow cover). (c) ablation stake (bamboo) installation in a partly debris covered region during the summe. (d) drilling of snow core at top of the glacier during winter (Credit: Arindan Mandal).

 

Acknowledgements

Thanks to Department of Science and Technology, Govt. of India, SAC-ISRO, CEFIPRA, INDICE, GLACINDIA and CHARIS for funding our research. Special thanks to Emma and Sophie for help in putting together this post.

Edited by Emma Smith and Sophie Berger


Arindan_PhotoArindan Mandal is a PhD student at the School of Environmental Science, Jawaharlal Nehru university, New Delhi, India under the supervision of Prof. AL. Ramanathan. His current work is focused on Chhota Shigri Glacier where he is working to analyse the past and present state of mass balance in the changing climate scenario and also to understand the complex local scale meteorological processes that drive the mass balance of the glacier. He is working to develop a coupled distributed surface energy-balance model combined with various glaciological and hydrological aspect using in-situ dataset to understand the processes that govern and runoff at Chhota Shigri glacier pro-glacial stream and its sensitivity to the future climate. He tweets as @141Arindan.
Contact Email: arindan.141@gmail.com,

Image of the Week — Looking for ice inside a volcano !

Image of the Week —  Looking for ice inside a volcano !

Who would think that one of the world’s most active volcano shelters the southernmost persistent ice mass in Europe!?

Yes, you can find ice inside Mount Etna!

Located at an altitude of about 2,040 m above sea level, the Ice Cave  (Grotta del Gelo) is well known among Mt Etna’s volcanic caves due to the presence of columns of ice on its walls and floor which occupy about the 30% of the cave’s volume and persist all year round.

How did the ice get there and why does it remain?

  • This cave a small lava tube of less than 100 metres long was formed during Etna’s longest eruption that occurred on its northern flank from 1614 to 1624 A.D. (Marino, 1999)
  • Once formed, the cave was subsequently filled with ice.
  • The shape of the cave enables the ice to persist because there is only one single entrance to the ice cave that insulate the air from the outside. This enables the temperature to stay below 0°C in some parts of the cave all year round. This is not the case with other lava tubes around Etna that have several entrances, which allows the air to circulate within the caves, causing warming

Exploring the Ice Cave

By studying ice inside caves, researchers can obtain very useful biological and paleo-climatological information. Although we don’t know much about the conditions of the ice mass and its evolution over the last few centuries, speleologists (Centre Speleogico Etneo) and scientists (Italian National Institutites of Geophysics and Volcanology) have studied the cave for the past 20 years.

The use of new technologies such as UAV’s (see THIS or THIS previous blog posts about other applications of UAVs in glaciology) or terrestrial laser scanners on glaciers and ice caves can give the possibility to monitor surface variations of hidden underground areas that have never been affected by human activities.

This year, researchers and speleologists from the Inside The Glaciers Project, organised a first expedition to the cave, to acquire precise measurements of the ice mass surface, with a terrestrial laser scanner.

After a long walk of about 4 hours through beautiful volcanic landscapes, the Inside The Glacier team arrived at the entrance of the cave. There they surveyed the Ice Cave for 5 hours, performing 17 scans to detect the ice mass with very high accuracy.

With these measurements it was possible to draw detailed topographic plant and sections of the cave and derive 3D models of its surfaces, obtaining first data that will be compared in future with other laser scanner surveys to help scientists to study the evolution of the ice mass inside the cave.

Topographic plant and profile of the Ice Cave derived from laser scanning data. Ice deposits are represented in cyan color.[Credit: Tommaso Santagata]

Topographic plant and profile of the Ice Cave derived from laser scanning data. Ice deposits are represented in cyan color.[Credit: Tommaso Santagata]

Acknowledgements

This expedition was organized within the “Inside The Glaciers” Project in collaboration with the Association La Venta Esplorazioni Geografiche, Etna Natural Park, Italian National Insitute of Geophysics and Volcanology (I.N.G.V.), Centro Speleologico Etneo, Federazione Speleologica Regionale Siciliana, Gruppo Servizi Topografici s.n.c.

(Edited by Sophie Berger and Emma Smith)


tom_picTommaso Santagata is a survey technician and geology student at the University of Modena and Reggio Emilia. As speleologist and member of the Italian association La Venta Esplorazioni Geografiche, he carries out research projects on glaciers using UAV’s, terrestrial laser scanning and 3D photogrammetry techniques to study the ice caves of Patagonia, the in-cave glacier of the Cenote Abyss (Dolomiti Mountains, Italy), the moulins of Gorner Glacier (Switzerland) and other underground environments as the lava tunnels of Mount Etna.
He tweets as @tommysgeo

Image of the Week – How ocean tides affect ice flow

Image of the Week – How ocean tides affect ice flow

Ice streams discharge approximately 90% of the Antarctic ice onto ice shelves , and ultimately into the sea into the sea (Bamber et al., 2000; Rignot et al., 2011). Whilst flow-speed changes on annual timescales are frequently discussed, we consider here what happens on much shorter timescales!

Previous studies have shown that ice streams can respond to ocean tides at distances up to 100km inland (e.g. Gudmundsson, 2006 ; Murray et al., 2007; Rosier et al, 2014); new high-resolution remotely sensed data provide a synpoptic-scale view of the response of ice flow in Rutford Ice Stream (West Antarctica), to ocean tidal motion.

These are the first results to capture the flow of an entire ice stream and its proximal ice shelf in all three spatial dimensions and in time.

The ocean controls the Antarctic ice sheet

The ice-ocean interface is very important as nearly all ice-mass loss occurs directly into the ocean in Antarctica (Shepherd et al., 2012). Many areas terminate on ice shelves (the floating ice that connects with the land ice), which are fed by the flow of ice from the ice sheet. Any changes to the floating ice shelf alter the forces acting on the grounded ice upstream, therefore directly affecting the ice sheet evolution (e.g. Gudmundsson, 2013; Scambos et al, 2004).

