GeoLog

Cryospheric Sciences

Imaggeo on Mondays: Nor’Wester in the Southern Alps of New Zealand

Imaggeo on Mondays: Nor’Wester in the Southern Alps of New Zealand

Stephan Winkler’s 2017 Imaggeo Photo Contest finalist photo showcases an unusual weather phenomenon…

The image shows a typical weather situation in the Southern Alps of New Zealand with a moist, westerly airflow pushing over the Main Divide [which separates the water catchments of the more heavily populated eastern side of the island from those on the west coast] to create a typical foehn wind [dry and warm winds which form on the downside of a mountain range] pattern (locally called Nor’Wester) in the region. Immediately west of this Main Divide, annual precipitation of up to 15,000 mm has been estimated.

The upper part of Tasman Glacier, as other glaciers around and immediately east of the Main Divide, receive impressive amounts of snow due to an overspill effect and can still be regarded as maritime.

In the image, however, the situation is displayed when right at the Main Divide the clouds disappear due to increasing temperatures when flowing over the Divide. The foehn wind developing with such weather pattern can be very strong. However, the image nicely shows how the glaciation of the central Southern Alps is influence by the availability of moisture and the dynamic character of the regional climate.

Description by Stephan Winkler (Senior Lecturer in Quaternary Geology and Palaeoclimatology at the University of Canterbury), as published previously on imaggeo.egu.eu

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

 

Imaggeo on Mondays: Sediments make the colour

Imaggeo on Mondays: Sediments make the colour

Earth is spectacularly beautiful, especially when seen from a bird’s eye view. This image, of a sweeping pattern made by a river in Iceland is testimony to it.

The picture shows river Leirá which drains sediment-loaded glacial water from the Myrdalsjökull glacier in Iceland. Myrdalsjökull glacier covers Katla, one of Iceland’s most active and ice-covered volcanoes.

A high sediment load (the suspended particles which are transported in river water) is typical for these glacial rivers and is visible as the fast-flowing glacial river (on the right of this image) appears light brown in colour. The sediment is gradually lost in the labyrinth of small lakes and narrow, crooked connections between lakes as can be seen as a gradual change in colour to dark blue.

The sediment load, height of the water  and chemistry of this and other glacial rivers are measured partly in real-time by the Icelandic Meteorological Office. This is done for research purposes and in order to detect floods from subglacial lakes that travel up to several tens of kilometers beneath the glacier before they reach a glacial river.

These glacial outburst floods do not only threaten people, livestock and property, but also infrastructure such as Route 1, a circular, national road which runs around the island. They occur regularly due to volcanic activity or localized geothermal melting on the volcano, creating a need for an effective early-warning system.

Advances in the last years include the usage of GPS instruments on top of a subglacial lake and the flood path in order to increase the early-warning for these floods. In 2015, the GPS network, gave scientists on duty at the Icelandic Meteorological Office 3.5 days of warning before one of the largest floods from western Vatnajökull emerged from beneath the ice.

The peak discharge exceeded 2000 m3/s,  which is comparable to an increase in discharge from that of the Thames to that of the Rhine.  This flood was also pioneeringly monitored with clusters of seismometers, so called arrays (from University College Dublin & Dublin Institute for Advanced Studies, Ireland), that enabled an early-warning of at least 20 hours and allowed to track the flood front merely using the ground vibrations it excited. The flood propagated under the glacier at a speed of around 2 km/h; so assuming you can keep up the speed over nearly a day you can escape the flood by walking while it is moving beneath the glacier.

Related publications about the tracking of these subglacial floods will emerge in the published literature soon (real time update available at www.evapseibl.wordpress.com).

By Eva Eibl, researcher at the Dublin Institute for Advanced Studies.

Thanks go to www.volcanoheli.is who organised this trip.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

 

Imaggeo on Mondays: Tongue of a small giant

Imaggeo on Mondays: Tongue of a small giant

In a world where climate change causes many mountain glaciers to shrink away, bucking the ‘melting’ trend is not easy. In today’s post, Antonello Provenzale, a researcher in Italy, tells us of one glacier in the Alps which is doing just that.

Mountain glaciers are retreating worldwide, with the possible exception of the Karakoram area. For most glaciers, ablation (ice melt) during the warm season is stronger than the accumulation of new ice by snowfall. As a result, while glacier ice flows downhill, the accelerated melting at lower elevation forces the terminus of the glacier to retreat uphill, with a net loss of ice volume.

Such behavior is especially evident on the southern flank of the Alps, where many mountain glaciers have dramatically reduced their dimensions, often fragmenting into smaller, detached pieces.

An important exception is represented by the Miage glacier in Val Veny, Val d’Aosta, northwestern Italy, at the base of the Mount Blanc massif. This glacier is covered with a thick layer of debris, which protects the underlying ice from the direct heating by sunlight. The rocks which make up the debris are poor heat conductors and thus preserve the ice beneath them, making this glacier particularly stable.

This glacier is so stationary that vegetation and trees have grown on its margins and on the debris. Several ponds punctuate the surface of the glacier, as well as some areas on its sides. The Miage lake, for example, is directly in contact with the slowly flowing ice and it is sometimes run by large outburst waves generated by huge blocks of ice and rock falling into the lake water.

This picture was taken in September 2014, during a field excursion of the Italian Glaciological Committee. The image is a composition (stitch) of several images taken with a moderate wide angle lens on a rangefinder digital camera.

By Antonello Provenzale studies Geophysical Fluid Dynamics, Earth System processes and Geosphere-Biosphere interactions at the Institute of Geosciences and Earth Resources of the National Research Council of Italy.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

June GeoRoundUp: the best of the Earth sciences from around the web

June GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, as well as unique and quirky research news, this monthly column aims to bring you the best of the Earth and planetary sciences from around the web.

