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  • In recent news, floating robots and elephant seals joined a scientific research team to

  • help solve a mystery about our polar seas.

  • Ok, there are giant, recurring holes called polynyas that tend to pop up in both the Arctic

  • and Antarctic that scientists just did not understand.

  • And no, these aren't caused by the regular old melting of the ice caps, they're a long-standing,

  • well-documented, mysterious and surprising aspect of polar sea ice.

  • They're essential to these ecosystems for many reasons and are fascinating because under

  • the circumstances, scientists would expect there to be a thick chunk of ice there...but

  • there's not.

  • Instead, there's a big hole opening into the ocean underneath.

  • The polynya these researchers studied in particular is an open-ocean polynya, meaning it vanishes

  • every summer when the sea ice melts, and SOME years it'll randomly reappear in the same

  • spot when the ice reforms...But sometimes not.

  • We know a little bit about how these kinds of polynyas are maintained, but haven't

  • known that much about how they form in the first place.

  • The formation of this gaping hole that has ranged from the size of New Zealand to the

  • size of South Carolina doesn't seem to be related to changes in temperature, or other

  • factors that would seem obvious.

  • To explore the whole range of complex variables that could be at play in forming this polynya,

  • a research team at the University of Washington decided to analyze massive amounts of data

  • that gave them a pretty comprehensive view of both the ocean and the ice for a period

  • of several years.

  • The essential tool in making this project happen?

  • FLOATING ROBOTS.

  • These novel bots are actually a really exciting tool being used in oceanography because they

  • can remotely record all kinds of data: the temperature, salinity, ocean currents, and

  • exciting new developments in biochemical sensor technology allow them to take readings of

  • oxygen and nitrogen levels, acidity, and lots of other complex biological and chemical factors.

  • And they can dive a few kilometers below the ocean's surface, getting readings on what

  • the ocean is like in the middle of winter, when it would be too expensive and even dangerous

  • for researchers to get there by boat.

  • So...why do we need the seals?

  • Lest we forget, temperature, salinity, and other measurements were also gathered from

  • elephant seals wearing sensors.

  • Seals have access to the same parts of the ocean that the bots do, but the seals took

  • data in years when the polynya didn't show up, and there was no hole in the ice.

  • So the researchers could compare ocean conditions between years with and without polynyas.

  • As a result of all this awesome data, the researchers found that increases in salinity

  • and strong storm activity are likely the formative factors for this mysterious polynya.

  • Both storms and increased salinity cause warmer water to rise to the surface and melt a hole

  • in the ice.

  • The reason the polynya keeps forming in the same place is because of the underwater topography:

  • it's right above an undersea mountain!

  • This traps that warm water there like a vortex, keeping this polynya from closing back up.

  • AND if you're wondering what the seals thought about all thissensors like this are attached

  • using a special kind of glue that lets the sensor fall off after a few months, after

  • which the seals can go back to their day job of just...being seals.

  • Polynyasbesides being mysterious puzzles to oceanographersare essential parts of

  • polar ecosystems.

  • They provide a bridge between ice and ocean for many polar animals, like seals and penguins.

  • Because they let sunlight into spots in the ocean that would otherwise be covered by ice,

  • polynyas provide ideal conditions for phytoplankton, which are the bottom link in the marine food

  • chaineverything else in the ocean depends on their existence. And polynyas pour heat

  • and moisture out of the sea and into the local atmosphere, changing the weather of their

  • immediate vicinity.

  • And climate change is associated with a decrease in ocean salinity and increase in severity

  • and unpredictability of severe weather events, both of the factors that play a major role

  • in polynya formation.

  • So while the researchers don't know if the expected changes in climate will increase

  • or decrease the instances of polynyas, they're definitely pretty sure polynya behavior will

  • be disturbed.

  • Which may influence local weather patterns and ocean currents in ways that reverberate

  • into the rest of the world's oceans and the wider climate patterns.

  • And in order to understand just how this could affect Antarctic wildlife and sea ice dynamics,

  • researchers say they can use results from studies like this to improve the models and

  • simulations that help us know what to expect, and how we can prepare.

  • Want to know more about what's lurking under the ice at the bottom of the globe?

  • Make sure you subscribe, and check out this video on the dead continents underneath Antarctica

  • over here, and keep coming back to Seeker for all your ocean science news.

  • As always, thanks for watching and we'll see you next time.

In recent news, floating robots and elephant seals joined a scientific research team to

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科學家們離解開南極之謎又近了一步。 (Scientists Just Got One Step Closer to Solving an Antarctic Mystery)

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    林宜悉 發佈於 2021 年 01 月 14 日
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