Because ocean tides are well-understood, we can use the response of grounded ice streams to ocean tidal uplift over the ice shelf to better understand how ice sheets respond to ocean-induced changes.

An ice stream and ice shelf respond to forcing by ocean tides

Floating ice shelves are directly affected by tides, as their vertical displacement will be altered. These tidal variations are on short timescales (hourly to daily) compared to the timescales generally associated with ice flow (yearly). The question therefore is, how much can the tides affect horizontal flow speeds, and how far inland of the ice shelf are these effects felt?

The movie below, by Brent Minchew et al, shows the significant response of Rutford Ice Stream and its ice shelf to forcing by the tides. Using high-resolution synthetic aperture radar data they are able to infer the significant spatio-temporal response of Rutford Ice Stream in West Antarctica to ocean tidal forcing. The flow is modulated by the ocean tides to nearly 100km inland of the grounding line. These flow variations propagate inland at a mean rate of approximately 30 km/day and are sensitive to local ice thickness and the mechanical properties of the ice-bed interface. Variations in horizontal ice flow originate over the ice shelf, indicating a change in (restraining force) over tidal timescales, which is largely attributable to the ice shelf lifting off of shallow bathymetry near the margins. Upstream propagation of ice flow variations provides insights into the sensitivity of grounded ice streams to variations in ice shelf buttressing.

Horizontal ice flow on Rutford Ice Stream inferred from 9 months of continuous synthetic aperture radar observations. (a) Total horizontal flow. Colormap indicates horizontal speed and arrows give flow direction. (b) Detrended horizontal flow variability over a 14.77-day period. Colormap indicates the along-flow component (negative values oppose flow) while arrows indicate magnitude and direction of tidal variability. Contour lines give secular horizontal speed in 20 cm/day increments. (c) Modelled vertical tidal displacement over the ice shelf. (Credit : Brent Minchew)

Reference

B. M. Minchew, M. Simons, B. V. Riel, and P. Milillo. Tidally induced variations in vertical and horizontal motion on Rutford Ice Stream, West Antarctica, inferred from remotely sensed observations. submitted to JGR, 2016

(Edited by Sophie Berger and Emma Smith)


facepic

Teresa Kyrke-Smith is a postdoctoral researcher at the British Antarctic Survey, on the iSTAR grant. She works on using inversion methods to learn about the nature of basal control on the flow of Pine Island Glacier in West Antarctica. She completed her PhD two years ago in Oxford; her thesis focused on the feedbacks between ice streams and subglacial hydrology.

Brent Minchew is an National Science Foundation Postdoctoral Fellow also now based at the British Antarctic Survey.


 

 

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 – A Game of Drones (Part 1: A Debris-Covered Glacier)

Image of The Week – A Game of Drones (Part 1: A Debris-Covered Glacier)

What are debris-covered glaciers?

Many alpine glaciers are covered with a layer of surface debris (rock and sediment), which is sourced primarily from glacier headwalls and valley flanks. So-called ‘debris-covered glaciers’ are found in most glacierized regions, with concentrations in the European Alps, the Caucasus, Hindu-Kush-Himalaya, Karakoram and Tien Shan, the Andes, and Alaska and the western Cordillera of North America. Debris cover is important for ice dynamics for several reasons:

  • A layer of surface debris thicker than a few centimetres suppresses ice ablation (Brock et al., 2010), as it insulates the underlying ice from atmospheric heat and insolation.
  • In contrast, a thin layer of debris serves to enhance melt rates through reduced albedo (reflectance) and enhanced heat transfer to underlying ice.
  • A continuous or near-continuous layer of debris can result in debris-covered glaciers persisting at lower elevations than, and attaining lengths which exceed those of their ‘clean ice’ counterparts (Anderson and Anderson, 2016).

Miage Glacier – the largest debris-covered glacier in the European Alps

The Ghiacciaio del Miage, or Miage Glacier, is Italy’s longest glacier and is the largest debris-covered glacier in the European Alps. It is situated in the Aosta Valley, on the southwest flank of the Mont Blanc/Monte Bianco massif. The glacier descends from ~3800 m to ~1700 m above sea level (a.s.l.) across a distance of around 10 km, and is fed by four tributary glaciers. The glacier surface is extensively debris-covered below ~2400 m a.s.l., and the average surface debris thickness is 0.25 m across the lower 5 km of the glacier (Foster et al., 2012).

 

Figure 2: Up-glacier view of Miage Glacier, in which three of the glacier’s four tributaries are visible – from upper centre-left: Tête Carée Glacier, Bionnassay Glacier, Dome Glacier.

Figure 2: Up-glacier view of Miage Glacier, in which three of the glacier’s four tributaries are visible – from upper centre-left: Tête Carée Glacier, Bionnassay Glacier, Dome Glacier.

Glacier surveying using Unmanned Aerial Vehicles

Researchers from Northumbria University, UK, acquired these images of the glacier using a lightweight unmanned aerial vehicle (UAV) during a recent field visit to Miage Glacier. During the visit the team carried out a range of activities including the installation and maintenance of a network of weather stations and temperature loggers across the glacier and geomorphological surveying of the glacier and its catchment, whilst undergraduate students collected data for their final-year research projects. The UAV imagery reveals the emergence of surface debris cover from beneath winter snow cover and the persistence of a channelized hydrological network in the snowpack, characterised as a cascade of streams and storage ponds. A recent study by Fyffe et al. (2015) found that high early-season melt rates and runoff concentration in intermoraine troughs promotes the development of a channelized subglacial hydrological system in mid-glacier areas, whilst the drainage system beneath continuously debris-covered areas down-glacier is largely inefficient due to lower melt inputs and hummocky topography.

(Edited by Emma Smith and Sophie Berger)


Matt Westoby is a postdoctoral researcher at Northumbria University, UK. He is a quantitative geomorphologist, and uses novel high-resolution surveying technologies including repeat UAV-based Structure-from-Motion to quantify surface processes and landscape evolution in glacial and ice-marginal environments. Fieldwork on the Miage Glacier in June 2016 was supported in part by an Early Career Researcher Grant from the British Society for Geomorphology. He tweets as @MattWestoby Contact e-mail: mjwestoby@gmail.com

Image of the Week – Canyons Under The Greenland Ice Sheet!

