Tuesday, June 6, 2023

Spoofed AIS signals form symbol of Russian invasion

 Courtesy Geollect

From Maritime Executive

Geospatial intelligence firm Geollect has identified a spoofed AIS pattern tracing out the "Z" symbol of the Russian invasion of Ukraine at a position off the coast of Crimea.
It is the latest in a long string of spoofing incidents in the region, and the pattern has long been attributed to Russian government actors.

Remote GPS spoofing can trick a GPS receiving unit into calculating a false location.
Among other applications, this form of signal interference can be used to defeat the GPS guidance systems of certain U.S.- and NATO-made drones and precision weapons.
Russia is reportedly proficient in this form of electronic warfare.

There is a long history of GPS spoofing near Russian and Russian-occupied areas of the Black Sea coastline, and it periodically affects shipping.
Since a ship's AIS transponder broadcasts the location it receives from the ship's GPS unit, a broad-scale GPS spoofing attack will displace the "location" that the ship broadcasts via AIS, producing results that can sometimes appear bizarre.
In 2017, more than 20 ships reported that their GPS positions had been erroneously relocated 25 nm inland to the airport in Novorossiysk.
Others at anchor appeared "clustered" in areas where there were no radar returns for ships.

Over the course of 2017-19, non-profit analytics group C4ADS catalogued about 10,000 similar incidents affecting 1,300 vessels, most in or around areas of Russian influence.
The report also drew a correlation between the movements of Russian President Vladimir Putin and the mass spoofing events, noted contributor and cybersecurity expert Dana Goward.

In June and July 2021, three NATO warships - the Royal Navy's USS Defender, the U.S.
Navy's USS Ross and a Royal Dutch Navy vessel - all had their locations spoofed to positions off Russian-occupied Crimea.
The reason and culprit remain unknown.

This month, a large number of merchant ships along the southern coast of Ukraine had their AIS locations remotely spoofed to the coastal waters of Russian-occupied Crimea.
However, instead of a random pattern or a cluster, the AIS positions form a clear "Z" shape, the de facto symbol of support for the Russian invasion.
This AIS spoofing pattern was almost certainly created by transmitting false AIS signals, mimicking the ships' actual AIS transmissions with corrupted duplicates, according to Geollect.

"It is highly likely that this is a deliberate information operation by a pro-Russian actor (possibly Russian military psychological operations) ahead of an anticipated Ukrainian counteroffensive and/or in celebration of Russia's proclaimed victory over Bakhmut," assessed Geollect.

The pattern began to show up on AIS on the 14th, and strengthened from May 19-21.
Putin declared victory over Ukrainian forces in Bakhmut on May 22.
In a clear sign of spoofing, merchant vessel "speeds" between these erroneous AIS positions were as high as 100 knots, Geollect reported.
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Monday, June 5, 2023

Climate change: Norwegian seafloor holds clue to Antarctic melting

Image source, David Vaughan
There are lessons for Antarctica half a world away, on the floor of the Norwegian Sea

From BBC by Jonathan Amos

Antarctica's melting ice sheet could retreat much faster than previously thought, new research suggests.

The evidence comes from markings on the seafloor off Norway that record the pull-back of a melting European ice sheet thousands of years ago.

Today, the fastest withdrawing glaciers in Antarctica are seen to retreat by up to 30m a day.

But if they sped up, the extra melt water would have big implications for sea-level rises around the globe.

Ice losses from Antarctica caused by climate change have already pushed up the surface of the world's oceans by nearly 1cm since the 1990s.

The researchers found that with the Norwegian sheet, the maximum retreat was more than 600m a day.

"This is something we could see if we continue with the upper estimates for temperature rise," explained Dr Christine Batchelor from Newcastle University, UK.
"Although, worryingly, when we did the equations to think about what would be needed to instigate such retreat in Antarctica, we actually found there are places where you could get similar pulses of withdrawal even under the basal melt rates we know are happening at the moment," she told BBC News.

