VOA标准英语2014--Scientists Look to Space to Map Ocean Floor

Scientists Look to Space to Map Ocean Floor

More is known about the surface of Mars than the sea floor of our own planet, eighty percent of which is unmapped. That’s changing, though, with the release of a new map based on untapped streams of satellite data.

The new map created by a team at the Scripps Institution of Oceanography at the University of California, San Diego, is twice as accurate as the version produced by the US Navy 20 years ago.  

“The way we’re doing that is to use satellite altimeter, a radar¹, to map the topography of the ocean surface, said Scripps geophysics professor David Sandwell interviewed by SKYPE.

“But now that seems sort of strange that you would map the topography on the ocean surface where you really want to get at the sea floor.  But the ocean surface topography has these bumps and dips due to gravitational effects that mimic² what’s on the sea floor.”    

The scientists pulled data from two satellites, launched for other purposes. The European Space Agency’s Cryo-2 was in the sky to monitor sea ice and NASA’s Jason-1 studied ocean surface. This data set produced the big picture, which was combined with the much finer resolution images captured from ships equipped with multi-beam sonar. “That enables us to look at smaller scale features and also features that are buried by the sediments⁴ in the ocean basins,” said Sandwell.    

Major mountains revealed

The new map shows the fabric⁵ of the seafloor as never seen before with thousands of underwater mountains, ridges⁶ where continents had pulled apart, and extinct earthquake activity buried deep under layers of sediment³.

At one site where three ridges meet, the Earth’s huge thick tectonic plates appear in exquisite⁷ detail. Sandwell said it is called the Indian Ocean Triple Junction⁸, and is one of his favorite spots in the ocean.

“It really displays the theoretical aspects of plate tectonics perfectly⁹. You have three plates, the African plate, and the Indo-Australian plate and the Antarctic plate all connected at this one point in the Center of the Indian Ocean.”

The map exposed continental¹⁰ connections across South America and Africa and showed evidence for seafloor spreading ridges at the Gulf¹¹ of Mexico, active 150 million years ago now under layers of sediment.  

Industry, military, science

Sandwell said the map is a powerful tool for fisheries conservation and for petroleum¹² exploration. “The petroleum industry is interested in how to reconnect the continents, bringing them back together tectonically so you can map the basins on one continental margin¹³ in Africa, and use that to establish where a similar basin would be on the other continental margin in South America.”

Locating oil fields

The data also greatly improves estimates of ocean depths critical for safe navigation, military operations and science missions worldwide, Sandwell adds, “This new gravity map really provides a reconnaissance tool for planning ship board surveys.  You don’t have to go out with your ship and start looking for something new, we can target that with the gravity and then go out with the ship and do the high resolution survey to really understand these features.”

Sandwell expects many more discoveries to emerge as scientists delve¹⁴ into the dataset. The work is described in the current issue of the journal Science.

1 radar   

n.雷达，无线电探测器

参考例句：

• They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
• Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。

2 mimic   

v.模仿，戏弄；n.模仿他人言行的人

参考例句：

• A parrot can mimic a person's voice.鹦鹉能学人的声音。
• He used to mimic speech peculiarities of another.他过去总是模仿别人讲话的特点。

3 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• The sediment settled and the water was clear.杂质沉淀后，水变清了。
• Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。

4 sediments   

沉淀物( sediment的名词复数 )； 沉积物

参考例句：

• When deposited, 70-80% of the volume of muddy sediments may be water. 泥质沉积物沉积后，体积的70-80％是水。
• Oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。

5 fabric   

n.织物，织品，布；构造，结构，组织

参考例句：

• The fabric will spot easily.这种织品很容易玷污。
• I don't like the pattern on the fabric.我不喜欢那块布料上的图案。

6 ridges   

n.脊( ridge的名词复数 )；山脊；脊状突起；大气层的)高压脊

参考例句：

• The path winds along mountain ridges. 峰回路转。
• Perhaps that was the deepest truth in Ridges's nature. 在里奇斯的思想上，这大概可以算是天经地义第一条了。

7 exquisite   

adj.精美的；敏锐的；剧烈的，感觉强烈的

参考例句：

• I was admiring the exquisite workmanship in the mosaic.我当时正在欣赏镶嵌画的精致做工。
• I still remember the exquisite pleasure I experienced in Bali.我依然记得在巴厘岛所经历的那种剧烈的快感。

8 junction   

n.连接，接合；交叉点，接合处，枢纽站

参考例句：

• There's a bridge at the junction of the two rivers.两河的汇合处有座桥。
• You must give way when you come to this junction.你到了这个路口必须让路。

9 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

10 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。

11 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

12 petroleum   

n.原油，石油

参考例句：

• The Government of Iran advanced the price of petroleum last week.上星期伊朗政府提高了石油价格。
• The purpose of oil refinery is to refine crude petroleum.炼油厂的主要工作是提炼原油。

13 margin   

n.页边空白；差额；余地，余裕；边，边缘

参考例句：

• We allowed a margin of 20 minutes in catching the train.我们有20分钟的余地赶火车。
• The village is situated at the margin of a forest.村子位于森林的边缘。

14 delve   

v.深入探究，钻研

参考例句：

• We should not delve too deeply into this painful matter.我们不应该过分深究这件痛苦的事。
• We need to delve more deeply into these questions.这些是我们想进一步了解的。