Image of the Week – Canyons Under The Greenland Ice Sheet!

The Greenland Ice Sheet contains enough water to raise sea level by 7.36 meters (Bamber, et. al. 2013) and much of this moves from the interior of the continent into the oceans via Jakobshavn Isbræ – Greenland’s fastest flowing outlet glacier. An ancient river basin hidden beneath the Greenland Ice Sheet, discovered by researchers at the University of Bristol, may help explain the location, size and velocity of the modern Jakobshavn Isbræ. This Research also provides an insight into what past river drainage may have looked like in Greenland, and what it could look like in the future as the ice sheet retreats exposing more of the land underneath it.


Why?

The topography (i.e. shape) of the bedrock underneath the Greenland Ice Sheet exerts  a strong control on glacier ice flow , particularly  the direction  and velocity of ice flow. It also influences the  distribution of water and sediment  beneath the ice (see here for one reason why this is important). As well as this, studying the shape of the bed can provide a window into the past, to  help understand  historical  erosive processes, which allow scientists to understand the long-term evolution of the landscape, sometimes  they can even look back at what the land may have looked like before it was covered in ice. Building up this kind of picture allows researchers to  assess the interaction between the Greenland Ice Sheet and its bed and how this has evolved over great time-scales, which will further understanding of  how the ice dynamics have changed over time and what this might mean for the future.

How?

As ice is mostly transparent to radio waves at certain frequencies, scientists can use ‘ice-penetrating radar,’ either from aircraft or on the ground, to measure ice thickness as the radio waves bounce back off the bedrock. Data of this kind have been collected over several decades by research teams across the world, with more recent missions being headed by NASA (through Operation Ice Bridge). Using these data, bedrock elevation maps have been produced for both Antarctica, and Greenland allowing researchers to interpret individual features and landscapes hidden beneath the ice.

What have they found beneath the ice?

Recent research has found large channels, or ‘canyons,’ present underneath both the ice sheets of Greenland and Antarctica (e.g. Bamber, et al. 2013; Jamieson, et al. 2016), and our image of this week adds to this picture of dramatic topography underneath the Greenland Ice Sheet (Figure 1). A huge ancient basin has been discovered in southern Greenland, showing signs of being carved by ancient rivers, prior to the extensive glaciation of Greenland (i.e. before the Greenland Ice Sheet existed), rather than being carved by the movement of ice itself. The size of the drainage basin the team discovered is very large, at around 450,000 km2, and accounts for about 20% of the total land area of Greenland (including islands). This is comparable to the size of the Ohio River drainage basin, which is the largest tributary of the Mississippi – or roughly twice the size of Great Britain. The channels the team mapped could more appropriately be called ‘canyons’, with relative depths of around 1,400 metres in places, and nearly 12 km wide, all hidden underneath the ice (Figure 2).

Figure 2: Ice-penetrating radargram cross-sections of some channels within the flow network, showing the size of the features hidden beneath the ice. The bed and surface have been identified: The dashed red line, shows bedrock depth relative to the ice surface, (the solid purple line). There is an exaggeration in the vertical by a factor of 13.

Figure 2: Ice-penetrating radargram cross-sections of some channels within the flow network, showing the size of the features hidden beneath the ice. The bed and surface have been identified: The dashed red line, shows bedrock depth relative to the ice surface, (the solid purple line). There is an exaggeration in the vertical by a factor of 13.

Take Home Message

As well as the basin being an interesting discovery of great size, the channel network and basin appears to be instrumental in influencing the flow of ice from the deep interior to the margin, both now and over several glacial cycles, and in particular controlling the location and speed of the Jakobshavn ice stream, which drains a huge amount of the Greenland Ice Sheet into the oceans. This discovery helps us to better understand why this area of Greenland contains such fast flowing ice and how this might evolve in the future.

For more details of this study check out the full paper:

Cooper, M. A., K. Michaelides, M. J. Siegert, and J. L. Bamber (2016), Paleofluvial landscape inheritance for Jakobshavn Isbræ catchment, Greenland, Geophys. Res. Lett., 43, doi:10.1002/2016GL069458.

(Edited by Emma Smith)


head_shot_mikeMichael Cooper is a PhD Student at the University of Bristol, UK. He Investigates what lies beneath the Greenland ice sheet using airborne ice-penetrating radar, to help further understanding of the inter-relationship between ice and the bed with reference to both contemporary and past ice dynamics. He tweets from @macooperr

Marine Ice Sheet Instability “For Dummies”

Marine Ice Sheet Instability “For Dummies”

MISI is a term that is often thrown into dicussions and papers which talk about the contribution of Antarctica to sea-level rise but what does it actually mean and why do we care about it?

MISI stands for Marine Ice Sheet Instability. In this article, we are going to attempt to explain this term to you and also show you why it is so important.


Background

The Antarctic Ice Sheet represents the largest potential source of future sea-level rise: if all its ice melted, sea level would rise by about 60 m (Vaughan et al., 2013). According to satellite observations, the Antarctic Ice Sheet has lost 1350 Gt (gigatonnes) of ice between 1992 and 2011 (1 Gt = 1000 million tonnes), equivalent to an increase in sea level of 3.75 mm or 0.00375 m (Shepherd et al., 2012). 3.75 mm does not seem a lot but imagine that this sea-level rise is evenly spread over all the oceans on Earth, i.e. over a surface of about 360 million km², leading to a total volume of about 1350 km³, i.e. 1350 Gt of water… The loss over this period is mainly due to increased ice discharge into the ocean in two rapidly changing regions: West Antarctica and the Antarctic Peninsula (Figure 1, blue and orange curves respectively).

