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Cryospheric Sciences

Cryospheric Sciences

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

Image of The Week – When Glaciers Fertilize Oceans

Image of The Week – When Glaciers Fertilize Oceans

Today’s Image of the Week shows meltwaters originating from Leverett Glacier pouring over a waterfall in southwest Greenland. We have previously reported on how meItwater is of interest to Glaciologist (e.g. here) but today we are going to delve into how and why Biologists also study these meltwaters and how the cryosphere interacts with biogeochemical cycles in our oceans.

Figure 2: Location of Leverett Glacier. The glacier drains an area of 600 km2 of the Greenland Ice Sheet. Adapated from Hawkings et al. (2014) .

Where?

Leverett Glacier of the Greenland ice sheet (Fig. 2) discharges around 2 km3 of water a year from its 600 km2 catchment area. This single meltwater river has previously reached 800 m3 sec-1 at peak flow in the summer (in 2012; for contrast the Danube average flow is roughly 2000 m3 sec-1 as it passes through Budapest). These meltwaters are sediment rich and occur not just at Leverett but at hundreds of glaciers across the Greenland ice sheet, dumping a total of more than 400 billion tons of water in the oceans each year; a number than has risen steeply in recent years due to the rapidly warming Arctic climate. Relatively little is known about how this large seasonal input of glacial water may impact ocean life.

How?

Over the past few years fieldwork teams have visited Leverett Glacier each season to give us an insight into the importance of the Greenland ice sheet in supplying ecosystems with nutrients. To address this question they collect lots of water and sediment samples to analyse (using special instrument back in labs at The Universities of Bristol, Southampton and Leeds) and install semi-permanent sensors to see what’s happening to the river in real time (Fig 3).

These sensors record water temperature, depth, sediment concentrations and the amount of dissolved solids. This comprehensive dataset has provided a really nice picture of the system and the changes occurring at a high temporal resolution. They have also been testing cutting edge sensor technologies to measure things like nitrate and methane in the water more recently and, of course, they took some great drone footage of their work.

Figure 3: Semi-permanent sensor monitoring water temperature, depth, sediment concentrations and the amount of dissolved solids in glacial meltwaters from Leverett Glacier, Greenland (credit: Jon Hawkings).

Figure 3: Semi-permanent sensor monitoring water temperature, depth, sediment concentrations and the amount of dissolved solids in glacial meltwaters from Leverett Glacier, Greenland (credit: Jon Hawkings).

What’s Happening?

These studies have found that glaciated regions, such as Greenland, are likely to be dumping large quantities of nutrients such as phosphorus, iron and silica into the polar oceans, feeding life at the bottom of the food chain and contributing to ecosystem health. This challenges the traditional view that ice sheets are relatively unimportant in biogeochemical cycles compared to other terrestrial environments.

Glaciers are like giant bulldozers crushing rock into finely ground rock dust as they move – it is this dust that give glacial meltwaters their milky colour. Water flowing below the ice, dissolves the minerals in the freshly crushed rock and transports them out into the oceans. These minerals provide nutrients that act as a fertilizer for ocean life – phytoplankton, the microscopic plants of the ocean, need rock derived nutrients to grow. These little guys are really important for the health of our planet. They form the base of the ocean food chain, and photosynthesise thus potentially capturing CO2 from the atmosphere. As glaciated regions like Greenland dump more meltwater into the oceans it is possible more nutrients could also be delivered, although more research needs to be conducted to ascertain if this is the case.

Want to find out more?

  • Hawkings et al. (2014) Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans, Nature Communications, 5.
  • Lawson et al. (2014) Greenland Ice Sheet exports labile organic carbon to the Arctic oceans, Biogeosciences, 11(14): 4015-4028.
  • Hawkings et al. (2015) The effect of warming climate on nutrient and solute export from the Greenland Ice Sheet, Geochemical Perspectives Letters, 1: 94-104
  • Hawkings et al. (2016) The Greenland Ice Sheet as a hotspot of phosphorus weathering and export in the Arctic, Global Biogeochemical Cycles, 30: 191-210

Edited by Emma Smith


About Jon Hawkings:

Jon Hawkings is a post-doctoral research associate at the School of Geographical Sciences, in the University of Bristol. His research focuses on the biogeochemistry of the coldest areas of our planet. Specifically he is looking at the impact that melting ice sheets may be having on downstream and marine ecosystems. He enjoys working in some of the most inhospitable and challenging environments – pretty much all of his data stems from samples collected in the field. He tweets as @jonnyhawkings.

Image of the Week – Monitoring icy rivers from space!

Image of the Week – Monitoring icy rivers from space!
Ice and floodwater inundate a town in Alaska because an ice jam formed downstream (credit: U.S. National Park Service on Wikimedia Commons)

Ice and floodwater inundate a town in Alaska because an ice jam formed downstream (credit: U.S. National Park Service)

Why?

