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#1 05-12-2018 01:22:02

zhouyueyue
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Date d'inscription: 10-07-2018
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Bryant injured his lateral tibial plateau in

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SAN FRANCISCO, Jan. 16 (Xinhua) -- A new research shows the fierce winds circling Antarctica, an important lever on the global climate, shifted quickly in response to the Northern Hemisphere temperature spikes during the last ice age, tens of thousands of years ago.


The findings, published in the January issue of Nature Geoscience, were based on evidence from a West Antarctic ice core 2 miles, or 3.2 kilometers, in length. The ice core's thick annual layers provide precise dating that allows researchers to match its climate history with those in distant Greenland ice records.


During the last ice age, as part of a dramatic pattern in our planet's climate history, which involves paroxysms in Arctic temperatures, Greenland repeatedly warmed by about 10 degrees Celsius over just a few decades and then gradually cooled, while the Southern Hemisphere climate stayed fairly stable, with only weak and long-delayed echoes of the temperature chaos up north.


The wild northern temperature swings, known as Dansgaard-Oeschger events, are thought to be natural oscillations in the climate system.


The Antarctic ice core shows that Southern Ocean winds shifted at the same time, or at most within a few decades, of each rapid Greenland warming event. Antarctic air temperatures, on the other hand, are connected through the slower-moving oceans and took about two centuries to respond.


""We'd never found anything in our ice cores before that show the Southern Hemisphere responding so quickly to what happened in the Northern Hemisphere,"" said the study's co-author Eric Steig, a University of Washington (UW) professor of Earth and space sciences. ""What we found is that when it warms up abruptly in the Northern Hemisphere, the winds in the Southern Hemisphere move north, and blow over warmer water. And the opposite happens when it cools down quickly in the north: the winds shift south.""


It was well known that tropical rain bands and the Northern Hemisphere jet stream adjust to the temperature balance between hemispheres. But there was little historical evidence for winds blowing over the icy southern seas.


The new study uses chemical clues in the 70,000-year ice core record. As gusting winds evaporate seawater, the fraction of heavier to lighter hydrogen and oxygen atoms in vapor depends on the ocean's temperature. When this moisture eventually falls as snow over Antarctica, it contains a signature of the latitude where it evaporated.


""It's most surprising that we can see these really abrupt changes in the Northern Hemisphere making it very quickly to the Southern Hemisphere,"" said first author Bradley Markle, a UW doctoral student in Earth and space sciences.


Results show that the winds shifted north toward the equator when Greenland warmed, through a signal that was communicated through the atmosphere. ""When it warms up rapidly in the Northern Hemisphere it creates strong temperature gradients, which influence the rain belts in the tropics. The rain belts in the tropics affect where the winds blow in the Southern Hemisphere. So it's a chain of effects,"" Steig said.


Besides being important for Antarctic climate, the Southern Ocean winds influence rainfall in South America, Australia and southern Africa, and also play a role in long-term climate feedbacks that involve Antarctic sea ice and the uptake of atmospheric carbon dioxide by the oceans.


""There's a general understanding in the climate science community that global warming is not just about temperature change, it's also about changing winds,"" Steig was quoted as saying in a news release.


While there is some evidence that Southern Ocean winds may be changing today, the causes would be different from those in the study, the authors cautioned. However, the results establish a new bridge between the two hemispheres, and support the results from computer models that create detailed simulations of the global climate over thousands of years.

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WASHINGTON Cheap Ryan Anderson Jersey , March 12 (Xinhua) -- Five-time NBA title holder Kobe Bryant would miss all of the rest games in 2013-2014 season due to the left knee injury, announced the Los Angeles Lakers on Monday.


Bryant injured his lateral tibial plateau in his left knee on Dec. 17 last year during the Lakers' 96-92 victory over the Memphis Grizzlies. He had been expected to miss six weeks, but after a re-examination Feb. 21 his doctor found Bryant would need three more weeks. The 18-year veteran had another re-exam on Monday Cheap Eric Gordon Jersey , only to find his left knee still hadn't been fully healed.


"Obviously this has been a frustrating and disappointing season, but I appreciate all the support I've received from the Lakers and the fans, and look forward to being back and ready for the start of training camp Cheap Chris Paul Jersey ," said Bryant in the news release.


Bryant had been kept away from the court for as many as 240 days last year because of his left ankle injury, and he missed the first 19 games at the beginning of the 2013-2014 season. He came back on Dec. 9, but the left knee injury forced him out again after six games. The 35-year-old had averaged 13.8 points Cheap Trevor Ariza Jersey , 4.3 rebounds and 6.3 assists for the Lakers in that six games.


The Lakers inked a two-year, 48.5 million dollars contract with Bryant last November.


According to the current contract, which would expire until the end of this season Cheap Hakeem Olajuwon Jersey , the Lakers had to pay Bryant's entire 30.453 million salary for the 2013-14 season.


JERUSALEM, Sept. 28 (Xinhua) -- Two Arab citizens of Israel were indicted Thursday for planning to carry out a shooting attack in East Jerusalem's Al-Aqsa Mosque compound, said Israel's Shin Bet security service.


The Shin Bet identified them as Said Gasub Mahmoud Jabarin Cheap James Harden Jersey , 26, and a 16-year-old minor, whose name was not disclosed. They are both residents of Umm al-Fahm Cheap Houston Rockets Hats , an Arab city in central Israel, from which three gunm. Cheap Jerseys   Cheap Jerseys From China   Cheap Jerseys From China   Cheap Jerseys   Cheap Jerseys China   Cheap MLB Jerseys   Cheap NHL Jerseys   Cheap Jerseys Wholesale   Cheap Away Jerseys   Wholesale Hats China

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