Figure 1: Cumulative ice mass changes (left axis) and equivalent sea-level contribution (right axis) of the different Antarctic regions based on different satellite observations (ERS-1/2, Envisat, ICESat, GRACE) from 1992 to 2011 (source: adapted from Fig. 5 of Shepherd et al., 2012 ) with addition of inset: Antarctic map showing the different regions ( source )

What are the projections for the future?

Figure 2: Ice velocity of the glaciers in the Amundsen Sea Embayment, West Antarctica, using ERS-1/2 radar data in winter 1996. The grounding line (boundary between ice sheet and ice shelf) is shown for 1992, 1994, 1996, 2000 and 2011 (source: Fig. 1 of Rignot et al., 2014 ).

Figure 2: Ice velocity of the glaciers in the Amundsen Sea Embayment, West Antarctica, using ERS-1/2 radar data in winter 1996. The grounding line (boundary between ice sheet and ice shelf) is shown for 1992, 1994, 1996, 2000 and 2011 (source: Fig. 1 of Rignot et al., 2014 ).

According to model projections from the Intergovernmental Panel on Climate Change (IPCC), global mean sea level will rise by 0.26 to 0.82 m during the twenty-first century (Church et al., 2013). The contribution from the Antarctic Ice Sheet in those projections will be about 0.05 m (or 50 mm) sea-level equivalent, i.e. 10% of the global projected sea-level rise, with other contributions coming from thermal expansion (40 %), glaciers (25 %), Greenland Ice Sheet (17 %) and land water storage (8 %).

The contribution from Antarctica compared to other contributions does not seem huge, however there is a high uncertainty coming from the possible instability of the West Antarctic Ice Sheet. According to theoretical (Weertman, 1974; Schoof, 2007) and recent modeling results (e.g. Favier et al., 2014; Joughin et al., 2014), this region could be subject to marine ice sheet instability (MISI), which could lead to considerable and rapid ice discharge from Antarctica. Satellite observations show that MISI may be under way in the Amundsen Sea Embayment (Rignot et al., 2014), where some of the fastest flowing glaciers on Earth are located, e.g. Pine Island and Thwaites glaciers (Figure 2). So what exactly is MISI?

What is marine ice sheet instability (MISI)?

 

Figure 3: Antarctic map of ice sheet (blue), ice shelves (orange) and islands/ice rises (green) based on satellite data (ICESat and MODIS). The grounding line is the separation between the ice sheet and the ice shelves. Units on X and Y axes are km (source: NASA ).

Figure 3: Antarctic map of ice sheet (blue), ice shelves (orange) and islands/ice rises (green) based on satellite data (ICESat and MODIS). The grounding line is the separation between the ice sheet and the ice shelves. Units on X and Y axes are km (source: NASA ).

To understand the concept of MISI, it is important to define both ‘marine ice sheet’ and ‘grounding line’:

 

  • A marine ice sheet is an ice sheet sitting on a bedrock that is below sea level, for example the West Antarctic Ice Sheet.
  • The grounding line is the boundary between the ice sheet, sitting on land, and the floating ice shelves (Figure 3 for a view from above and Figure 4 for a side view). The position and migration of this grounding line control the stability of a marine ice sheet.

 

 

The MISI hypothesis states that when the bedrock slopes down from the coast towards the interior of the marine ice sheet, which is the case in large parts of West Antarctica, the grounding line is not stable (in the absence of back forces provided by ice shelves, see next section for more details). To explain this concept, let us take the schematic example shown in Figure 4:

  1. The grounding line is initially located on a bedrock sill (Figure 4a). This position is stable: the ice flux at the grounding line, which is the amount of ice passing through the grounding line per unit time, matches the total upstream accumulation.
  2. A perturbation is applied at the grounding line, e.g. through the incursion of warm Circumpolar Deep Water (CDW, red arrow in Figure 4) below the ice shelf as observed in the Amundsen Sea Embayment.
  3. These warm waters lead to basal melting at the grounding line, ice-shelf thinning and glacier acceleration, resulting in an inland retreat of the grounding line.
  4. The grounding line is then located on a bedrock that slopes downward inland (Figure 4b), i.e. an unstable position where the ice column at the grounding line is thicker than previously (Figure 4a). The theory shows that ice flux at the grounding line is strongly dependent on ice thickness there (Weertman, 1974; Schoof, 2007), so a thicker ice leads to a higher ice flux.
  5. Then, the grounding line is forced to retreat since the ice flux at the grounding line is higher than the upstream accumulation.
  6. This is a positive feedback and the retreat only stops once a new stable position is reached (e.g. a bedrock high), where both ice flux at the grounding line and upstream accumulation match.
Figure 4: Schematic representation of the marine ice sheet instability (MISI) with (a) an initial stable grounding-line position and (b) an unstable grounding-line position after the incursion of warm Circumpolar Deep Water (CDW) below the ice shelf (source: Fig. 3 of Hanna et al., 2013 ).

Figure 4: Schematic representation of the marine ice sheet instability (MISI) with (a) an initial stable grounding-line position and (b) an unstable grounding-line position after the incursion of warm Circumpolar Deep Water (CDW) below the ice shelf (source: Fig. 3 of Hanna et al., 2013 ).

  • In summary, the MISI hypothesis describes the condition where a marine ice sheet is unstable due to being grounded below sea level on land that is sloping downward from the coast to the interior of the ice sheet.
  • This configuration leads to potential rapid retreat of the grounding line and speed up of ice flow from the interior of the continent into the oceans.

Is there evidence that MISI is happening right now?

 

Figure 5: Buttressing provided by Larsen C ice shelf, Antarctic Peninsula, based on a model simulation (Elmer/Ice). Buttressing values range between 0 (no buttressing) and 1 (high buttressing). The red contour shows the buttressing=0.3 isoline. Observed ice velocity is also shown (source: Fig. 2 of Fürst et al., 2016 ).

