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Imaggeo on Mondays: Tasman Lake Down Under 

Imaggeo on Mondays: Tasman Lake Down Under 

The Tasman Glacier Terminal Lake, seen in this photograph, lies in the Aoraki Mount Cook National Park in New Zealand’s south island. The photographer, Martina Ulvrova, stated she “finally got to see the largest glacier in New Zealand after several days of heavy rain, during which the landscape was bathing in mist”.

The Tasman Glacier is 23 km long and is surrounded by a terminal proglacial lake with floating icebergs. The lake was only formed in the 1970s by the melting of the Tasman Glacier. Today the lake is 7 km long and growing faster than ever with its length that is increasing by approximately 180 m per year on average!

This continual lake growth is largely due to the receding glacier which has been retreating since the 1970s and has shrunk by approximately 6 km over the past fifty years. Blocks of ice regularly break-off the flowing glacier and float peacefully on the lake. One can see only the tips of these enormous icebergs with about 90% of the iceberg mass hidden below the surface of the water.

In 2011, after a 6.3 magnitude earthquake, 40 million tonne chunk of ice broke away from the Tasman glacier and plunged into the lake. The collapse of the gigantic block caused a local tsunami with waves as high as three meters bouncing from side to side across the lake for thirty minutes. Scientists expect the Tasman glacier to continue shrinking considerably and warn that it is likely to eventually disappear. Global warming has hit this secret paradise and predictions are alarming.

By Martina Ulvrova

If you pre-register for the 2018 General Assembly (Vienna, 08–13 April), you can take part in our annual photo competition! From 15 January until 15 February, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submittheir 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/.

EGU Photo Contest 2018: Now open for submissions!

EGU Photo Contest 2018: Now open for submissions!

If you are pre-registered for the 2018 General Assembly (Vienna, 8 – 13 April), you can take part in our annual photo competition! Winners receive a free registration to next year’s General Assembly!

The ninth annual EGU photo competition opens on 15 January. Up until 15 February, every participant pre-registered for the General Assembly can submit up three original photos and one moving image on any broad theme related to the Earth, planetary, and space sciences.

Shortlisted photos will be exhibited at the conference, together with the winning moving image, which will be selected by a panel of judges. General Assembly participants can vote for their favourite photos and the winning images will be announced on the last day of the meeting.

If you submit your images to the photo competition, they will also be included in the EGU’s open access photo database, Imaggeo. You retain full rights of use for any photos submitted to the database as they are licensed and distributed by EGU under a Creative Commons license.

You will need to register on Imaggeo so that the organisers can appropriately process your photos. For more information, please check the EGU Photo Contest page on Imaggeo.

Previous winning photographs can be seen on the 20102011, 2012,  2013, 2014, 2015, 2016 and 2017 winners’ pages.

In the meantime, get shooting!

EGU 2018 will take place from 08 to 13 April 2017 in Vienna, Austria. For more information on the General Assembly, see the EGU 2018 website and follow us on Twitter (#EGU18 is the official conference hashtag) and Facebook.

 

Announcing the winners of the EGU Photo Contest 2017!

The selection committee received over 300 photos for this year’s EGU Photo Contest, covering fields across the geosciences. Participants at the 2017 General Assembly have been voting for their favourites throughout the week  of the conference and there are three clear winners. Congratulations to 2017’s fantastic photographers!

Penitentes in the Andes by Christoph Schmidt (distributed by imaggeo.egu.eu). This photo was taken in the Bolivian Andes at an altitude of around 4400 m. The climatic conditions favour the formation of so-called penitents, i.e. long and pointed remains of a formerly comprehensive snow field.

Symbiosis of fire, ice and water by Michael Grund (distributed by imaggeo.egu.eu). This picture was taken at Storforsen, an impressive rapid in the Pite River in northern Sweden.

Movement of the ancient sand by Elizaveta Kovaleva (distributed by imaggeo.egu.eu). In the Zion National Park you can literally touch and see the dynamic of the ancient sand dunes.

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/.

Geosciences column: Making aurora photos taken by ISS astronauts useful for research

Geosciences column: Making aurora photos taken by ISS astronauts useful for research

It’s a clear night, much like any other, except that billions of kilometers away the Sun has gone into overdrive and (hours earlier) hurled a mass of charged particles, including protons, electrons and atoms towards the Earth.  As the electrons slam into the upper reaches of the atmosphere, the night sky explodes into a spectacular display of dancing lights: aurora.

