VOA标准英语2011--Scientists to Drill Huge Hole in Antarctic Ice

Scientists to Drill Huge Hole in Antarctic Ice

 

Antarctica is the largest reservoir of glacial ice on the planet. An expedition of international scientists is headed to the frozen continent to study why its glaciers² are retreating so fast.

What they find could help predict Antarctica’s anticipated big melt more accurately³, a consequence of climate change that will significantly raise global sea levels over the coming century.

The focus is Pine Island Glacier¹, a mass of ice 2,300 square kilometers across and 500 meters deep. Melting in this region of western Antarctica is responsible for seven percent of the recorded sea level rise over the past few years.

A massive crack running about 29 kilometers across Pine Island glacier’s floating tongue, taken during flight over region late October 2011.

Team leader and U.S. Space Agency glaciologist Robert Bindschadler says, “This is where Antarctica is hemorrhaging ice and raising sea level.” Pine Island Glacier is melting most rapidly underneath⁴ its ice shelf that sticks out into the ocean, Bindschadler says. “And we’re anticipating melt rates of, in some places, of over 100 meters per year, which are just phenomenally high.”

Bindschadler says the melt is triggered by the interaction of wind, water and ice, with heat rising from a cavity beneath the ice sheet. He says while satellites can map the glacier and chart its movement, they cannot measure what is going on under the ice shelf and in the cavity.

“The details of this we do not know. That’s what our measurements are going to tell us,” he says.

Near U.S. Antarctic McMurdo station scientists practice lowering the ocean profiler down a hole into the ocean beneath the ice.

To gather data on water circulation, currents and ice flow in the ocean cavity, the team must first drill a hole in the ice. Naval⁵ Postgraduate⁶ School oceanographer Timothy Stanton says given the extreme conditions that prevail in Antarctica, the drilling is done with lo-tech simplicity⁷.

“Basically this system makes a 27-centimeter-diameter hole through this 500-meter-thick ice shelf, using pumped hot water. In a sense it’s very primitive⁸. It’s a very labor⁹ intensive, simple system because we had to be light and portable to get this far into the deep field.”

After the drill hits water, the scientists will send a camera down to observe the underbelly of the ice shelf and the seabed below it. Stanton says the team will also deploy¹⁰ a profiler, a device that moves up and down on a tight cable and can measure temperature, salinity¹¹ and currents from below the ice to just above the sea floor.

A field test of the drilling system near McMurdo station during the 2010-11 Antarctic field season.

“Then using precision depth sensors¹² and an altimeter we can infer directly the local melt rates of the ice sheet above us. This warming is hypothesized to change the strength of the ice shelf and is very important for modeling the actual glacial properties of the ice shelf over time.”

A similar instrument array fixed¹³ to a pole will be attached to the underside of the ice shelf in a second hole. The team will determine the shape of the ocean cavity with sonar equipment. They plan to set off small explosions and bang on the ice with instruments like sledgehammers, and follow the sound waves as they echo back through the ice, water column and bed rock.

Pine Island Glacier is located 2,200 kilometers from the nearest neighbor at the U.S. McMurdo research station. The station will be powered by wind generators¹⁴, solar panels, and a bank of lithium batteries that Stanton says will allow his research colleagues back at the Naval Postgraduate School in San Diego, California to maintain communications with the expedition. “And every day can modify the sampling strategy.”

In 2008, expedition leader Robert Bindschadler was the first to set foot on the Pine Island Glacier ice shelf.

The expedition is funded by the National Science Foundation and the U.S. space agency, NASA. Oceanographer Stanton says the findings can help improve the accuracy of climate models for predicting ice sheet melt and sea level rise in the most rapidly changing environment on the planet.

1 glacier   

n.冰川，冰河

参考例句：

• The glacier calved a large iceberg.冰河崩解而形成一个大冰山。
• The upper surface of glacier is riven by crevasses.冰川的上表面已裂成冰隙。

2 glaciers   

冰河，冰川( glacier的名词复数 )

参考例句：

• Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
• It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川，又有雨林和秀丽的山峰。 来自英语晨读30分（高一）

3 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

4 underneath   

adj.在...下面，在...底下；adv.在下面

参考例句：

• Working underneath the car is always a messy job.在汽车底下工作是件脏活。
• She wore a coat with a dress underneath.她穿着一件大衣，里面套着一条连衣裙。

5 naval   

adj.海军的，军舰的，船的

参考例句：

• He took part in a great naval battle.他参加了一次大海战。
• The harbour is an important naval base.该港是一个重要的海军基地。

6 postgraduate   

adj.大学毕业后的，大学研究院的；n.研究生

参考例句：

• I didn't put down that I had postgraduate degree.我没有写上我有硕士学位。
• After college,Mary hopes to do postgraduate work in law school.大学毕业后， 玛丽想在法学院从事研究工作。

7 simplicity   

n.简单，简易；朴素；直率，单纯

参考例句：

• She dressed with elegant simplicity.她穿着朴素高雅。
• The beauty of this plan is its simplicity.简明扼要是这个计划的一大特点。

8 primitive   

adj.原始的；简单的；n.原(始)人，原始事物

参考例句：

• It is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
• His book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。

9 labor   

n.劳动，努力，工作，劳工；分娩；vi.劳动，努力，苦干；vt.详细分析；麻烦

参考例句：

• We are never late in satisfying him for his labor.我们从不延误付给他劳动报酬。
• He was completely spent after two weeks of hard labor.艰苦劳动两周后，他已经疲惫不堪了。

10 deploy   

v.（军）散开成战斗队形，布置，展开

参考例句：

• The infantry began to deploy at dawn.步兵黎明时开始进入战斗位置。
• The president said he had no intention of deploying ground troops.总统称并不打算部署地面部队。

11 salinity   

n.盐分；咸度；盐浓度；咸性

参考例句：

• In the sea water sampled the salinity is two parts per thousand.在取样的海水中，盐度为千分之二。
• In many sedimentary basins the salinity of the formation water increases with depth or compaction.在许多沉积盆地中，地层水的含盐量随深度或压实作用而增高。

12 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

13 fixed   

adj.固定的，不变的，准备好的；(计算机)固定的

参考例句：

• Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？
• Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

14 generators   

n.发电机，发生器( generator的名词复数 )；电力公司

参考例句：

• The factory's emergency generators were used during the power cut. 工厂应急发电机在停电期间用上了。
• Power can be fed from wind generators into the electricity grid system. 电力可以从风力发电机流入输电网。 来自《简明英汉词典》