Figure 5: Buttressing provided by Larsen C ice shelf, Antarctic Peninsula, based on a model simulation (Elmer/Ice). Buttressing values range between 0 (no buttressing) and 1 (high buttressing). The red contour shows the buttressing=0.3 isoline. Observed ice velocity is also shown (source: Fig. 2 of Fürst et al., 2016 ).

In reality, the grounding line is often stabilized by an ice shelf that is laterally confined by side walls (see Figure 5, where Bawden and Gipps ice rises confine Larsen C ice shelf) or by an ice shelf that has a contact with a locally grounded feature (Figure 6). Both cases transmit a back force towards the ice sheet, the ‘buttressing effect’, which stabilizes the grounding line (Goldberg et al., 2009; Gudmundsson, 2013) even if the configuration is unstable, i.e. in the case of a grounding line located on a bedrock sloping down towards the interior (Figure 4b).

 

However, in the last two decades, the grounding lines of the glaciers in the Amundsen Sea Embayment (Pine Island and Thwaites glaciers for example) retreated with rates of 1 to 2 km per year, in regions of bedrock sloping down towards the ice sheet interior (Rignot et al., 2014). The trigger of these grounding-line retreats is the incursion of warm CDW penetrating deeply into cavities below the ice shelves (Jacobs et al., 2011), carrying important amounts of heat that melt the base of ice shelves (Figure 4). Increased basal melt rates have led to ice-shelf thinning, which has reduced the ice-shelf buttressing effect and increased ice discharge. All of this has led to grounding-line retreat. The exact cause of CDW changes is not clearly known but these incursions are probably linked to changes in local wind stress (Steig et al., 2012) rather than an actual warming of CDW.

 

 

Figure 6: Schematic representation of ice-shelf buttressing by a local pinning point (source: courtesy of R. Drews ).

Figure 6: Schematic representation of ice-shelf buttressing by a local pinning point (source: courtesy of R. Drews ).

There is currently no major obstacle to these grounding line retreats. Therefore, the Amundsen Sea Embayment is probably experiencing MISI and glaciers will continue to retreat if no stabilization is reached. This sector of West Antarctica contains enough ice to raise global sea level by 1.2 m.

 

What can we do about it?

MISI is probably ongoing in some parts of Antarctica and sea level could rise more than previously estimated if the grounding lines of the glaciers in the Amundsen Sea Embayment continue to retreat so fast. This could have catastrophic impacts on populations living close to the coasts, for example more frequent flooding of coastal cities, enhanced coastal erosion or changes in water quality.

Thus, it is important to continue monitoring the changes happening in Antarctica, and particularly in West Antarctica. This will allow us to better understand and project future sea-level rise from this region, as well as better adapt the cities of tomorrow.

Edited by Clara Burgard and Emma Smith


DavidDavid Docquier is a post-doctoral researcher at the Earth and Life Institute of Université catholique de Louvain (UCL) in Belgium. He works on the development of processed-based sea-ice metrics in order to improve the evaluation of global climate models (GCMs). His study is embedded within the EU Horizon 2020 PRIMAVERA project, which aims at developing a new generation of high-resolution GCMs to better represent the climate.

Image of the Week — Historical aerial imagery of Greenland

Image of the Week — Historical aerial imagery of Greenland

A few month ago, we were taking you on a trip back to Antarctic fieldwork 50 years ago, today we go back to Greenland during 1930s!

When geopolitics serves cryospheric sciences

The Permanent Court of International Justice in The Hague awarded Danish sovereignty over Greenland in 1933 and besides geopolitical interests, Denmark had a keen interest in searching for natural resources and new opportunities in this newly acquired colony. In the 1930s the Danish Government initiated three comprehensive expeditions; one of these, the systematic mapping of East Greenland, was set off by The Greenlandic Agency, The Marines’ air services, The Army’s Flight troops and Geodetic Institute. The Danish Marines provided pilots, mechanics, and three Heinkel seaplanes.

Danish expeditioner Lauge Koch, centre, along with his pilots all dressed in suits made from polar bear. (Credit: The Arctic Institute)

Danish expeditioner Lauge Koch, centre, along with his pilots all dressed in suits made from polar bear. (Credit: The Arctic Institute)

Aerial photography in the 1930s – practical constraints

The airplanes had three seats in an open cockpit. The pilot was seated in the front, the radio operator in the center and in the back the photographer – this seat was originally for the machine-gun operator.

At the outset, the idea was to take vertical images, but that was impossible at the time due to the height of the mountains and the limited capability of the aircraft to reach adequate heights. The airplanes couldn’t reach more than 4000 m – similar to the height of mountains in Greenland. Oblique images were therefore recorded. The reduced view of the terrain when photographing in oblique angles required many more flights than originally planned. The photographic films were processed immediately after each flight. 45,000 km were covered during the first season, which lasted about two and a half months. In the following years, each summer a flight covered parts of the Greenlandic coast. During the Second World War, the mapping was temporarily stopped due to safety reasons.

The aircraft had an open hole in the floor for the photographer, originally where the machine gunner would sit. (Credit: The Arctic Institute)

The aircraft had an open hole in the floor for the photographer, originally where the machine gunner would sit.(Credit: The Arctic Institute)

An unexplored treasure trove of climate data

The tremendous volume of aerial images obtained from several expeditions and hundreds of flights not only constitutes the cornerstone of mapping in Greenland, but is invaluable data for studying climate change in these remote regions. The 1930s survey, compared to modern imagery, provides crucial insight into coastal changes, ice sheet mass balances, and glacier movement. Glacier fluctuations in southeast Greenland have been identified, showing that many land-terminating glaciers underwent a more rapid retreat in the 1930s than in the 2000s, whereas marine-terminating glaciers retreat more rapidly during the recent warming (Bjørk et al, 2012).

