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TOPIC: The Earth


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Earth's Water
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A NASA Space Sleuth Hunts the Trail of Earth's Water
For the first time, NASA scientists have used a shrewd spaceborne detective to track the origin and movement of water vapour throughout Earth's atmosphere. This perspective is vital to improve the understanding of Earth's water cycle and its role in weather and climate.
NASA's newest detective in the mysteries of atmospheric water vapour is the Tropospheric Emission Spectrometer instrument on the Aura satellite. A team of scientists from NASA's Jet Propulsion Laboratory, Pasadena, California, and the University of Colorado, Boulder, used the instrument's observations of heavy and light water vapour to retrace the "history" of water over oceans and continents, from ice and liquid to vapour and back again. Heavy water vapour molecules have more neutrons than lighter ones do.
By analysing the distribution of the heavy and light molecules, the team was able to deduce the sources and processes that cycle water vapour, the most abundant greenhouse gas in Earth's atmosphere.
The team found that tropical rainfall evaporation and water "exhaled" by forests are key sources of moisture in the tropical atmosphere. They noted that more water than they had expected is transported over land rather than ocean into the lower troposphere (Earth's lowermost atmosphere), especially over the Amazon River basin and tropical Africa.

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RE: The Earth
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Title: Evidence of high water content in the deep upper mantle inferred from deformation microstructures
Authors: Ikuo Katayama, Shun-ichiro Karato, Mark Brandon
Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA

Deep upper-mantle rocks from the Norwegian Caledonides show evidence for large strain deformation in both olivine and garnet under varying water contents. Using microstructural observations, including lattice-preferred orientation of olivine and subgrain boundaries of majoritic garnet, we infer the following deformation history. At depths exceeding ~150 km, large strain deformation occurred at low stress (~10 MPa) and modest temperature (~1300 K), involving high water content (>1000 H/106Si in olivine). This was followed by low strain deformation at lower water content (~200–1000 H/106Si) and modest stress (~40 MPa) in the shallower parts. These observations show that the deep upper mantle in this region had a considerably higher water content than the upper mantle near mid-ocean ridges.

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On August 13, 2005, the remote Ayles Ice Shelf on Ellesmere Island in northern Canada broke free and began drifting out to sea.

ayles
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Credit NASA

83°1.5′N 77°33.5′W

-- Edited by Blobrana at 01:35, 2007-01-06

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L

Posts: 131433
Date:
The Ayles Ice Shelf
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88.16955W_78.00222N
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L

Posts: 131433
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RE: The Earth
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A giant ice shelf the size of 11,000 football fields has snapped free from Canada's Arctic, scientists said. The mass of ice broke clear 16 months ago from the coast of Ellesmere Island, about 497 miles south of the North Pole, but no one was present to see it in Canada's remote north. Scientists using satellite images later noticed that it became a newly formed ice island in just an hour and left a trail of icy boulders floating in its wake.
Warwick Vincent of Laval University, who studies Arctic conditions, travelled to the newly formed ice island and could not believe what he saw.

"This is a dramatic and disturbing event. It shows that we are loosing remarkable features of the Canadian North that have been in place for many thousands of years. We are crossing climate thresholds, and these may signal the onset of accelerated change ahead" - Warwick Vincent.

In 10 years of working in the region he has never seen such a dramatic loss of sea ice.
The collapse was so powerful that earthquake monitors 155 miles away picked up tremors from it.
The Ayles Ice Shelf, roughly 41 square miles in area, was one of six major ice shelves remaining in Canada's Arctic.
Scientists say it is the largest event of its kind in Canada in 30 years and point their fingers at climate change as a major contributing factor.

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Posts: 131433
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GOCE: getting the low down on gravity
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By measuring the Earth's gravity field and modelling the geoid, or hypothetical surface of the Earth, with extremely high accuracy and spatial resolution, GOCE will significantly advance our knowledge of how the Earth works in several domains – oceanography, geophysics and geodesy – as well as providing insight into the physics and dynamics of the Earth's interior, such as volcanism and earthquakes.

Podcast (26mb, MP4)

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RE: The Earth
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Over 50 doctoral level Chinese scientists from 30 institutes have gathered at the prestigious Peking University in Beijing in the People’s Republic of China to attend a six-day advanced training course devoted to atmosphere monitoring over China using ESA remote sensing instruments.

atmoshperecloud
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Credit ESA

ESA and the National Remote Sensing Centre of China (NRSCC) are sponsoring the course under the framework of the Dragon Programme – a wide-ranging research initiative designed to encourage increased exploitation of ESA remote sensing satellite data within China as well as stimulate increased scientific co-operation in the field of Earth Observation (EO) science and applications between China and Europe.

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Evolution of the continental crust
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The Earth’s continental crust differs from the crust of other planets in our Solar System. It supports life, its formation modified the composition of the mantle and the atmosphere, and it remains a sink for CO2 through weathering and erosion. The continental crust has therefore had a key role in the evolution of this planet, and yet when and how it formed remain the topic of considerable debate.
The continental crust covers nearly a third of the Earth’s surface. It is buoyant – being less dense than the crust under the surrounding oceans – and is compositionally evolved, dominating the Earth’s budget for those elements that preferentially partition into silicate liquid during mantle melting.
Models for evolution of the crust can provide insights into how and when it was formed, and can be used to show that the composition of the material from which the continental crust is derived is similar to that of the average lower crust. From the late Archaean to late Proterozoic eras (some 3 – 1 billion years ago), much of the continental crust appears to have been generated in pulses of relatively rapid growth.
Reconciling the sedimentary and igneous records for crustal evolution indicates that it may take up to one billion years for new crust to dominate the sedimentary record. Combining models for the differentiation of the crust and the residence time of elements in the upper crust indicates that the average rate of crust formation is some 2 – 3 times higher than most previous estimates.

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RE: The Earth
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Earth lights
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Credit NASA

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The Earth was captured by the Cassini sacecrafte in orbit around Saturn.

The natural colour portrait made possible by the passing of Saturn directly in front of the sun from Cassini's point of view. At the distance of Saturn's orbit, Earth is too narrowly separated from the sun for the spacecraft to safely point its cameras and other instruments toward the Earth without protection from the sun's glare.

PIA08323b
Credit NASA

The Earth-and-moon system is visible as a bright blue point on the right side of the image above centre. Here, Cassini is looking down on the Atlantic Ocean and the western coast of north Africa. The phase angle of Earth, seen from Cassini is about 30 degrees.
A magnified view of the image taken through the clear filter (monochrome) shows the moon as a dim protrusion to the upper left of Earth.



Images taken using red, green and blue spectral filters were combined to create this view. The image was taken by the Cassini spacecraft wide-angle camera on Sept. 15, 2006, at a distance of approximately 2.1 million kilometres from Saturn and at a sun-Saturn-spacecraft angle of almost 179 degrees. Image scale is 129 kilometres per pixel.
At this time, Cassini was nearly 1.5 billion kilometres from Earth.

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