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 Greenland Maps Show More Glaciers ou l'évolution des temps.

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yanis la chouette

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Date d'inscription : 12/11/2005

MessageSujet: Greenland Maps Show More Glaciers ou l'évolution des temps.   Jeu 2 Nov à 9:20

News | November 1, 2017
New Greenland Maps Show More Glaciers at Risk.

New maps of Greenland's coastal seafloor and bedrock beneath its massive ice sheet show that two to four times as many coastal glaciers are at risk of accelerated melting as previously thought.

Researchers at the University of California at Irvine (UCI), NASA and 30 other institutions have published the most comprehensive, accurate and high-resolution relief maps ever made of Greenland's bedrock and coastal seafloor. Among the many data sources incorporated into the new maps are data from NASA's Ocean Melting Greenland (OMG) campaign.

Lead author Mathieu Morlighem of UCI had demonstrated in an earlier paper that data from OMG's survey of the shape and depth, or bathymetry, of the seafloor in Greenland's fjords improved scientists' understanding not only of the coastline, but of the inland bedrock beneath glaciers that flow into the ocean. That's because the bathymetry where a glacier meets the ocean limits the possibilities for the shape of bedrock farther upstream.

Above image shows a stretch of Greenland's coastline as created by BedMachine before and after the inclusion of new OMG data. Credit: UCI

The nearer to the shoreline, the more valuable the bathymetry data are for understanding on-shore topography, Morlighem said. "What made OMG unique compared to other campaigns is that they got right into the fjords, as close as possible to the glacier fronts. That's a big help for bedrock mapping." Additionally, the OMG campaign surveyed large sections of the Greenland coast for the first time ever. In fjords for which there are no data, it's difficult to estimate how deep the glaciers extend below sea level.

The OMG data are only one of many datasets Morlighem and his team used in the ice sheet mapper, which is named BedMachine. Another comprehensive source is NASA's Operation IceBridge airborne surveys. IceBridge measures the ice sheet thickness directly along a plane's flight path. This creates a set of long, narrow strips of data rather than a complete map of the ice sheet. Besides NASA, nearly 40 other international collaborators also contributed various types of survey data on different parts of Greenland.

No survey, not even OMG, covers every glacier on Greenland's long, convoluted coastline. To infer the bed topography in sparsely studied areas, BedMachine averages between existing data points using physical principles such as the conservation of mass.

The new maps reveal that two to four times more oceanfront glaciers extend deeper than 600 feet (200 meters) below sea level than earlier maps showed. That's bad news, because the top 600 feet of water around Greenland comes from the Arctic and is relatively cold. The water below it comes from farther south and is 6 to 8 degrees Fahrenheit (3 to 4 degrees Celsius) warmer than the water above. Deeper-seated glaciers are exposed to this warmer water, which melts them more rapidly.

Morlighem's team used the maps to refine their estimate of Greenland's total volume of ice and its potential to add to global sea level rise, if the ice were to melt completely -- which is not expected to occur within the next few hundred years. The new estimate is higher by 2.76 inches (7 centimeters) for a total of 24.34 feet (7.42 meters).

OMG Principal Investigator Josh Willis of JPL, who was not involved in producing the maps, said, "These results suggest that Greenland's ice is more threatened by changing climate than we had anticipated."

On Oct. 23, the five-year OMG campaign completed its second annual set of airborne surveys to measure, for the first time, the amount that warm water around the island is contributing to the loss of the Greenland ice sheet. Besides the one-time bathymetry survey, OMG is collecting annual measurements of the changing height of the ice sheet and the ocean temperature and salinity in more than 200 fjord locations. Morlighem looks forward to improving BedMachine's maps with data from the airborne surveys.

The maps and related research are in a paper titled "BedMachine v3: Complete bed topography and ocean bathymetry mapping of Greenland from multi-beam echo sounding combined with mass conservation" in Geophysical Research Letters.

News Media Contact
Alan Buis
Jet Propulsion Laboratory, Pasadena, California

Brian Bell
University of California, Irvine

Written by Carol Rasmussen
NASA's Earth Science News Team



Title Ghostly green
Released 02/11/2017 8:45 am
Copyright ESA/D. O'Donnell

Just in time for Halloween this week: a green deep-space tracking station.

This image was taken by Byron Bay-based astrophotographer Dylan O'Donnell in October during a photo shoot at the New Norcia station, some 120 km north of Perth, Western Australia.

The ‘ghostly green’ was created by reflecting a floodlight off the station’s 35 m-diameter deep-space antenna and structure.

The station routinely communicates with spacecraft orbiting Mars as well as ESA’s Gaia and XMM observatory missions. In future, it will link up with BepiColombo at Mercury and the Euclid astronomical observatory.

Since August, the station has been operating in part on a new solar power system, which, together with a local water recycling system, is helping to boost the station’s sustainability and reduce its environmental impact.

More information

Estrack network

New Norcia station
Id 385873


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yanis la chouette

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MessageSujet: Re: Greenland Maps Show More Glaciers ou l'évolution des temps.   Ven 3 Nov à 10:12

Title Western Australia
Released 03/11/2017 10:00 am
Copyright contains modified Copernicus Sentinel data (2017), processed by ESA, CC BY-SA 3.0 IGO
From the fourth most populous city to the rugged Outback, the Sentinel-3A satellite gives us a wide-ranging view over Australia’s southwestern corner.