Major Story

With June being the month when the world’s oceans are celebrated with World Ocean Day (8th June) and the month when the UN’s Ocean Conference took place, it seemed apt to dedicate our major story to this precious, diverse and remote landscape.

In fact, so remote and inaccessible are vast swathes of our oceans, that 95% of them are unseen (or unvisited) by human eyes. Despite their inaccessibility, humans are hugely reliant on the oceans.  According to The World Bank, the livelihoods of approximately 10 to 12% of the global population depends on healthy oceans and more than 90%of those employed by capture fisheries are working in small-scale operations in developing countries. Not only that, but the oceans trap vast amounts of heat from the atmosphere, limiting global temperature rise.

Yet we take this valuable and beautiful resource for granted.

As greenhouse gas emissions rise, the oceans must absorb more and more heat. The ocean is warmer today than it has been since recordkeeping began in 1880. Over the past two decades this has resulted in a significant change in the composition of the upper layer of water in our oceans. Research published this month confirms that ocean temperatures are rising at an alarming rate, with dire consequences.

Corals are highly sensitive to changes in ocean temperatures. The 2015 to 2016 El Niño was particularly powerful. As its effects faded, ocean temperatures in the Pacific, Atlantic and Indian oceans remained high, meaning 70 percent of corals were exposed to conditions that can cause bleaching. Almost all of the 29 coral reefs on the U.N. World Heritage list have now been damaged by bleaching.

This month, the National Oceanic and Atmospheric Administration (NOAA) declared that bleaching was subsiding for the first time in three years. Some of the affected corals are expected to take 10 to 15 years to recover, in stress-free conditions. But as global and ocean temperatures continue to rise, corals are being pushed closer to their limits.

Warmer ocean temperatures are also causing fish to travel to cooler waters, affecting the livelihoods of fishermen who depend on their daily catch to keep families afloat and changing marine ecosystems forever. And early this month, millions of sea-pickles – a mysterious warm water loving sea creature- washed up along the western coast of the U.S, from Oregon to Alaska. Though scientists aren’t quite sure what caused the bloom, speculation is focused on warming water temperatures.

It is not only warming waters which are threatening the world’s oceans. Our thirst for convenience means a million plastic bottles are bought around the world every minute. Campaigners believe that the environmental crisis brought about by the demand for disposable plastic products will soon rival climate change.

In 2015 researchers estimated that 5-13 million tonnes of plastics flow into the world’s oceans annually, much coming from developing Asian nations where waste management practices are poor and the culture for recycling is limited. To tackle the problem, China, Thailand, Indonesia and the Philippines vouched to try and keep more plastics out of ocean waters. And, with a plastic bottle taking up to 450 years to break down completely, what happens to it if you drop it in the ocean? Some of it, will likely find it’s way to the Arctic. Indeed, recent research suggests that there are roughly 300 billion pieces of floating plastic in the polar ocean alone.

A bottle dropped in the water off the coast of China is likely be carried eastward by the north Pacific gyre and end up a few hundred miles off the coast of the US. Photograph: Graphic. Credit: If you drop plastic in the ocean, where does it end up? The Guardian. Original Source: Plastic Adrift by oceanographer Erik van Sebille. Click to run.

And it’s not only the ocean waters that are feeling the heat. As the demand for resources increases, the need to find them does too. The sea floor is a treasure trove of mineral and geological resources, but deep-sea mining is not without environmental concerns. Despite the ethical unease, nations are rushing to buy up swathes of the ocean floor to ensure their right to mine them in the future. But to realise these deep-water mining dreams, advanced technological solutions are needed, such as the remote-controlled robots Nautilus Minerals will use to exploit the Bismarck Sea, off the coast of Papua New Guinea.

What you might have missed

Lightning reportedly ignited a deadly wildfire in Portugal, seen here by ESA’s Proba-V satellite on 18 June.

“On June 17, 2017, lightning reportedly ignited a deadly wildfire that spread across the mountainous areas of Pedrógão Grande—a municipality in central Portugal located about 160 kilometers (100 miles) northeast of Lisbon”, reported NASA – National Aeronautics and Space Administration. The death toll stands at 62 people (as reported by BBC News). The fires were seen from space by satellites of both NASA and ESA – European Space Agency satellites.

Large wildfires are also becoming increasing common and severe in boreal forests around the world. Natural-color images captured by NASA satellites on June 23rd, shows wildfires raging near Lake Baikal and the Angara River in Siberia. At the same time, a new study has found a link between lightning storms and boreal wildfires, with lightning strikes thought to be behind massive fire years in Alaska and northern Canada. This infographic further explores the link between wildfires triggered both by lightning and human activities.

Meanwhile, in the world’s southernmost continent the crack on the Larsen C ice-shelf continues its inexorable journey across the ice. The rift is set to create on of the largest iceberg ever recorded. Now plunged in the darkness of the Antarctic winter, obtaining images of the crack’s progress is becoming a little tricker. NASA used the Thermal Infrared Sensor (TIRS) on Landsat 8 to capture a false-color image of the crack. The new data, which shows an acceleration of the speed at which the crack is advancing, has lead scientists to believe that calving of the iceberg to the Weddell Sea is imminent.

Links we liked

The EGU story

This month saw the launch of two new division blogs over on the EGU Blogs: The Solar-Terrestrial Sciences and the Geodynamics Division Blogs. The EGU scientific divisions blogs share division-specific news, events, and activities, as well as updates on the latest research in their field.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

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