Aurora remain shrouded in mystery, even to the scientists who’ve dedicate their lives to studying them. Photographs provide an invaluable source of data which can help understand the science behind them. But, for aurora images to be of scientific value researchers need to know when they were taken and, more importantly, where.

You’ve got to be in the right place at the right time to catch a glimpse of the elusive phenomenon. In the Northern Hemisphere, aurora season peaks in autumn through to winter. Geographically, the best chance of seeing them is at latitudes between 65 and 72 degrees – think the Nordic countries.

That is unless you are an astronaut on the International Space Station (ISS), in which case, you’ve got the best seat in the house!

The orbit of the ISS means it skims past the point at which aurora intensity is at its peak, which also happens to be the point at which they look their most spectacular. Its orbital speed means it can get an almost global-scale snapshot of an aurora, passing over the dancing lights in just under 5 minutes.

Not as much is known about Aurora Australis (those which occur in the southern hemisphere) as we do about the Northern Lights (visible in the northern hemisphere), because there are far less ground-based auroral imagers south of the equator. The ISS orbit means that astronauts photograph Aurora Australis almost as frequently as Aurora Borealis, helping to fill the gap.

Testament to the privileged viewpoint is the hoard of photographs ISS astronauts have amassed over time – perfect for scientists who study aurora to use in their research.

Time-lapse shot from the International Space Station, showing both the Aurora Borealis and Aurora Australis phenomena. Credit: NASA

Except that, until recently, the ISS photographs were of little scientific value because they aren’t georeferenced. The images are captured by astronauts in their spare time using commercial digital single lenses reflector cameras (DSLRs), which can’t pinpoint the location at which the photographs were taken – they were never intended to be used in research.

Now, researchers at the European Space Agency (ESA) have developed a method which overcomes the problem. By mapping the stars captured in each of the photographs and the timestamp on the image (as determined by the camera used to take the photograph), the team are now able to geolocated the images, giving them accurate orientation, scale and timestamp information.

Despite the success, it’s not a straightforward thing to do. One of the main problems is that the timestamps aren’t always accurate. Internal clocks in DSLRs have a tendency to drift. Over the period of a week they can be out by as much as a minute, making it difficult to establish the location of the ISS when the image was captured. This has implications when creating the star map, as the location of the station is used as a starting point.

To resolve the issue, aurora images which also include city lights can be aligned to geographical maps using reference city markers to get a timestamps accurate to within one second or less. In the absence of city lights, images which also capture the Earth’s horizon are aligned with its expected position instead. The correction works best if both city lights and the horizon can be used.

Errors are also introduced when the star maps can’t be fully resolved (due to the original image being noisy, for example) and because the method assumes that auroras originate from a single height, which isn’t true either.

detailed comparison between the ISS image plotted in Fig. 11 (b) and the contemporaneous image acquired by the SNKQ THEMIS ASI (a) . The original ISS image is plotted in (c) . Red and blue symbols trace the locations of the j shaped arc and northern edge of the main auroral arc, respectively, derived from their locations in the THEMIS image. The features are marked with the same coloured arrows in (c) . The magenta arrows point out a vertical feature projected very differently in (a) and (b) .

A detailed comparison between an ISS image of aurora (a) plotted and (b) the contemporaneous image acquired by the SNK THEMIS ASI [ground-based]. The original ISS image (a) is plotted in (c). For more detail see Riechert, et al., 2016.

Comparing images of an aurora on 4 February 2012, captured both by the ISS crew and a ground-based instrument, has allowed the researchers to test the accuracy of their method. Overall, the results show good agreement, but highlight that the projection of the ISS images has to be taken into account when interpreting the results.

Now, a trove of thousands of Aurora Borealis and Australis photographs can be used by researchers to decipher the secrets of one the planet Earth’s most awe-inspiring phenomenon.

By Laura Roberts Artal, EGU Communications Officer

 

References:

Riechert, M., Walsh, A. P., Gerst, A., and Taylor, M. G. G. T.: Automatic georeferencing of astronaut auroral photography, Geosci. Instrum. Method. Data Syst., 5, 289-304, doi:10.5194/gi-5-289-2016, 2016.

Automatic georeferencing of astronaut auroral photography: http://www.cosmos.esa.int/web/arrrgh

The research was accomplished using only free and open-source software. All the images processed to date are made freely available at htttp://cosmos.esa.int/arrgh, as is the software needed to produce them.