Saturday, December 1, 2018

The Great Barrier Reef - Australia's ocean wonder from a new perspective

A visualisation of the Great Barrier Reef based on a joint project between Geoscience Australia, James Cook University and the Australian Hydrographic Service.
The visualisation shows the Great Barrier Reef sea floor in unprecedented detail.
The bathymetry dataset is produced at 30 metre resolution using a combination of historical and new sea floor mapping data and is a vast improvement on the previously available 250 metre resolution dataset.
The new dataset covers an area of 1.7 million square kilometres and provides a unique understanding of the structure of the Reef.

Friday, November 30, 2018

Global ocean circulation keeps slowing down: here's what it means

Global ocean circulation appears to be slowing
The Atlantic meridional overturning circulation (AMOC) is a key component of the global climate system. Recent studies suggested a twentieth‐century weakening of the AMOC of unprecedented amplitude (~15%) over the last millennium. 
NASA

 From Forbes by Trevor Nace

Scientists are keenly aware that global ocean circulation continues to slow down and warning signs are beginning to point to what the world will look like in the decades to come.

Researchers at the Swire Institute of Marine Science and the University of Hong Kong studied sediment and fossils off the coast of Canada to reconstruct ocean circulation in the past and where it is today.

The team, which published its findings in Geophysical Research Letters, found a dramatic weakening of ocean circulation during the last century.

The weakening of ocean circulation, specifically the Atlantic Meridional Overturning Circulation (AMOC), causes concern for North America and Europe into the future.
To understand what we can expect into the future, researchers look to the past for analogs.

Schematic of the circulation in the western North Atlantic
during episode of strong (left) and weak (right)
Geophysical Research Letters

A Look At The Past To Understand The Future


In the past, scientists have noted dramatic events called Heinrich events.
A Heinrich event is the sudden and large-scale breakup and subsequent melting of glaciers over the North Atlantic.
These events are thought to be associated with many ice age events, occurring in 5 of the past 7 ice ages here on Earth dating back 640,000 years.

Scientists believe we could be in a similar scenario today, where the breakup and melting of icebergs and glaciers in the North Atlantic and Greenland could cause a large freshwater input into the North Atlantic.
This sudden input of freshwater causes a cap to the global ocean circulation AMOC.

The key engine for the continued flow of AMOC is the sinking of cold and salty water in the North Atlantic.
As salty water moves northward from the tropics it cools off and becomes relatively more dense than the surrounding water.
This cold and salty water sinks to the bottom of the North Atlantic and begins to flow southward again along the ocean bottom.
This causes more salty water from the tropics to flow northward and the cycle continues.
This thermohaline circulation is what scientists fear is slowing down due to the fresh water cap from melting icebergs in the North Atlantic.


Ocean Circulation Plays an Important Role in Absorbing Carbon from the Atmosphere
The oceans play a significant role in absorbing greenhouse gases, like carbon dioxide, and heat from the atmosphere.
This absorption can help mitigate the early effects of human-emissions of carbon dioxide.
The Atlantic Meridional Overturning Circulation (AMOC) acts as a conveyor belt of ocean water from Florida to Greenland.
Along the journey north, water near the surface absorbs greenhouse gases, which sink down as the water cools near Greenland.
In this way, the ocean effectively buries the gases deep below the surface.
Credit: NASA's Goddard Space Flight Center/ Kathryn Mersmann

How Will A Slowing Ocean Circulation Impact Me?

As AMOC slows, it can have dramatic consequences for the climate and weather of especially North America and Europe. AMOC works to transfer vast amounts of ocean heat from the tropics to the northern latitudes.
Without this conveyor belt of warm water to the north, northern North America and Europe will experience colder conditions.

AMOC regulates global climate and works to distribute heat more evenly across the globe.
Without this mechanism in place, seasonal rainfall and temperatures will be altered to align with the new ocean/atmosphere scenario.

Oceanic circulation in the North Atlantic transports huge amounts of water, heat, salt, carbon, and nutrients around the globe.
As such, changes in the strength of oceanic currents can yield profound changes in both North American and European climate, in addition to affecting the African and Indian summer monsoon rainfall.
In this study, we used geochemical evidence to highlight a slowdown in the North Atlantic Ocean circulation over the last century.
This change appears to be unique over the last 1,500 years and could be related to global warming and freshwater input from ice sheet melt.
Based on our data, we also suggest that the period often called “The Little Ice Age” was characterized by a slowdown, of less amplitude than the modern weakening, in the North Atlantic Ocean circulation.
Thus, our results contribute to ongoing investigations of the state of the circulation in the North Atlantic by providing a robust reconstruction of its variability over the last 1,500 years.