Dr Batchelor and colleagues report their research in this week's edition of the journal Nature.

The team has been looking at a great swathe of seafloor off the central Norwegian coast.
Twenty thousand years ago, this area was witness to a massive Northern European ice sheet in the process of withdrawal and break-up.

The sheet's past existence is written into more than 7,600 parallel, ladder-like ridges that have been sculpted in the seafloor's muddy sediments.
These corrugations are less than 2.5m high and are spaced between about 25m and 300m apart.
The scientists interpret the ridges to be features that are generated at an ice grounding zone.

This is the zone where glacier ice flowing off the land into the ocean becomes buoyant and starts to float.
The corrugations are created as the ice at this location repeatedly pats the sediments as the daily tides rise and fall.

For the pattern to have been produced and preserved, the ice must have been in retreat (advancing ice would destroy the ridges); and the tidal "clock" therefore gives a rate for this reversal.

Image source, COPERNICUS data/ESA
Satellites can map the retreat of Antarctic glaciers but their record is short - just 40 years or so

The team's results show the former European ice sheet underwent pulses of rapid retreat at speeds of 55m to 610m per day.

Importantly, the fastest rates were observed in places where the seafloor was relatively flat.
These are locations where the ice above would tend to be more uniform in thickness and where less melting is required to make the ice float to aid its retreat.

Similar corrugations have been detected on the seafloor around Antarcticabut the examples are quite limited in extent.
The Norwegian study area is vastly greater and so gives a much clearer impression of how quickly ice can go backwards in a warming climate.

Today, scientists use satellites to monitor the grounding zones of Antarctica's ocean-terminating glaciers.
The spacecraft can trace where the ice is being lifted and lowered on the tides.

The fastest retreat has been observed at Pope Glacier in the west of the continent, where an average rate of 33m a day was measured over a period of 3.5 months in 2017.

But Pope is not one of Antarctica's mightier glaciers. Scientists are more interested in behemoths such as Thwaites.
This body of ice is the size of Britain and could raise global sea levels by half a metre, were it all to melt.

"Four kilometres inland of the current grounding line at Thwaites, there is a conduit-like channel where the seabed is flat. It is the perfect setting for this process of buoyancy-driven retreat," said co-author Dr Frazer Christie of the Scott Polar Research Institute (SPRI), Cambridge University, UK.
"We're talking about a small area compared with Thwaites' entire drainage basin, but even a short-lived, very rapid retreat will have implications for the future dynamics of the glacier."

Drs Batchelor and Christie say their team's observations will fine-tune the computer models that try to forecast Antarctica's destiny in an ever-warming world.
At the moment, these models are missing important details of ice behaviour.
"But this is why we look into the geological past to tell us what's possible. Yes, we have satellites, but their records are very short - only 40 years or so," commented co-author Prof Julian Dowdeswell, also from SPRI.

"Importantly, the geological record is something that has actually happened. It's an 'observation' in the real world, not just in the computer model world," he told BBC News.
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Sunday, June 4, 2023

Deepest part of the oceans

Measuring the Greatest Ocean Depth
The Challenger Deep in the Mariana Trench is the deepest known point in Earth's oceans. In 2010 the United States Center for Coastal & Ocean Mapping measured the depth of the Challenger Deep at 10,994 meters (36,070 feet) below sea level with an estimated vertical accuracy of ± 40 meters.
If Mount Everest, the highest mountain on Earth, were placed at this location it would be covered by over one mile of water.
The first depth measurements in the Mariana Trench were made by the British survey ship HMS Challenger, which was used by the Royal Navy in 1875 to conduct research in the trench.
The greatest depth that they recorded at that time was 8,184 meters (26,850 feet).
In 1951, another Royal Navy vessel, also named the "HMS Challenger," returned to the area for additional measurements.
They discovered an even deeper location with a depth of 10,900 meters (35,760 feet) determined by echo sounding.
The Challenger Deep was named after the Royal Navy vessel that made these measurements.
In 2009, sonar mapping done by researchers aboard the RV Kilo Moana, operated by the University of Hawaii, determined the depth to be 10,971 meters (35,994 feet) with a potential error of ± 22 meters.
The most recent measurement, done in 2010, is the 10,994 meter ( ± 40 meter accuracy) depth reported at the top of this article, measured by the United States Center for Coastal & Ocean Mapping.

