18 nautical raster charts updated
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Saturday, June 20, 2020
Breathing the ocean
Take a deep breath.
In "Breathing the Ocean", a short film in which she raises her voice, Julie Gautier raises the question of the essential role of phytoplankton in the planetary ecosystem.
After "Into The Depths", a film that raises awareness of the pollution of the aquatic ecosystem, the Biotherm skincare brand wanted to put the spotlight on the importance of plant plankton by featuring the famous film director, freediver and dancer from Reunion Island.
Forests play an essential role in the well-being of the planet, but it is the phytoplankton that are considered a true blue lung.
In fact, more than half of the oxygen produced on Earth comes from these plant organisms living in suspension in the water.
And if it is too small to be seen with the naked eye, large, colourful expanses of phytoplankton can be seen on the surface of the water when they congregate in sufficient numbers and emit light.
A phenomenon that testifies to the immensity of the subject, as Julie Gautier reminds us:
"So small you can't see it, so big you can't imagine it."
"It's simply because of them that we can breathe."
And if the directors wanted to raise awareness about the beauty and importance of the links between climate and plant plankton, it is because they are in danger.
Threatened by plastic pollution of the oceans, climate change and environmental upheavals, the quantity of phytoplankton is decreasing by 1% every year and 40% have even disappeared since 1950.
Then yes, art can be engaged.
After "Into The Depths", a film that raises awareness of the pollution of the aquatic ecosystem, the Biotherm skincare brand wanted to put the spotlight on the importance of plant plankton by featuring the famous film director, freediver and dancer from Reunion Island.
Forests play an essential role in the well-being of the planet, but it is the phytoplankton that are considered a true blue lung.
In fact, more than half of the oxygen produced on Earth comes from these plant organisms living in suspension in the water.
And if it is too small to be seen with the naked eye, large, colourful expanses of phytoplankton can be seen on the surface of the water when they congregate in sufficient numbers and emit light.
A phenomenon that testifies to the immensity of the subject, as Julie Gautier reminds us:
"So small you can't see it, so big you can't imagine it."
"It's simply because of them that we can breathe."
And if the directors wanted to raise awareness about the beauty and importance of the links between climate and plant plankton, it is because they are in danger.
Threatened by plastic pollution of the oceans, climate change and environmental upheavals, the quantity of phytoplankton is decreasing by 1% every year and 40% have even disappeared since 1950.
Then yes, art can be engaged.
Friday, June 19, 2020
Cuba (GeoCuba) layer update in the GeoGarage platform
11 nautical raster charts updated
see GeoGarage news
see Geographicus
A satellite lets scientists see Antarctica’s melting like never before
Sources: NASA ICESat and ICESat-2
From NYTimes by Kendra Pierre-Louis, Henry Fountain and Denise Lu
New data from space is providing the most precise picture yet of Antarctica’s ice, where it is accumulating most quickly and disappearing at the fastest rate, and how the changes could contribute to rising sea levels.
The information, in a paper published on Thursday in the journal Science, will help researchers better understand the largest driver of ice loss in Antarctica, the thinning of floating ice shelves that allows more ice to flow from the interior to the ocean, and how that will contribute to rising sea levels.
Researchers have known for a long time that, while the continent is losing mass over all as the climate changes, the change is uneven.
It is gaining more ice in some areas, like parts of East Antarctica, and losing it quickly in others, in West Antarctica and the Antarctic Peninsula.
Helen A. Fricker, an author of the paper, said that scientists have tried to study the link between thinning shelves and what is called grounded ice, but have been hampered because most observations were of one area or the other, and made at different times.
“Now we’ve got it all on the same map, which is a really powerful thing,” said Dr. Fricker, a glaciologist at the Scripps Institution of Oceanography in La Jolla, Calif.
Using the most advanced Earth-observing laser instrument NASA has ever flown in space, scientists have made precise, detailed measurements of how the elevation of the Greenland and Antarctic ice sheets have changed over 16 years.
The results provide insights into how the polar ice sheets are changing, demonstrating definitively that small gains of ice in East Antarctica are dwarfed by massive losses in West Antarctica.
The scientists found the net loss of ice from Antarctica, along with Greenland’s shrinking ice sheet, has been responsible for 0.55 inches (14 millimeters) of sea level rise between 2003 and 2019 – slightly less than a third of the total amount of sea level rise observed in the world’s oceans.
The Ice, Cloud and land Elevation Satellite-2, or ICESat-2, was launched in 2018 as part of NASA’s Earth Observing System.