When a river freezes over, it changes the amount of water that flows through the river system. River ice affects many of the world’s largest rivers, and in the Northern Hemisphere, approximately 60% of rivers experience significant seasonal effects. The formation and evolution of river ice changes river discharge and is not only of interest to local ice skating enthusiasts. The variations in river discharge can lead to severe situations, such as ice jams/dams (with an accompanying risk of flooding), or issues that affect the management of hydroelectric power plant infrastructures.

How?

Satellite data have a huge potential for river ice monitoring thanks to the capability of imaging large areas. Synthetic Aperture Radar (SAR) systems are particularly promising as they can acquire data day or night without regard to cloud cover. In this way the extent of river ice can be mapped in great detail. The image of this week was produced applying one specific SAR technique : the polarimetry.

What?

The image of this week is a false color composite with the different polarimetric channels (red = HH, green = HV and blue = VV) of RADARSAT-2 images. The nature of the ground/ice surface will influence the way the waves sent by the radar interact with it and thus the value of the backscattered signal in different polarisation. The pattern on the left image was then introduced in an algorithm to automatically retrieve different types of ice (right image). Recognising ice types from space is an essential step to monitor and then predict processes such as ice dam collapses.

Los_Vistula_river-ice-illustration_typesjpg

Photo-interpretation key of the different types of ice, after Pawłowski et al (2015)

Reference

Pawłowski B., Łoś H., Osińska-Skotak K. (2015) The first approach of ice filling and river ice cover types classification for the lower Vistula River based on satellite SAR data. Monografie Komisji Hydrologicznej PTG ; t. 3, pp. 313-324.

Also check out:

This previous image of the week on SAR polarimetry applied to sea ice

The image of last week about another type of ice dam, at the terminus of a glacier

Image of The Week – That’s a Damn Fine Ice Dam!

Image of The Week – That’s a Damn Fine Ice Dam!

With today’s image of the week we want to transport you to Patagonia to look at a unique fresh-water calving glacier –  Perito Moreno in Argentina. This is a hot topic at the moment as the glacier did something rather unusual yesterday, read on to find out more…..

This large glacier (Fig 2, highlighted red) flows down a valley, calving into the southwestern arm of Lago Argentino  at its terminus. However, at times the glacier front advances far enough to connect with land on the opposite bank of Lago Argentino. This cuts off the flow of water from Brazo Rico (Fig 1., left), into Lago Argentino (Fig 1., right) acting as an ice dam.

Figure 2: Landsat 5 image (Mar. 21, 2001) showing Glacier Perito Moreno (red) and the surrounding area. Adapted from Naruse and Skvarca, 2012 .

Figure 2: Landsat 5 image (Mar. 21, 2001) showing Glacier Perito Moreno (red) and the surrounding area. Adapted from Naruse and Skvarca, 2012 .

The ice dam can reach hundreds of meters in height and can cause the water level in Brazo Rico to rise up to 30 m above that of Lago Argentino. Eventually the dam collapses, accompanied by rapid collapse of the ice front and the water rushes through, equalising water levels. The glacier then continues to advance and the cycle repeats.

These collapse events appear to happen every few years, with the last event happening YESTERDAY – March 10th 2016 (see the video link). The length of a cycle is very unpredictable and it is unclear exactly what is controlling the ice dynamics in this region. Naruse and Skvarca, 2012 made a comprehensive study of the 2003-2004 ice dam formation and collapse but more information is needed to fully understand this complex glacier.

Edited by Sophie Berger and Nanna Karlsson

Image of the Week — Last Glacial Maximum in Europe

Image of the Week — Last Glacial Maximum in Europe

During the last ice age*, ~70,000 to 20,000 years ago, the climate was much colder in Europe.

As a result, the northern part of Europe was fully covered by the Fennoscandian (a.k.a the Scandinavian ) ice sheet, which extended up to the British Isles and some parts of Poland and Germany. In central Europe, the Alps were also almost fully glaciated.

The storage of all this ice on the continent lowered the sea level (seedark green), which substantially reduced the extent of the North Sea.

*This period is referred to as the Weichselian glaciation and the Würm glaciation in Northern Europe and the Alps, respectively.

 

More information

A more complete and accurate dataset (including GIS maps) of Europe during the last glacial maximum is freely available :

Becker, D., Verheul, J., Zickel, M., Willmes, C. (2015): LGM paleoenvironment of Europe – Map. CRC806-Database, DOI: http://dx.doi.org/10.5880/SFB806.15

LGM_Europe_Map_v1

 

Image of the Week – Antarctic fieldwork 50 years ago!

Image of the Week – Antarctic fieldwork 50 years ago!

So far this blog has published many pictures of current polar field work campaigns. Today, we would like to take you back to Antarctic expeditions during the 1960s. The photos presented in this post date back from the Belgian-Dutch Antarctic field campaigns of 1964-1966.