Saturday, June 3, 2023

Visualizing the human impact on the ocean economy

From VisualCapitalist by Iman Gosh   

When you think of economic output, it’s likely the ocean isn’t the first entity that comes to mind.
But from facilitating international trade to regulating the climate, the “blue economy” contributes significant value in both tangible and intangible ways.

The sustainable use of the ocean and its resources for economic development and livelihoods have such far-reaching effects, that its protection is a significant goal of the United Nations, as well as for many other countries and organizations throughout the world.

However, these vital ocean assets are in danger of sinking quickly.
We look at the total value of assets that come from our ocean, and how various human activities are affecting these resources.
Global Ocean Asset Value

Economic value from all the oceans is measured both by their direct output, as well as any indirect impacts they produce.

According to the World Wildlife Fund, these combined assets are valued at over $24 trillion.
Here’s how they break down:
  • Direct Output: Marine fisheries, coral reefs, seagrass, and mangroves
    • Total value: $6.9T
    • Examples of direct output: Fishing, agriculture
  • Trade and Transport: Shipping lanes
    • Total value: $5.2T
  • Adjacent Assets: Productive coastline, carbon absorption
    • Total value: $7.8T, and $4.3T respectively
    • Examples of services enabled: Tourism, education/conservation (such as jobs created)
In fact, the annual gross marine product of the oceans is comparable to the Gross Domestic Product (GDP) of countries, coming in at $2.5 trillion per year—making it the world’s eighth largest economy in country terms.

Unfortunately, experts warn that various human activities are endangering these ocean assets and their reliant ecosystems.
The Cumulative Human Impact on Oceans

An 11-year long scientific study tracked the global effect of multiple human activities across diverse marine environments.
The researchers identified four main categories of stressors between 2003-2013.
  • Climate change: Sea surface temperature, ocean acidification, and sea level rise
  • Ocean: Shipping
  • Land-based: Nutrient pollution, organic chemical pollution, direct human pollution, light pollution
  • Fishing: Commercial and artisanal fishing, including trawling methods
Across the board, climate stressors were the most dominant drivers of change in a majority of marine environments.
Similarly, pollution levels have also increased for many ecosystems.

Plastic pollution is especially damaging, as it continues to grow at u
nprecedented rates, with a significant amount ending up in the oceans.
The World Economic Forum estimates that by 2050, there could be more plastic in the ocean than fish by weight.

Among the various marine environments, coral reefs, seagrasses, and mangroves proved to be most at-risk, experiencing the fastest increase in cumulative human impact.
However, these are also the same ecosystems that we rely on for their direct economic output.

Overall, climate-induced declines in ocean health could cost the global economy $428 billion annually by 2050.
The Ocean Economy is in Hot Water

It can be difficult to truly understand the scale at which we rely on the ocean for climate regulation.
The ocean is a major “carbon sink”, absorbing nearly 30% of the carbon emitted by human activity.
But acidity levels and rising sea surface temperatures are changing its chemistry, and reducing its ability to dissolve CO₂.

According to the UN, ocean acidification has grown by 26% since pre-industrial times.
At our current rates, it could rise to 100-150% by the end of the century.
Overfishing is another urgent threat that shows no signs of slowing down, with sustainable fish stocks declining from 90% to 66.9% in just over 40 years.

To try and counteract these issues, this year’s virtual World Oceans Day is focused on “Innovation for a Sustainable Oceans” to discuss various solutions, including how the private sector can work with communities to maintain the blue economy.
In addition, there’s a petition in place to urge world leaders to help protect 30% of the natural world by 2030.