It replaced a satellite that had provided data from 2003 to 2009.
ICESat-2 uses a laser altimeter, which fires pulses of photons split into six beams toward the Earth’s surface 300 miles below.
Of the trillions of photons in each pulse, only a handful of reflected ones are detected back at the satellite.
Extremely precise measurement of these photons’ travel times provides surface elevation data that is accurate to within a few inches.
“It’s not like any instrument that we’ve had in space before,” said another of the authors, Alex S. Gardner, a glaciologist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
The resolution is so high that it can detect rifts and other small features of the ice surface, he said.
The coast of West Antarctica is rapidly losing mass as warm water melts ice shelves from below and icebergs break off.
The researchers used the elevation measurements from both satellites to determine how Antarctica’s mass balance, the difference between accumulation and loss, changed from 2003 to 2019 for each of its 27 drainage basins.
Over all, they reported that the continent had lost enough ice to raise sea levels by six millimeters, or about one-quarter of an inch, during that time period.
While that finding is consistent with other studies that used data from other instruments, “in a lot of ways this is a more definitive measurement,” said Ben Smith, a glaciologist at the University of Washington and an author of the study.
“It shows a set of differences that we can really understand in detail and know what they mean for the ice sheets.”
Ice loss was limited to West Antarctica and the Antarctic Peninsula; the bigger East Antarctic sheet gained mass over that time.
The East Antarctic increase is likely because of increased precipitation, Dr. Gardner said.
“While we can’t say that these changes are related to contemporary climate change, we can say that these are the patterns of change we expect to see in a warming world,” he said.
Increased precipitation in the form of snow leads to an increase in ice sheet mass because, as snow compresses over time, it turns to ice.
Floating ice shelves accounted for 30 percent of the ice loss in West Antarctica, the researchers found.
Floating ice is lost in two ways: by calving of icebergs and through melting from underneath by a deep current of warmer water that circulates around the continent.
Floating ice is, by definition, already in the water, so when it calves or melts it does not add to sea level rise.
But ice shelves act as buttresses against the grounded ice behind them; when they thin they allow that ice to flow faster.
And when the previously grounded ice reaches the water, it adds to rising seas.
Scientists are increasingly concerned that the loss of floating ice in West Antarctica is causing more rapid flow of grounded ice in the West Antarctic ice sheet, and that a portion of the sheet could collapse over centuries, greatly increasing sea levels.
The study looked at changes in the Greenland ice sheet as well.
Unlike Antarctica, where little ice is lost through surface melting and runoff, as much as two-thirds of Greenland’s ice is lost this way.
Using data from the ICESat and ICESat-2 laser altimeters, scientists precisely measured how much ice has been lost from ice sheets in Antarctica and Greenland between 2003 and 2019.
The Antarctic Peninsula, seen here, was one of the fastest changing regions of the continent.
Credits: NASA / K. Ramsayer
Credits: NASA / K. Ramsayer
Using their elevation data, the researchers found that Greenland is losing about 200 billion tons of mass each year on average.
That’s enough to raise sea levels by about eight millimeters, or a third of an inch, over the study period.
The mass loss figure is roughly similar to other recent estimates.
The study is the first to be published using data from ICESat-2, which was designed to have an operating life of at least three years.
Many more studies are expected that should add to the understanding of Earth’s frozen expanses.
“Where we’re at in ice sheet science is, there are still a lot of unknowns,” Dr. Gardner said.
One advantage of ICESat-2, he said, is its ability to measure changes in some of the smallest ice sheet features.
That will help scientists better understand how the changes are occurring and improve forecasts of future impacts as the climate continues to shift.
ICESat-2, he said, “reveals the process of change, and without understanding those processes you have no ability to make predictions.”
“It really just gives us this incredibly crisp, unified picture.”
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Thursday, June 18, 2020
Quantum entanglement could take GPS to the next level
University of Arizona engineers have
demonstrated how quantum capabilities could improve functions like GPS,
medical imaging, astronomy observation and more.
From Futurity by
Quantum entanglement can help detect radio frequencies with more sensitivity and accuracy than ever, researchers report.
Your phone’s GPS, the WiFi in your house, and communications on aircraft are all powered by radio-frequency waves, or RF waves, which carry information from a transmitter at one point to a sensor at another.
The sensors interpret this information in different ways.
For example, a GPS sensor determines its location by using the amount of time it takes to receive a signal from a satellite.