Researchers point to the most recent scenario which appears similar to what we're experiencing today, the Little Ice Age.
This period, lasting from around 1300 to 1850 AD marked bitter cold conditions in Europe, famine, drought, and widespread population decline.
While scientists are unsure the exact mechanism that brought on this cold period, a leading hypothesis is the melting of high latitude North Atlantic ice and subsequent slowdown of ocean circulation.

While modern technology can help cope with long-term climate fluctuations, the impacts on the economy and health will be inevitable.
As our global climate continues to change we can both look to history as a blueprint for what is to come and to climate models for what could lie around the corner.

Links : 

Thursday, November 29, 2018

NovaSAR: UK radar satellite returns first images

Sydney Harbour: The famous bridge and opera house captured at night
NovaSAR can take images day or night, even through thick clouds 
Credit SSTL

 Sydney harbour with the GeoGarage platform
(AHS nautical chart overlayed upon Google satellite imagery)

From BBC by Jonathan Amos

Sydney Harbour and the Egyptian pyramids feature in the debut images from the first all-UK radar spacecraft.

NovaSAR was developed jointly by Surrey Satellite Technology Limited of Guildford and Airbus in Portsmouth, and launched to orbit in September.

Its pictures are now being assessed for use in diverse applications, including crop analysis, flood and forestry mapping, and maritime surveillance.

 Artwork: NovaSAR is an S-band radar satellite with a number of modes for different applications
Synthetic Aperture Radar is a powerful tool for monitoring the Earth from space due to its ability to see through clouds and image the Earth night and day, and NovaSAR-1 is the world’s first commercial SAR satellite to be operated at a 10:30 equator crossing time, providing time diversity for radar observations by affording increased daylight imaging opportunities in addition to night acquisitions. 

NovaSAR has something of the look of a cheese-grater
credit : Airbus DS

The intention ultimately is to fly a constellation of NovaSAR-like sats. 

Such a network would enable repeat images of locations to be acquired more quickly - something that is important if changes detected in a scene require a rapid response.
Reacting to an oil spill at sea would be a good example.

Portsmouth viewed by the NovaSAR radar instrument when it was flown on an aeroplane
credit : Airbus DS / SSTL

Satellite radar's great advantage is that it sees the Earth's surface in all weathers and at night.
Many other types of Earth observation (EO) spacecraft need daylight and cloud-free skies to gather their data.

NovaSAR-1 S-Band Radar 20km x 87 km image of Sydney taken at night at 6 metre resolution. Image size compressed from original file.
Credit SSTL

The picture of Sydney Harbour, with its famous bridge and opera house, illustrates this point: it was taken after dark.
The image is resolving objects that are six metres across and larger.
"What interests me most in this picture are the boats," said Luis Gomes, the chief technology officer at SSTL.
"NovaSAR is seeing not only large vessels but also much smaller pleasure craft. We can't see the shape of them, but we can certainly see that they are there. And that's encouraging because one of the main objectives of NovSAR will be maritime surveillance," he told BBC News.

NovaSAR-1 S-Band Radar image of Church Point Harbour, near Sydney, taken at night at 6 metre resolution.
The original image shows small boats moored in the natural harbour at Church Point, north of Sydney in a demonstration of the usefulness of SAR for detecting vessels of many different sizes and types, particularly at night or through cloud cover.  
Image zoomed and compressed from original file.
Credit SSTL

Church Point harbour with the GeoGarage platform
(AHS nautical chart overlayed upon Google satellite imagery)

The satellite is equipped with a receiver that can pick up Automatic Identification System (AIS) radio signals.
These are the positional transmissions that large ships are obliged to broadcast under international law.
Vessels that tamper with or disable these messages very often are engaged in smuggling or illegal fishing activity.
If such ships appear in NovaSAR's radar pictures, they will be reported to the authorities.

NovaSAR-1 S-Band Radar image of the Great Pyramids at Giza at 6 metre resolution.
Image zoomed and compressed from original file.
Credit SSTL.

NovaSAR-1 S-Band Radar image of the Red and Bent Pyramids near Dahshur at 6 metre resolution.
Image zoomed and compressed from original file size.
Credit SSTL.

The Cairo scene, featuring the Great Pyramids, showcases the satellite's ability to discern different land uses.
The picture includes buildings, cultivated fields, trees, and desert/rock.

NovaSAR-1 S-Band Radar 20km x 87km image of Cairo at 6 metre resolution.
Image size compressed from original file.
Credit SSTL

Martin Cohen, a radar expert with Airbus, commented: "The first image from orbit is always a key moment for everyone involved in such a mission, and this is no exception. The quality of the imagery is a credit to the hard work and dedication of the whole team here in Portsmouth.
"We look forward now to supporting SSTL through the rest of the commissioning phase, and seeing the mission begin full operational use."

There are a range of partners involved in assessing NovaSAR's capabilities.
These include EO specialists in India and Australia.
The UK's Ministry of Defence also wants to see what the spacecraft can offer Britain's armed forces.