An ongoing project between the University of Copenhagen, INSTAAR (Institute of Arctic and Alpine Research) in Boulder, Colorado, and Natural History Museum of Denmark is currently focusing on analysing deltaic changes in Central and Southern Greenland; linking shoreline development to climate changes – these historic aerial images are essential for detecting such coastal evolution. However, there are still many other links between the past and present climate to be discovered from these images. Interested in hearing more about the project or the aerial images? Please contact Mette Bendixen (mette.bendixen@ign.ku.dk)

Bibliography

Bjørk, A. A., Kjær, K. H., Korsgaard, N. J., Khan, S. A., Kjeldsen, K. K., Andresen, C. S., … & Funder, S. (2012). An aerial view of 80 years of climate-related glacier fluctuations in southeast Greenland. Nature Geoscience, 5(6), 427-432. http://dx.doi.org/DOI:10.1038/ngeo1481

Edited by Alistair McConnell, Sophie Berger and Emma Smith


Mette BendixenMette Bendixen is s a PhD student at the Center for Permafrost in Copenhagen. She investigates the changing geomorphology of Greenlandic coasts, where climate changes can have huge impact on the local environment.

European Space Agency Living Planet Symposium 2016

European Space Agency Living Planet Symposium 2016

Living Planet Symposium

Between the 9th and 13th May, Prague played host to the European Space Agency’s (ESA) fourth Living Planet Symposium. The event, the largest in its history with over 3300 attendees, brought together the earth observation community across multiple disciplines to discuss significant scientific results and the future developments of earth observation missions. Earth Observation  of the Cryosphere over the last few decades has revolutionised our understanding of these regions, allowing us to monitor and assess ice sheet dynamics at unprecedented spatial and temporal scales.

ESA & Observation of the Cryosphere

The role of Earth Observation in Cryospheric sciences is set to increase further thanks to the European Commission and ESA Copernicus program; a series of satellites called Sentinels which all feature different sensor instrumentation, allowing researchers to monitor various aspects of the Earth System. The program will consist of 6 separate sentinel missions and will allow us to measure various Ice Sheet and Glacier dynamics continuously at a high temporal resolution. In addition, the Earth Explorer mission CryoSat-2 has been transforming our knowledge of the polar regions since it’s launch in 2010.

As a result, the conference had a wide range of exciting scientific results related to the Cryosphere from these missions; ranging from data products to be used by the community to the exploitation of mission data to further our knowledge of key processes and outstanding scientific questions.

Don’t worry if you weren’t able to make the symposium, as this post will highlight a selection of interesting results and the impact they will have on Cryospheric research!

CryoSat-2: Transforming Knowledge of the Cryosphere

CryoSat-2, an ESA Earth Explorer satellite that carries onboard a radar altimeter to measure ice elevation (Credit : ESA – P. Carril)

CryoSat-2, an ESA Earth Explorer satellite that carries onboard a radar altimeter to measure ice elevation (Credit : ESA – P. Carril)

CryoSat-2 is the ESA Earth Explorer radar altimetry mission dedicated to monitoring changes in surface elevation of earth’s ice sheets, sea-ice thickness and extent; which it has been routinely monitoring since November 2010. The combination of its unique polar orbital characteristics and novel dual antenna interferometric mode of operation has allowed it to overcome  many of the issues associated with previous altimetry missions over ice sheets.

Major results from CryoSat-2 included the application of swath processing techniques to the interferometric data to dramatically increase the number of surface elevation measurements available to researchers (Gray et al, 2013). Traditionally, the radar instrumentation would record a single elevation measurement at the point of closest approach (POCA) to the satellite. However, this technique analyses the whole radar return to produce measurements across the satellite footprint. By exploiting this increased data density it allows researchers to investigate ice sheet changes at much finer spatial and temporal resolution, allowing for an increase in the range of scientific questions the satellite is able to address. Examples of this include glacier thinning as a result of surging events that have previously occurred on time scales not possible to be captured by the satellite. It will also allow us to get a more complete picture of mass balance using the altimetry method.

Ice-shelf thickness in Antarctica

Furthermore, a contemporary continental ice shelf thickness dataset (Chuter and Bamber, 2015) derived from CryoSat-2 was presented; which provides large accuracy improvements over the previous ERS-1 derived dataset (Griggs and Bamber, 2011), particularly in the grounding zone, a key region for monitoring ice sheet stability. The results from this work will allow the community to improve accuracy in mass balance estimations from the input-output method, sub-ice shelf ocean modelling and for parameterisations in ice sheet models.

Ish_thick

Antarctic ice shelf thickness Derived from CryoSat-2 radar altimetry (Credit: subset of fig S1 from Chuter and Bamber, 2015). 

Monitoring sea ice

Sea ice monitoring is also a key mission objective, with the satellite already delivering on these aims through studies of continuous monitoring of the Arctic Sea Ice over the past five years.  Work presented at the symposium by Rachel Tilling (CPOM/University College London) makes use of the Near Real Time data products from ESA to deliver knowledge of sea ice thickness and extent as quick as two days after data acquisition, providing benefits to the shipping industry in addition to aiding arctic climate predictions (see also Tilling et al, 2015).

Antarctic mass balance

For the Antarctic ice sheet, mass balance estimates obtained from altimetry, gravimetry, and mass-budget methods can yield conflicting results with error bars that do not always overlap.

Some of these techniques use models to isolate and remove the effects of glacio-isostatic adjustment and surface mass balance (SMB) processes,  introducing another source of uncertainty which is hard to quantify.

a) Estimates of mass balance for the Amundsen Sea Embayment (ASE) sector in Antarctica from different techniques, including estimates from the RATES project. b) Estimates of the mass loss due to ice dynamics (red) and SMB (blue) for the ASE, compared with modeled values from RACMO2.3 (red dots) and ice discharge (blue line) (Credit: fig 9a from Martín-Español, et al. 2016)

a) Estimates of mass balance for the Amundsen Sea Embayment sector in West Antarctica from different techniques, including estimates from the RATES project. [IOM = Input-Output Method] b) Estimates of the mass loss due to ice dynamics (red) and Surface Mass Balance (SMB — blue) for the Amundsen Sea Sector, compared with modeled values from RACMO2.3 (red dots) and ice discharge (D — blue line) (Credit: fig 9 from Martín-Español et al. 2016)