For applications such as in-door localization and defeating spoofing GPS signals, a wireless sensor measures the angle at which it receives an RF wave.
The more precisely the sensor can measure this time delay or angle of arrival, the more it can accurately determine location or enhance security.
In a paper in Physical Review Letters, researchers demonstrate how a combination of two techniques—radio frequency photonics sensing and quantum metrology—can give sensor networks a previously unheard-of level of precision.
The research involves transferring information from electrons to photons, then using quantum entanglement to increase the photons’ sensing capabilities.
“This quantum sensing paradigm could create opportunities to improve GPS systems, astronomy laboratories, and biomedical imaging capabilities,” says Zheshen Zhang, an assistant professor of materials science and engineering and optical sciences, as well principal investigator of the Quantum Information and Materials Group at the University of Arizona.
“It could be used to improve the performance of any application that requires a network of sensors.”
From electrons to light
Traditional antenna sensors transform information from RF signals to an electrical current made up of moving electrons.
However, optical sensing, which uses photons, or units of light, to carry information, is much more efficient.
Not only can photons hold more data than electrons, giving the signal larger bandwidth, but photonics-based sensing can transmit that signal much farther than electronics-based sensing, and with less interference.
Because optical signals offer so many advantages, the researchers used an electro-optical transducer to convert RF waves into the optical domain in a method called RF-photonics sensing.
“We designed a bridge between an optical system and a physical quantity in a completely different domain,” Zhang explains.
“We demonstrated that with an RF domain in this experiment, but the idea could also be applied to other scenarios.
For example, if you want to measure temperature using photons, you could use a thermo-optical transducer to convert the temperature into an optical property.”
A graphic demonstrating the team's quantum metrology experiment.
Breaking down quantum entanglement
After converting information to the optical domain, the researchers applied a technique called quantum metrology.
Usually, a sensor’s precision is limited by something called the standard quantum limit.
For example, smartphone GPS systems are usually accurate within a 16-foot radius.
Quantum metrology uses entangled particles to break past the standard quantum limit and take ultrasensitive measurements.
How does it work?
Entangled particles are tied together so anything that happens to one particle affects the particles it’s entangled with as well, as long as appropriate measurements are taken.
Picture a supervisor and an employee working together on a project.
Because it takes time for the employee to share information with his supervisor through methods like emails and meetings, the efficiency of their partnership is limited.
But if the two could entangle their brains together, the employee and the supervisor would automatically have the same information—saving time and allowing them to jointly tackle a common problem more efficiently.
Quantum metrology has been used to improve sensor precision in places like the Laser Interferometer Gravitational-Wave Observatory, or LIGO, which has opened up a new window for astronomers.
However, almost all prior quantum metrology demonstrations, including LIGO, only involve a single sensor.
Networks of sensors
However, RF waves are usually received by a network of sensors, each of which processes information individually—more like a group of independent employees working with their supervisors.
Quntao Zhuang, an assistant professor of electrical and computer engineering, previously demonstrated a theoretical framework to boost performance by teaming up entangled sensors.
This new experiment demonstrates for the first time that researchers can entangle a network of three sensors with one another, meaning they all receive the information from probes and correlate it with one another simultaneously.
It’s more like if a group of employees could share information instantly with their bosses, and the bosses could instantly share that information with each other, making their workflow ultra-efficient.
“Typically, in a complex system—for example, a wireless communications network or even our cellphones—there’s not just a single sensor, but a set of sensors that work together to undertake a task,” Zhang says.
“We’ve developed a technology to entangle these sensors, rather than having them operate individually.
They can use their entanglement to ‘talk’ to each other during the sensing period, which can significantly improve sensing performance.”
While the experiment only used three sensors, it opens the door to the possibility of applying the technique to networks of hundreds of sensors
“Imagine, for example, a network for biological sensing: You can entangle these biosensors so that they work together to identify the species of a biological molecule, or to detect neural activities more precisely than a classical sensor array,” Zhang says.
“Really, this technique could be applied to any application that requires an array or network of sensors.”
In theory work published in Physical Review X in 2019, Zhuang presented how machine learning techniques can train sensors in a large-scale entangled sensor network like this one to take ultra-precise measurements.
“Entanglement allows sensors to more precisely extract features from the parameters being sensed, allowing for better performance in machine learning tasks such as sensor data classification and principal component analysis,” Zhuang says.
“Our previous work provides a theoretical design of an entanglement-enhanced machine learning system that outperforms classical systems.”
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