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  • These are our polar oceans,

  • a part of the world that is more foreign to scientists

  • than the moon or Mars.

  • But we are getting closer to discovering

  • more about these crucial environments

  • with advanced robotic technology.

  • Dr. Alex Forrest is at the forefront of that work.

  • His robots are built to access underneath ice shelves,

  • and to gather data for large-scale maps and models

  • that answer big-picture questions like,

  • "How is a shoreline changing after a storm?"

  • "How is toxic algae spreading?"

  • And, "how fast is polar ice really melting?"

  • The Nansen ice shelf is in Antarctica,

  • down in the Ross Sea,

  • and this ice shelf been an area of interest

  • because it's breaking up.

  • Basically, a piece of ice the size of Manhattan

  • broke off and drifted off, and it exposed,

  • in cross-sectional view, one of these subglacial channels

  • that we've been trying to get access to for a while.

  • We're aiming to go back there again with gliders and AUVs,

  • to try to understand the turbulence

  • and how much energy is being transported through that system.

  • Energy is associated with heat,

  • so if we understand how much heat is in that water,

  • we can understand how much of that heat is coming from the ocean

  • and how much of that is coming from the ice itself.

  • To get a 3D picture of an ecosystem,

  • Alex builds tools including Autonomous Underwater Vehicles, or AUVs

  • with sonar, to make bathymetric maps.

  • He then uses gliders to sample the water column

  • providing him with turbulence, temperature,

  • salinity, chlorophyll and oxygen data.

  • What a glider will do, is move oil around to displace more or less volume

  • to make it heavier or lighter than the water it's in.

  • When it reaches an inflection point, it will pump itself light and then point upwards.

  • The wings create a lift and start drawing it forward.

  • In here is a satellite phone connector, a GPS receiver, and a free wave,

  • or radio receiver.

  • So we can talk to it when it's sitting up on the surface

  • and tell it where to go from anywhere in the world.

  • All together, these chemical and environmental fluid mechanic data

  • create a comprehensive model of this ecosystem.

  • Exploring these icy frontiers is a balancing act

  • of keeping people and equipment safe in extreme weather and ocean conditions,

  • bringing back accurate data,

  • and preserving the very delicate ecosystem we want to study.

  • One of the biggest challenges underwater is that we don't have positioning.

  • We don't have WiFi, we can't get radio signals through, we don't have GPS...

  • all of these tools that we use in regular, terrestrial mapping.

  • You're basically guessing where you are underwater, so you need to develop navigation algorithms

  • if you're using an underwater vehicle.

  • Now, you put that on a ship, and then s@$%,

  • you all of a sudden are influenced by the waves.

  • So the waves, storms, et cetera will then modify how your data looks.

  • What we don't want to happen is to have our vehicle modify the fragile ecosystem that

  • exists at this water-ice interface.

  • Despite these challenges, Alex and his team continue to gather this data

  • as it is one of the clearest examples of how the planet's climate

  • is changing every day.

  • The polar regions are changing faster than anybody ever predicted.

  • It's not just a matter of large pieces of ice shelves collapsing.

  • What I find more intimidating is the idea that our sea ice volume

  • is at some of the lowest it's ever been before;

  • that the Arctic ocean temperatures are getting warmer

  • than ever before; that all of a sudden,

  • air temperatures are getting hotter.

  • So we need to know the baseline conditions of today if we're to predict how they're gonna

  • change and evolve in the future,

  • and also to understand as a global community

  • what we're losing.

These are our polar oceans,

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B1 中級

探索極地冰蓋下所需的一切努力 (Everything It Takes to Explore Beneath Polar Ice Caps)

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    林宜悉 發佈於 2021 年 01 月 14 日
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