Will our human activities continue to stress the ocean economy, or will we be able to positively reverse these trends in the years to come?

Friday, June 2, 2023

Why don't hurricanes form at the equator?

An digitally enhanced satellite view of hurricane Dorian from 2019.
But why don't Dorian and other hurricanes form at the equator?
(Image credit: Roberto Machado Noa via Getty Images)

From LiveSciences by Charles Q. Choi

Here's why hurricanes, also known as tropical cyclones and typhoons, don't form at the equator and why it would be rare for them to cross it.(opens in new tab)

The fierce winds of a hurricane are known as tropical cyclones in some parts of the world, so you might expect them to sweep across the entire tropics.
But there's one area of the tropics where hurricanes almost never form: the equator.

Historical maps of the locations of tropical cyclones (also known as typhoons and hurricanes, depending on the location) would reveal that "it is extremely rare for them to form within a few degrees of the equator," Gary Barnes(opens in new tab), a meteorologist who's now retired from the University of Hawaii, told Live Science.
(One degree of latitude covers about 69 miles, or 111 kilometers.)

But why aren't there hurricanes at the equator?

This graphic shows the Coriolis effect, or how Earth's rotation influences the winds' direction north and south of the equator.
(Image credit: Shutterstock)
The reason is linked to why tropical cyclones rotate, which is due to Earth's spin.
At the equator, even when the air is calm, the planet and the atmosphere above it are actually moving at over 1,000 mph (1,600 km/h), Barnes said.
This movement follows Earth's direction of spin from west to east.

Earth's circumference is largest at the equator.
This means anything standing on the equator is moving faster eastward than anything lying away from the equator — anything on the equator is traveling a greater distance than anything north or south on Earth's surface in the same amount of time.

If air moves north from the equator, it will also still flow quickly eastward compared with its new surroundings.
This means air traveling north from the equator will appear to veer right.
In contrast, air flowing south from the equator will appear to stray left.

This phenomenon, known as the Coriolis effect, helps control the direction in which tropical cyclones spin.
In the Northern Hemisphere, rightward-turning air will create a counterclockwise spinning motion, and the opposite will occur in the Southern Hemisphere.

"Hurricanes collect rotation from the environment around them," Paul Roundy(opens in new tab), an atmospheric scientist at the University of Albany in New York, told Live Science.

This apparent turning of the wind "is very weak near the equator but becomes much stronger as latitude increases," Barnes said.
This is why tropical cyclones only rarely form near the equator — higher latitudes have faster-spinning winds to help drive tropical cyclone growth.

In December 2021, Tropical Cyclone Vamei occurred just 93 miles (150 kilometers) north of the equator, making it the closest hurricane to the equator since record keeping began.
(Image credit: Image courtesy NASA/JPL QuikSCAT science team)

Still, "there are odd exceptions," Barnes noted.
For instance, in 2001 the South China Sea, Tropical Cyclone Vamei "intensified within 2 degrees of the equator, but the nascent circulation actually formed earlier, farther away from the equator," he said.
Scientists think winds interacting with island terrain in the Indonesian archipelago may have generated the rotation that gave rise to Vamei, he said.

If a tropical cyclone were to cross the equator, "it would begin ingesting air rotating in the opposite direction," Roundy said.
Barnes noted that this would likely drive the storm to weaken and collapse.

However, "it's conceivable that a storm could cross the equator some small distance, since the opposing rotation remains fairly small close to the equator," Roundy said.
"It is probably not possible for a tropical cyclone to cross several degrees of latitude into the opposite hemisphere."

Climate change "does not significantly affect the rotation of the Earth, so it won't directly impact the chances of a hurricane crossing the equator," Roundy noted.
"However, if rare storms at low latitude were able to achieve higher intensities, if they happened to move toward the equatorial region, they might better maintain there.
Climate change might increase the strength of the strongest storms."

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