To address both these issues, the RATES project presented a statistical modelling approach to the problem (Martin-Español et al., 2016). They combined the observational data (including satellite altimetry, GRACE, GPS and InSAR), and used prior information to separate out the mass balance signal into its main components.  For instance, we know that the glacio-isostatic adjustment has a large spatial length-scale, but  changes in ice dynamics may vary from one glacier to the next. We thus can `look’ for these components within the data and attribute them to the correct process. For the period 2003-2013, they estimated a mean mass balance rate of -82±23 Gt/yr with a sustained negative mean trend of dynamic imbalance to which West Antarctica is the largest contributor, mainly triggered by high thinning rates of glaciers draining into the Amundsen Sea Embayment. The Antarctic Peninsula has experienced a dramatic increase in mass loss in the last decade following the destabilization of the Southern Antarctic Peninsula. The total mass loss is partly compensated by a significant mass gain in East Antarctica due to a positive trend of SMB anomalies.

4th Cryosat User workshop

In addition to major scientific results and products, the conference combined with the 4th CryoSat User Workshop, bringing together users from all cryospheric disciplines to discuss a variety of issues such as: Product Calibration and Validation campaigns, future data product releases and further serving the needs of the scientific community. In addition, with the satellite currently being operated beyond in it’s initial commissioning timespan, initial discussions were held regarding whether there would be the possibility of a follow up and the form it could possibly take.

Sentinel 1A/B – A New Era for Ice sheet Velocity Mapping

sentinel

Sentinel 1A/B is the Copernicus Synthetic Aperture Radar (SAR) mission, providing global radar imagery currently at a 12 day repeat period, free from the limitations posed by multispectral imagery such as cloud cover. The launch of Sentinel 1B on the 25th April this year to join in constellation with 1A will reduce this repeat period to 6 days. This will allow for continuous, long term monitoring of the Earth’s Cryosphere at a high temporal resolution.

Sentinel 1 results presented at the conference exemplified the transformative power this mission will have on Cryospheric sciences. Firstly, it will allow us to produce continental velocity maps for both Greenland and Antarctica at sub-annual resolution. This will allow for monitoring of seasonal velocity changes in outlet glaciers, better estimations of mass balance and improved parameterisations of conditions in ice sheet models.  Additionally, the mission is now providing researchers with a near real time data stream of ice velocities for key outlets of the Greenland and Antarctic ice sheets, allowing them to track changes and investigate changes in behaviour at 12-day scale (reducing to 6 days with 1B) (Hogg et al, 2016).

Ice Sheet velocity across the Antarctic peninsula derived from Sentinel 1 data from December 2014 to March 2016. Image Credit ESA and ENVEO: http://www.esa.int/spaceinimages/Images/2016/05/Antarctic_Peninsula_ice_flow

Ice Sheet velocity across the Antarctic peninsula derived from Sentinel 1 data from December 2014 to March 2016. (Credit: ESA and ENVEO)

The grounding line is a key region of the ice sheet to monitor due to it’s ability to indicate changes in the dynamics of the inland Ice Sheet and it’s potential instability. SAR missions allow us to map the grounding line with high accuracy by analysing the differences in vertical tidal displacement of the ice shelves between images via the formation of interferograms. Previously there has been discontinuous temporal coverage from various SAR missions; however with the advent of Sentinel 1 mission, it will possibly to routinely monitor grounding line flux position for an extended period of time, improving our understanding of key ice sheet processes and inland grounded ice stability.

Final Thoughts

The conference showed us the combined power offered by the new Sentinel missions and the continuation of CryoSat-2 in allowing us to monitor the Cryosphere at scales not previously possible, thus shedding more light on the dynamics of these key earth system regions. The new satellites have allowed researchers to produce new and improved datasets open for use by the scientific community, helping to accelerate and enable future discoveries. Additionally, when these datasets are used in combination, they can help us to better answer some of the subject’s biggest questions; such as the mass balance of the Ice Sheets and its changes over time. As a result, these missions promise for exciting times ahead in terms of greatly forwarding our understanding of the Cryosphere.

 With the new sentinel missions and the continuation of CryoSat-2 exciting times are ahead for remote sensers of the cryosphere

Aside from the Conference – City of Prague

Prague offered many sights and opportunities to explore during the downtime of the conference. Highlights of the City included the Charles Bridge built in 1390 and the old Town Square which hosts the famous astronomical clock. All of this is set to the backdrop of Prague Castle, the largest ancient castle in the world and residence of the President of the Czech Republic. The City also has a famous classical music and opera scene and offers some of the world’s best beer, providing the perfect opportunity to network and make contacts!


References

  • Chuter, S. J., and J. L. Bamber (2015), Antarctic ice shelf thickness from CryoSat-2 radar altimetry, Geophys. Res. Lett., 42(24), 10,721–10,729, doi:10.1002/2015GL066515.
  • Gray, L, D Burgess, L Copland, R Cullen, N Galin, R Hawley, and V Helm. 2013. “Interferometric Swath Processing of Cryosat Data for Glacial Ice Topography.” The Cryosphere 7 (6). Copernicus GmbH: 1857–67.
  • Griggs, J.A., and J.L. Bamber. 2011. “Antarctic Ice-Shelf Thickness from Satellite Radar Altimetry.” Journal of Glaciology 57 (203). International Glaciological Society: 485–98. doi:10.3189/002214311796905659.
  • Hogg, A., A. Shepherd, N. Gourmelen (2015) A first look at the performance of Sentinel-1 over the West Antarctic Ice Sheet, FRINGE 2015, Frascati, Italy, 23-27 March 2015.
  • Martín-Español, A. et al. (2016), Spatial and temporal Antarctic Ice Sheet mass trends, glacio-isostatic adjustment and surface processes from a joint inversion of satellite altimeter, gravity and GPS data, J. Geophys. Res. Earth Surf., 120, 1–18, doi:10.1002/2015JF003550.
  • Tilling, R. L., A. Ridout, A. Shepherd, and D. J. Wingham (2015), Increased Arctic sea ice volume after anomalously low melting in 2013 – supplementary Information, Nat. Geosci., 8(8), 643–646, doi:10.1038/ngeo2489.

