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Recording infrasound on land is not particularly tricky. You can place the sensor almost anywhere. This is not the case in the oceans of the southern hemisphere: sensors can only be placed on most remote islands, so the coverage is poor.
Moreover, den Ouden said that in the open ocean, “huge waves” can generate a lot of unwelcome noise. When the shaking sea waves interact, some irritating infrasound will be produced. “The ocean began to rise and fall rhythmically,” den Ouden said. The sea is like a huge loudspeaker, spraying energy into the atmosphere, propagating upwards, across the water, and moving towards the land, like invisible tidal waves. Other ocean infrasounds are less problematic, but more mysterious: the motion of the ocean triggers atmospheric vibrations that radiate directly upwards. But it turns out that these waves are so difficult to detect that their existence has been an open question for a long time.
These infrasound waves are technically called micro-pressure, and are called “The sound of the sea. “Most researchers want to submerge it. “We are trying to eliminate the low-pressure signal because we are interested in explosions,” Iezzi said.
Ideally, infrasound detectors at sea can not only fill in the huge coverage gap, but also record the micro-pressure well. With the help of filtering software, they can be effectively eliminated. But where would you put these detectors? The boat doesn’t work. “The problem with them is that they keep moving up and down,” Lamb said-this affects the recording. Balloons have been used to record infrasound on land, but their flight paths over the sea are too unpredictable and useless. (However, they are useful for recording lightning strikes, earthquakes, and volcanic eruptions On venus, Because the surface of the evil twins on the earth is too hot, any instruments placed on the ground will quickly melt. Or, at least, overheating. )
The open ocean is “a very challenging place to record sound,” Bowman said. “In fact, it is so challenging. If you asked me before reading this paper, I would say that it is basically impossible.”
When it happens, Samantha PatrickSeabird ecologists at the University of Liverpool are curious about the ability of seabirds to use infrasound navigation. After talking with den Ouden and his colleagues who specialize in weather and geophysics, they came up with a strange idea: Why not install microbarometric detectors on birds? Not just any bird: Wandering Albatross. Their wingspan can be 11 feet long, which is longer than anyone’s height. This allows them to spend a lot of time simply floating in the air currents above the open water, which saves energy when they begin their foraging trip. Not only do they fly over large isolated oceans, but they do not dive into the water, so any sensors connected to them will not become particularly wet.
Soon, the researchers made tiny infrasound sensors and packed them into small bags—the packaging was no heavier than the TV remote control. Although it may be interesting to imagine these bags being dragged like schoolchildren carrying backpacks, it would have been unnecessary complication. Instead, these pouches are just glued to the back of the bird assistant with some tape.
Last year, the team went to the Crozet Islands, a small piece of land in France’s sub-Antarctica where wandering albatross like to build nests. But, how do you get the albatross to cooperate?Use one Very special hug, Obviously-can prevent any potentially harmful slapping and pecking. “They have no real predators-certainly no natural predators,” said Patrick, who assisted the team in the research. “So you really just walk up to it and put your hand on its bill, and then you have to hug it because it is too big. You give it a hug, lift it off the lair, and then hold it alone , And then another person taped the recorder to their back.”
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