成員之一、來自丹麥技術大學(Technical University of Denmark)的克里斯?芬雷(Chris Finlay)說：「我們了解太陽比了解地球核心還多。對於更加了解地球內部的活動，這個噴射流的發現，是令人興奮的一步。」
芬雷和研究小組在分析來自歐洲太空總署(European Space Agency，ESA) 名為蜂群(Swarm)的三顆衛星數據時，發現到這個噴射流。
來自英國里茲大學(University of Leeds)的首席研究員菲爾?利福摩爾(Phil Livermore)說：「歐洲太空總署的蜂群衛星正在提供最清晰的X射線核心照片。」
Earth s Core
當研究人員檢視來自北半球外核心區域的衛星數據時，發現在阿拉斯加和西伯利亞底下有奇怪的磁流 波瓣(lobe) 。
安迪?柯格林(Andy Coghlan)為新科學人(New Scientist)雜誌寫報導：「因為它們的移動只可能來自於鐵水的物理運動，因此波瓣被當作標記，允許研究人員跟蹤鐵水的流動。」
歐洲太空總署的群蜂任務經理魯尼?弗萊博哈根(Rune Floberghagen) 在一份新聞稿聲明中說：「更多的驚奇是有可能的。」
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一條快速流動的鐵水(molten iron)河被發現在阿拉斯加和西伯利亞底下奔騰，大約在地底下3千公里(1,8 …
Source: 一條巨大的液態鐵「噴射流」 在地球內部發現 – iFuun
SCIENCE 12/22/2016 @ 12:11下午 62,099 views
A Liquid Iron Jet Has Surrounded Earth’s Core And Is Accelerating
A recent major discovery identified a massive liquid iron “jet stream” circling the Earth’s outer core that appears to be accelerating. This comparatively fast flowing liquid iron stream is currently moving westward under Alaska and Siberia as measured by the Swarm satellites and recently published in Nature Geoscience.
The iron jet is moving at about 50 km per year, orders of magnitude faster than plates move and much faster than anything scientists knew of within Earth’s interior. Traveling at 50 km per year doesn’t seem rather fast compared to speeds on the surface of the Earth. However, consider the tremendous amount of energy required to push aside dense liquid metal under very high pressures across hundreds of miles. In addition, it appears that this liquid jet stream is accelerating but scientists have not determined what is causing the acceleration.
The liquid iron jet is similar to the jet stream found within our atmosphere but at 3,000 km below the surface of the Earth. The jet appears to be 420 km wide and covers half way around the planet as it travels through Earth’s liquid outer core. This iron jet has likely been circling the Earth for hundreds of millions of years, yet we just discovered its existence. Despite a good understanding of the iron jet’s width and length, the depth to which it extends is far from known.
The liquid jet likely aligns between two different boundaries within Earth’s core. The boundary, which the research team calls a “tangent cylinder” is like a tube running along the solid inner core along Earth’s rotational axis. When molten iron travels toward the cylinder it is diverted sideways and forms a jet along the theoretical tube.
As part of the Swarm program, a trio of three spacecraft were launched in 2013 to circle and map the Earth’s magnetic field in 4 dimensions. Scientists are now able to measure spatial changes with time in Earth’s magnetic field from the European Space Agency’s Swarm satellite program. The three satellites allow unprecedented high resolution magnetic field measurements. This allows scientists to examine the structure of Earth’s interior and the dynamic behavior of its magnetic field through time.
The ultimate goal of Swarm is to measure and quantify why Earth’s magnetic field has continuously weakened in the past centuries. The fear is that Earth may be close to a magnetic reversal, whereby the magnetic north flips from its current position near the North Pole to the South Pole. Geologists can measure past pole reversals, which happen every couple hundred thousand years, and note the significant impact this has on climate and population dynamics.
Understanding and monitoring the movement of this liquid iron jet will hopefully shed light on the current state of the liquid core, how it behaves, and the likelihood of an imminent global magnetic reversal.
Trevor Nace is a geologist, Forbes contributor, and adventurer. Follow him on Twitter @trevornace
Iron ‘jet stream’ detected in Earth’s outer core
19 December 2016
- From the section Science & Environment
Scientists say they have identified a remarkable new feature in Earth’s molten outer core.
They describe it as a kind of “jet stream" – a fast-flowing river of liquid iron that is surging westwards under Alaska and Siberia.
The moving mass of metal has been inferred from measurements made by Europe’s Swarm satellites.
This trio of spacecraft are currently mapping Earth’s magnetic field to try to understand its fundamental workings.
The scientists say the jet is the best explanation for the patches of concentrated field strength that the satellites observe in the northern hemisphere.
“This jet of liquid iron is moving at about fifty kilometres per year," explained Dr Chris Finlay from the National Space Institute at the Technical University of Denmark (DTU Space).
“That might not sound like a lot to you on Earth’s surface, but you have to remember this a very dense liquid metal and it takes a huge amount of energy to move this thing around and that’s probably the fastest motion we have anywhere within the solid Earth,” he told BBC News.
Dr Finlay was speaking here at the American Geophysical Union (AGU) meeting in San Francisco, just ahead of the official publication of the research in the journal Nature Geoscience.
Most people will be familiar with the atmospheric jet stream – the high-altitude, rapidly flowing belt of air on which aeroplanes ride to get to their destination more quickly.
Dr Finlay and colleagues want us to envision something similar but made of metal and 3,000km down, under our feet.
They assess the jet to be about 420km wide, and say it wraps half-way around the planet.
Its behaviour will be critical to the generation and maintenance of the global magnetic field, they add.
“It’s likely that the jet stream has been in play for hundreds of millions of years," said Dr Phil Livermore from Leeds University, UK, and the lead author on the journal paper.
In the paper, the team puts forward a model to explain the jet.
The scientists say the feature probably aligns to a boundary between two different regions in the core.
They call this boundary the “tangent cylinder". They imagine this as a tube sitting around the solid inner core, running along Earth’s rotation axis.
When liquid iron approaches the boundary from both sides, it gets squeezed out sideways to form the jet, which then hugs the imaginary tube.
“Of course, you need a force to move fluid towards the tangent cylinder," said Prof Rainer Hollerbach, also from Leeds and another co-author on the paper.
“This could be provided by buoyancy, or perhaps more likely from changes in the magnetic field within the core."
Although the team believes it understands how wide and how long the jet is, the depth to which it descends is far from certain.
Dr Livermore told BBC News: “It currently wraps about 180 degrees around the tangent cylinder. Although observations only constrain the jet stream on the edge of the core, our theoretical understanding suggests that the jet could in principle go very deep indeed – possibly in fact all the way down to the edge of the core in the southern hemisphere (i.e. at the other end of the tangent cylinder)."
That the team can make such inferences speaks to the impressive capabilities of the Swarm constellation.
Launched in November 2013, the European Space Agency satellites are providing unparalleled insights into the structure and behaviour of Earth’s magnetic field.
With their highly sensitive instruments, they are gradually teasing apart the field’s various components – from the dominant signal coming from the movement of iron in the outer core to the almost imperceptible contribution made by ocean currents.
It is hoped the Swarm satellites’ data could ultimately tell us why Earth’s magnetic field has been weakening in recent centuries.
Scientists have speculated we could be on the cusp of a polarity reversal, which would see North become South, and South become North.
This occurs every few hundred thousand years.