 SSTL Spacecraft Operations Centre

UK engineers have long worked in space radar but their technology has previously always gone on broader missions, such as those for the European Space Agency.
NovaSAR, in contrast, is solely a British initiative.
The UK government has invested £21m in the project.
Science Minister Sam Gyimah said: "Yet again we can see UK research and innovation that is truly out of this world," he said.
"This 'eye in the sky' can capture an image a dozen times wider than the Strait of Dover and the data it provides can help crack problems from illegal shipping to alerting us to damaging pollution that needs to be countered."

Links :

Wednesday, November 28, 2018

The reality of autonomous shipping: striking the balance between captains and computers


From ABB

ABB Marine & Ports’ Eero Lehtovaara and Lloyd’s Register’s Jonathan Earthy weigh in on the visions and reality of ships sailing themselves.

When people start to get carried away on the subject of autonomous shipping, Eero Lehtovaara, Head of Regulatory Affairs at ABB Marine & Ports, likes to bring the conversation back down to earth: an autonomous vessel is not necessary unmanned but an unmanned vessel is, by default, autonomous to a high degree.

One of Lehtovaara’s main areas of focus is regulations governing responsibility for a ship, on board and on shore.
That places him squarely in the middle of the current discourse on unmanned ships.

Together with his ABB Marine & Ports colleague Dr. Kalevi Tervo, Lehtovaara recently published a white paper titled “B0 – a conditionally and periodically unmanned bridge” where “B0” stands for “Bridge zero”.
The “bridge zero” concept is decidedly not about unmanned shipping, but rather using digital and connected technology to enhance crew performance and optimize the human presence on board.

“B0 is the first realistic way of designing a partly autonomous vessel,” Lehtovaara says.
“The publicity generated by the unmanned or autonomous discussion is good for drawing attention to the subject, but truly unmanned shipping is not within realistic range right now, and may never be.
That being said, there are varying degrees of autonomy, and some can be explored and implemented today.”

The degrees he refers to can be divided into three basic and distinct categories:
Pier to pier, including docking, the most demanding of the three.
Pilot to pilot, meaning the part (or parts) of the voyage in between when the pilot has command.
Open or deep-water transport, the least complex level of automated operations.

“We recognize all three, but we have to start simple and move up the scale,” Lehtovaara says.
“In open water, the crew could manage their working hours in a different way than today if they were not obliged to stand watch on the bridge.
They could avoid boredom and fatigue, and at the same time tend to other practical tasks, while autonomous systems keep the ship on course and watch for potential danger.”

Jonathan Earthy, Human Factors Coordinator with the marine classification society Lloyd’s Register, echoes Lehtovaara’s arguments: “Automation is about empowering people with technology, not replacing them.”

All use of advanced technology, Earthy observes, must be preceded by consideration of how people are going to use it.
“Technology never does everything, or at least not as well as anticipated.
You can’t assume reliability, and it will take time to resolve issues related to autonomy, particularly regarding safety.” For now, he says, not all the necessary parameters are in place.
Not least, he reminds: “Ships are still designed to have humans on board.”

And that is not necessarily a bad thing.
“In general, humans make things safer at sea.
Ninety-eight percent of the time human problem-solving is successful,” Earthy says.
He argues that technology, employed optimally, will enhance and augment human capabilities: “Good human-machine parings give a good return on investment by making humans better, not by removing them.”

 Autonomous cargo ships in development at Rolls-Royce would be equipped with on-board satellite guidance and decision support.
Photo illustration courtesy of Rolls-Royce.

Lehtovaara emphasizes that such practical solutions are also within reach.
“The classification societies are currently reviewing the technology and the principles, and they are of the opinion that B0 is doable now, but still requires testing.
Once B0 is operational, our knowledge of unmanned operations will increase exponentially, moving us closer to the next step.
By not removing the captain from a ship, the periodically unmanned bridge concept allows us to advance our learning without having to resolve the biggest issue first.”

Not only would many dilemmas associated with automated ship operations be resolved by keeping crew on board, but also there is no strong economic incentive to remove them.
Lehtovaara points out that crew cost is around two percent of total operating costs on large merchant vessels, and as such is not the main driver for the development of unmanned shipping.
“There are stronger incentives for digitally enhanced operations than crew cost.
If for example machine-assisted viewing gains acceptance, requirements for line-of-sight from the bridge could be relaxed, and container ships could take more containers.
This would provide a direct and immediate business case.”


Taking a look back, Earthy reflects on the lofty nature of the current autonomous discussion.
“If you look at maritime technology predictions from five or six years ago, autonomy is barely mentioned.
Now a relatively small initiative has everyone emptying their pockets.”

The good thing, he assures, is that the autonomous discussion has raised technology on the agenda in a conservative industry.
“Now we need to focus on how to fit it all together.
Understanding all the tasks that need to be performed on a ship is the first step toward learning how to do them better.”

Links :