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Information about ocean temperatures is important for climate change, but data are rare in the Indian Ocean
Scientists have come up with a clever new way to measure ocean temperature, using sound waves from underground earthquakes.
Researchers say the “hack” works because the sound travels faster in hot water.
The team looked at the sonic data of the Indian Ocean, which was released by vibration over a period of 10 years.
Scientists have seen an increase in the speed of sound waves as the oceans get warmer due to global warming.
His new method shows that the trend of decadal warming in the Indian Ocean was much higher than previously estimated.
Climate scientists need to have accurate information about the temperature of our oceans.
They understand that about 90% of the energy trapped in our atmosphere by greenhouse gases is absorbed by the oceans.
But accurate measurement of temperature in multiple places and ths depths is a big challenge.
The deployment of about 4,000 autonomous devices called Argo Floats, which receive temperature information, has been very helpful, but there are many major shortcomings in our knowledge.
This is especially true in relation to what is happening in waters deeper than 2,000 mm.
But now a team of researchers has developed a very different approach that uses the fact that the speed of sound in seawater depends on temperature.
The idea was first proposed using sound waves produced by scientists and was developed in the late 1970s.
However, concerns about the impact of these noises on marine mammals and rising costs left the idea.
The new approach involves the use of naturally occurring sound waves that occur during groundwater earthquakes.
Scientists examined data on more than 4,000 tremors in the Indian Ocean between 2004 and 2016.
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Researchers record time taken for sound waves to register on Diego Garcia after a trip to the Indian Ocean
The team then discovered a pair of “repeaters”, earthquakes with almost the same origin and power.
By measuring how long these slow moving signals took to travel from India to a monitoring station on Diego Garcia Island, they could help change the temperature across the ocean over a 10-year period. .
Leading author of the California Institute of Technology, Dr. The journey from Sumatra to Diego Garcia takes about half an hour, Venbo Wu told BBC News.
“This half-hour journey time varies from a few tenths of a second due to changes in the temperature of the deep sea between Sumatra and Diego Garcia.
“Because we can measure these variations very accurately, we can estimate small changes in the average temperature of the deep ocean, in this case, about a tenth of a degree.”
The author says that the system has some major advantages, as it is able to provide massive average temperatures along the 3,000-kilometer route from Sumatra to Diego Garcia, reducing the influence of local fluctuations, essentially making it more accurate at sea. The whole.
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Indonesian students train for tsunami due to earthquake, which is always a risk
This method is also very inexpensive, as it uses data that is already collected, and is sensitive to tion deeper temperatures than the current restriction of 2,000,000 m.
In their research, the scientists showed that the temperature they studied during the decade in the Indian Ocean was higher than previously estimated.
However, the paper has some important warnings.
Dr Wu said it was important to emphasize that this is the result that applies to this particular area and this particular decade.
“We need to apply our method in many more regions and over different periods to assess whether there is a systematic under-ost-estimation of the deep sea trend globally.
“It’s too early to draw any conclusions in this direction.”
To make this idea work globally, scientists will need more water receivers.
Currently, the research team is working with data collected through a hydrophone network operated by the Comprehensive Nuclear-Ban Treaty Organization of the United Nations, which is listening for underwater nuclear explosions.
These hydrophones take many signals from the 10,000 shallow submarine earthquakes that occur globally each year, Dwu explained.
“All of this data includes information about changes in the temperature of the ocean deep sea – it will just wait for it to ract.”
The study is published in the journal Science.
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