This perspective from space clearly illustrates human’s influence on our environment: the agricultural landscape that dominates in the lower-left is suddenly interrupted by the more densely vegetated national parks and forests.

The city of Perth is located on the coast along the left edge of the image. About 150 km north of Perth sits ESA’s tracking station at New Norcia, where a 35 m-diameter radio dish communicates with deep-space missions such as Rosetta and Mars Express.

Moving further inland, grasslands give way to the deserts of Australia’s vast and remote interior – known as the Outback – with a landscape dominated by red soil and sparse vegetation. Several large salt lakes are visible across the image in white, including the appropriately named Lake Disappointment by explorer Frank Hann in search of fresh water (top of image).

Clouds over the ocean obstruct our view of the southern coast, but the lack of cloud cover over the interior desert pronounces the dry climate, which is a consequence of global wind patterns.

Sentinel-3 offers a ‘bigger picture’ for Europe’s Copernicus programme by systematically monitoring Earth’s oceans, land, ice and atmosphere to understand large-scale global dynamics.

While the satellite mission carries a suite of cutting-edge instruments, this image, also featured on the Earth from Space video programme, was captured on 9 April 2017 by the satellite’s Ocean and Land Colour Instrument, which helps to monitor ocean ecosystems, supports crop management and agriculture, and provides estimates of atmospheric aerosol and clouds.

Id 385920

Camille Saint-Saëns - Danse Macabre

Tartini Violin Sonata in G minor ''Devil's Trill Sonata''

3 November 2017
When is the last time you used space technology? Probably a matter of minutes ago, if you took bearings on your phone, checked the weather or withdrew money. Starting today, European Space Week celebrates space for the rest of us – as a source of services, jobs and business opportunities.

Hosted in Talinn, Estonia, 3–9 November, European Space Week is bringing together space stakeholders, companies and visionaries, including ESA Director General Jan Woerner.

The Space Week includes a hackathon, conferences, an information day on space-themed elements of the EU’s Horizon 2020 research and development programme, a space exhibition and the opening of ESA’s latest business incubator.

Prof. Woerner joins high-level speakers such as Elżbieta Bieńkowska, European Commissioner for Internal Market, Industry, Entrepreneurship and Small- and Medium-sized Enterprises; Urve Palo, Minister of Entrepreneurship and Information Technology of Estonia; and Carlo des Dorides, Executive Director of the European Global Navigation Satellite System Agency.

A focus is to forge links between the space and digital communities, as well as highlighting the torrents of data now freely available from Europe’s Copernicus Earth-monitoring programme and its Galileo positioning system.

A three-day Integrated Applications Hackathon begins today, challenging developers to combine Copernicus Earth-observing satellite data with Galileo satnav data plus social media to design innovative, integrated services.

The team behind ESTCube-1, Estonia’s first space mission – a CubeSat launched in 2013 – will offer support on integrating space hardware into service concepts.

Estonian incubator
Urve Palo, Estonia Minister of Entrepreneurship and Information Technology, highlighted her nation’s hosting of the event: “Cooperation between the ICT industry, start-ups and European space industry is making space data more accessible.

“Digital Europe and the free movement of data are priorities for our Presidency of the Council of the EU, and also the focus of Space Week.”

The Minister stressed that Europe’s space policy has a broader objective of boosting employment, investment, growth and, ultimately, the global competitiveness of the EU.

Satellite mapping Estonia's forests
“In line with the digital agenda of the Estonian Presidency, we emphasise, among other things, the smarter application of digital technologies in the space sector,” she added, stressing the need to increase access to space data for innovative businesses.

“It gives entrepreneurs the opportunity to develop new products and services, taking advantage of the opportunities offered by the EU’s space programmes and the availability of space-based data for both Earth observation and satellite navigation.”

Just in time for Halloween ?

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MessageSujet: Re: Greenland Maps Show More Glaciers ou l'évolution des temps.   Ven 3 Nov à 10:12

Because Jupiter is so big, it has been influential in the story of the solar system. We can’t understand the origin of the solar system – and how Earth came about – without understanding how Jupiter formed. There’s still a lot we don’t know about Jupiter: what is it made of? What lies beneath those beautiful, swirling clouds? What exactly drives its magnetic field?

We think that giant planets like Jupiter are the cornerstones of planet formation. These planets were assembled early in the process, before their young stars had the chance to absorb or blow away the light gases in the huge cloud from which they were born. Giant planets also play a big role in planet formation because their huge masses allow them to shape the orbits of other objects in their planetary systems, such as other planets, asteroids, and comets.
Although we have pieced together the basic story of Jupiter’s origin, some important questions remain, and Juno’s mission is to help us answer them. Exactly how early was Jupiter born? Jupiter might have formed at its current orbit, but some evidence also suggests that it could have formed farther from the sun before migrating inward. Because Jupiter formed at the same time as the sun, their chemical compositions should be similar. But Jupiter has more heavy elements – such as carbon and nitrogen – than the Sun.
Competing formation theories make different predictions about the content and mass of Jupiter’s core, so measuring the core will allow us to eliminate ideas that are wrong. Determining the amount of water – and therefore oxygen – in the gas giant is important not only for understanding how the planet formed, but also how heavy elements were transferred across the solar system. These heavy elements were crucial for the existence of rocky planets like Earth – and life. Since Jupiter is the best example of a gas giant that we have, learning its history will help us understand the hundreds of giant planets we’ve discovered orbiting other stars.

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