The first picture shows Ken Blaiklock (red overalls) with a Belgian surveyor. Ken was part of the 1955–58 Commonwealth Trans-Antarctic Expedition – completing the first overland Antarctic crossing via the south pole. This shot was taken during the 1964-1965 summer campaign, as they were surveying the displacement of glaciers in the Sør Rondane Mountains, East Antarctica.  At that time, the men had to leave the base station for three weeks with two dog-sled pulled by a small skidoo-like vehicle. Remarkably, this shot doesn’t look too dissimilar to many field campaigns today, where the same type of sledges are still used and the clothing worn is also very similar. However, logistical support was very different, with no technicians or field guides those who were part of the polar expeditions of 50 years ago had to be experts at everything!

The second picture illustrates how precise positions (and relative displacements) were measured at that time. No fancy GPS technology, but a network of markers and theodolites. The shot was taken on a pinning point, close to the front of the Roi Baudouin Ice shelf, during the overwintering campaign of 1965 (where people had to stay in Antarctica for 15 months).

A geodesist measuring the precision position of a marker with his theodolite, overwintering campaign in Antarctica, 1965. (Credit: Jean-Jacques Derwael)

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Image of the Week – Changes in the Greenland Ice Sheet Documented by Satellite

Image of the Week – Changes in the Greenland Ice Sheet Documented by Satellite

Monitoring the changing ice mass of the Greenland Ice Sheet provides valuable information about how the ice sheet is responding to changing climate, but how do we make these measurements over such a large area of ice? Using NASA’s GRACE satellites (twin-satellites flying in formation) it is possible to make detailed measurements of the Earth’s gravitational field. As ice is gained/lost from the ice sheet the local gravitational field will change. This will cause the distance between the two GRACE satellites to change by a small amount as they pass over the ice sheet and by measuring the changing distance between the two satellites with very high precision, the change in ice mass can be determined.

The image above shows the change in mass of the Greenland Ice Sheet between January 2004 and June 2014 (updated from Luthcke et al., 2013). The colours indicate the change in mass in units of water height equivalent ranging from -250 to +250 centimetres, with blue indicating a mass gain and red areas a mass loss. The graph overlay shows the total accumulated change in gigatons over the ten year period.  A video animation of the changes over time can be seen using the NASA scientific visualisation studio:

Converting changes in the measured gravitational field to ice mass is a complex process and other factors contributing towards the change in gravitational field must be accounted for. One major factor is glacial isostatic adjustment (Earth’s mass redistribution in response to historical ice loading). To learn more about how glacial isostatic adjustment is accounted for to extract the ice mass change signal see Peltier et al. 2015.

Image of the Week — Happy ValentICE’s day

Image of the Week — Happy ValentICE’s day

On the eve of 14 February, love and little hearts are everywhere, even trapped in lake ice!
The EGU Cryosphere blog team wishes you a happy Valentine’s Day 🙂

Behind this nice picture, there is also science

This picture was taken during a laboratory experiment that aimed to reproduce the bubbles observed in Arctic lake ice in the winter.

In this shot, we can see two types of gas bubbles in the ice. The elongated vertical bubbles are formed after the exsolution of gas at the water-ice interface. The gas present in “heart-shaped” bubbles originates from ebullition (i.e. it has been emitted as bubbles from the sediment) and it contains a large amount of methane, a significant greenhouse gas. In both cases, the gas is trapped in the ice during the downward evolution* of the freezing front but the shape and gas content of the bubbles largely depends on the velocity of the freezing front development.

The goal of this research is to better understand the origin of the methane emitted by Artic lakes and unravel the role of lake ice cover on the methane atmospheric burden.

*During the winter, the cold atmosphere cools down the water of the lake, when the freezing point is reached, a thin layer of layer of lake ice starts to form at the surface and extends downward.

Further reading/Reference

Boereboom, T., Depoorter, M., Coppens, S., and Tison, J.-L.: Gas properties of winter lake ice in Northern Sweden: implication for carbon gas release, Biogeosciences, 9, 827-838, doi:10.5194/bg-9-827-2012, 2012.

Sapart, C. J et al (in preparation).

Image of the Week — slush on top of sea ice

Image of the Week — slush on top of sea ice

Many glaciologists look forward to going on fieldtrips and then, once they are back, they make us dream by posting breathtaking photos (like THIS or THIS or THIS). However, the reality of the field can sometimes be very different….

The picture illustrates how difficult it can be to work on sea ice when the snow on top of it starts to melt and forms slush (a mixture of snow and liquid water that looks very much like an Italian granita).

Here, the sled carrying the field equipment is half drowned in the slush while the technician who came to the rescue (with his skidoo in the back) is also sunk.

On this blog post you can read about another expedition of M. Kotovitch on sea ice.

Edited by Emma Smith

 

Image of the Week: Icequakes! Stick-Slip motion under Western Greenland

Image of the Week: Icequakes! Stick-Slip motion under Western Greenland
The Greenland Ice Sheet contains enough fresh water to raise global sea level by around 6 m, therefore it is very important to understand how the ice moves from the interior of the ice sheet towards the oceans. Processes that happen at the base of the ice sheet, where the ice meets the bed, are known to be a key control on how the ice moves. Geophysical techniques, such as recording tiny icequakes that happen as the ice moves over it’s bed, can be used to investigate the basal dynamics that accommodate this movement.

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