Edited by Sophie Berger


steve

Stephen Chuter is a PhD Student at the University of Bristol, UK. He  Investigates the dynamics of the Antarctic Ice Shelves and grounding zone using the ESA CryoSat-2 satellite. The unique orbital characteristics and novel SARIn mode of operation allow us to study these areas in much greater detail than possible from previous radar altimetry missions, therefore allowing us to greater ascertain its role in ice sheet stability. He tweets as @StephenChuter.
Contact Email: s.chuter@bristol.ac.uk

 

From Hot to Cold – Volcanology Meets the Cryosphere

From Hot to Cold – Volcanology Meets the Cryosphere

Hello again, I’m Kathi Unglert, and you’re about to read my third and final post as a student reporter at EGU 2016. Today I am writing about my experience in the cryosphere sessions from my volcanology perspective.


In preparation for the conference I kept thinking about what sort of research I would see in the cryosphere sessions. I had never really attended any specific conferences or meetings on the topic, so most of what I knew was from work that friends of mine do, which is mainly ice stream modelling. I am wondering whether similar tools (for example, analytical or numerical methods) can be used to model ice streams and lava flows?

 

A Tale of Ice and Fire

Thinking about the differences between ice streams/glaciers and lava, another potential overlap between cryospheric sciences and volcanology jumps out; In places like Iceland, volcanoes sometimes sit underneath large ice sheets. Similarly, tall volcanoes – particularly those in high mountain ranges – are often covered in snow and have small glaciers in their craters or on their summits. It is important to understand the interactions between the warm volcano, the hot lava, and the cold ice. For example, to forecast catastrophic floods that often occur when a subglacial volcanic eruption melts parts of the overlying ice and snow (so-called “jökulhlaups”). There is even a commission on “glaciovolcanism”, and it turns out that astrogeologists are quite interested in the topic to learn more about potential volcano-ice interactions on Mars. I had no idea how interdisciplinary this field of research was. It would definitely be useful for volcanologists to poke their heads into cryosphere meetings once in a while, and vice versa. Throw a little bit of planetary science in the mix, and you have a textbook example of interdisciplinary research!

Lava meets snow: Lava flowing into a canyon at the snow covered Eyjafjallajökull during an eruption in 2010 - one of the many examples where volcanology and cryospheric sciences meet. Photo credit: Martin Hensch (Imaggeo)

Lava meets snow: Lava flowing into a canyon at the snow covered Eyjafjallajökull during an eruption in 2010 – one of the many examples where volcanology and cryospheric sciences meet. Photo credit: Martin Hensch (Imaggeo)

The methods that we use in the different fields can also be quite similar: Resistivity measurements can be used to determine the extent of permafrost in the subsurface in Artic regions, but also to detect high temperature bodies beneath volcanic edifices that may be storing magma. I also saw a PICO presentation at the conference last week that uses cosmic rays to image the bed of a glacier in the Swiss Alps, a technique that volcanologists have tested to detect magma reservoirs and conduits on volcanoes!

In terms of the bigger picture, volcanological and cryospheric research overlap a lot in climatology. Erupting volcanoes emit gases and increase aerosols in the atmosphere, which can affect the climate locally, regionally, or even globally. The traces of such volcanic eruptions can sometimes be found in ice cores, where volcanic ash gets trapped and preserved for centuries or more. For a long time, it has been known that at least one big volcanic eruption in the 6th century – the traces of which have been found in ice cores – caused strong changes in climate for a few years, and some studies suggest that these effects may have contributed to political and societal instability in the Maya civilization in Central America at the same time. There was even a press conference about it at the EGU 2016 meeting. Other questions that we could ask might be “Does wide spread glaciation change the frequency or nature of volcanic eruptions?”, “How do volcanic eruptions affect the climate and ice stream or glacier dynamics?”, or “What can we learn about glacier dynamics by analyzing the locations of volcanic deposits in ice?”

So you know how they say “go big or go home”? Let’s put our minds together and get interdisciplinary! At the very least it’s going to be fun to think in slightly different terms for a while, and who knows where it may lead!

 

The EGU Student Reporter Experience

All in all, it’s been really great taking part in the Student Reporter Programme, and peeking into a totally different field. Seeing overlap between the different disciplines was a good experience, and one that was made possible by being a student reporter. Sometimes we get so stuck in our individual little niche that there is no room for anything else, despite the fact that other disciplines might have come across the same problems, struggled with the same methods, and maybe found a solution. I was lucky that the session schedule worked out ok – most days when things were a bit slow volcanology-wise I was able to go a cryosphere session. However, that way it was a very busy week, there was rarely ever any downtime, or time away from the conference. During the few quiet moments I spent time in the press office, doing some background research for my posts, editing work from the other reporters, or going to a press conference. I have to say, the press office was a new, but very cool experience. There were always interesting people around, both scientists presenting their latest results and journalists trying to find a new story. I’ve been into science writing for a while, so meeting some of the people whose work I read was a really cool bonus to the whole programme! If you enjoy writing, don’t mind a faster pace, and are curious about science at EGU outside your field I would highly recommend the Student Reporter Programme. If there is no blog in your discipline (like it was the case for me) that might even be a good thing, and you’ll get to learn some new and unexpected things!

(Edited by Emma Smith and Sophie Berger)


 

profile_highres_EarthMatters_lightKathi Unglert is a PhD student in volcanology at the University of British Columbia, Vancouver. Her work looks at volcanic tremor, a special type of earthquake that tends to happen just before or during volcanic eruptions. She uses pattern recognition algorithms to compare tremor from many volcanoes to identify systematic similarities or differences. This comparison may help to determine the mechanisms causing this type earthquake, and could contribute to improved eruption forecasting. You can find her on Twitter (@volcanokathi) or read her volcano blog.

 

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