Bahamas WLP update in the GeoGarage platform

Bahamas WLP update

6 nautical raster charts added & 108 charts updated

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NASA finds new way to track ocean currents from space

 When we feel The Earth beneath our feet, see it with our eyes, hear it when the wind blows, we perceive only the most obvious filaments of a far more complex place.

Only with exquisite machines--spacecraft in orbit and powerful computers on the ground--can humanity begin to uncover the elegant nature of our complex home.
Presented here are a collection of data visualizations based on observations gathered by a fleet of spacecraft. In various depictions we see the currents of the world's oceans, changes in temperature and land cover over time, and precipitation as it cycles energy and water around our living planet.

From NASA

A team of NASA and university scientists has developed a new way to use satellite measurements to track changes in Atlantic Ocean currents, which are a driving force in global climate.
The finding opens a path to better monitoring and understanding of how ocean circulation is changing and what the changes may mean for future climate.

In the Atlantic, currents at the ocean surface, such as the Gulf Stream, carry sun-warmed water from the tropics northeastward.
As the water moves through colder regions, it sheds its heat.
By the time it gets to Greenland, it's so cold and dense that it sinks a couple of miles down into the ocean depths.
There it turns and flows back south.
This open loop of shallow and deep currents is known to oceanographers as the Atlantic Meridional Overturning Circulation (AMOC) -- part of the "conveyor belt" of ocean currents circulating water, heat and nutrients around the globe and affecting climate.

A schematic of the Atlantic meridional overturning circulation, otherwise referred to as the 'thermo-haline circulation', incorporating the Gulf Stream.

Because the AMOC moves so much heat, any change in it is likely to be an important indicator of how our planet is responding to warming caused by increasing greenhouse gases.
In the last decade, a few isolated measurements have suggested that the AMOC is slowing down and moving less water.
Many researchers are expecting the current to weaken as a consequence of global warming, but natural variations may also be involved.
To better understand what is going on, scientists would like to have consistent observations over time that cover the entire Atlantic.

"This [new] satellite approach allows us to improve projections of future changes and -- quite literally -- get to the bottom of what drives ocean current changes," said Felix Landerer of NASA's Jet Propulsion Laboratory, Pasadena, California, who led the research team.

Landerer and his colleagues used data from the twin satellites of NASA’s Gravity Recovery and Climate Experiment (GRACE) mission.
Launched in 2002, GRACE provides a monthly record of tiny changes in Earth's gravitational field, caused by changes in the amount of mass below the satellites.
The mass of Earth's land surfaces doesn't change much over the course of a month; but the mass of water on or near Earth's surface does, for example, as ice sheets melt and water is pumped from underground aquifers. GRACE has proven invaluable in tracking these changes.

 NASA's GRACE satellites (artist's concept) measured Atlantic Ocean bottom pressure as an indicator of deep ocean current speed.

In 2009, this pattern of above-average (blue) and below-average (red) seafloor pressure revealed a temporary slowing of the deep currents.

Credits: NASA/JPL-Caltech

At the bottom of the atmosphere -- on Earth's surface -- changes in air pressure (a measure of the mass of the air) tell us about flowing air, or wind.
At the bottom of the ocean, changes in pressure tell us about flowing water, or currents.
Landerer and his team developed a way to isolate in the GRACE gravity data the signal of tiny pressure differences at the ocean bottom that are caused by changes in the deep ocean currents.

“We've wanted to observe this phenomenon with GRACE since we launched 13 years ago, but it took us this long to figure out how to squeeze the information out of the data stream,” said Michael Watkins, director of the Center for Space Research at the University of Texas at Austin, former GRACE project scientist and a co-author of the study.

The squeezing process required some very advanced data processing, but not as many data points as one might think.
"In principle, you'd think you'd have to measure every 10 yards or so across the ocean to know the whole flow," Landerer explained.
"But in fact, if you can measure the farthest eastern and western points very accurately, that's all you need to know how much water is flowing north and south in the entire Atlantic at that section. That theory has long been known and is exploited in buoy networks, but this is the first time we've been able to do it successfully from space."

 The North Atlantic overturning circulation

with the location of the RAPID array moorings along 26°N.

The new measurements agreed well with estimates from a network of ocean buoys that span the Atlantic Ocean near 26 degrees north latitude.
The agreement gives the researchers confidence that the technique can be expanded to provide estimates throughout the Atlantic.
In fact, the GRACE measurements showed that a significant weakening in the overturning circulation, which the buoys recorded in the winter of 2009-10, extended several thousand miles north and south of the buoys' latitude.

The ocean buoy network, known as RAPID, is operated by the Rapid Climate Change group at the U.K.'s National Oceanography Centre, Southampton, together with the University of Miami and the Atlantic Oceanographic and Meteorological Laboratory of the National Oceanic and Atmospheric Administration.

Gerard McCarthy, a research scientist in the RAPID group who was not involved with the study, said, "The results highlight synergies between [direct measurements] like [those from] RAPID and remote sensing -- all the more important given the rapid and surprising changes occurring in the North Atlantic at the present time."
Eric Lindstrom, NASA’s Physical Oceanography Program manager at the agency's headquarters in Washington, pointed out, "It’s awesome that GRACE can see variations of deep water transport, [but] this signal might never have been detected or verified without the RAPID array. We will continue to need both in situ and space-based systems to monitor the subtle but significant variations of the ocean circulation."

A paper in the journal Geophysical Research Letters describing the new technique and first results is available online in prepublication form.

Links :

• NOC : Is the AMOC amok? 
• WP : NASA found a way to track ocean currents from space. What they saw is troubling
• GeoGarage blog :Why some scientists are worried about a surprisingly cold ‘blob’ in the North Atlantic Ocean 

Planning information on a single chart to help simplify port entry and exit

The UKHO's Port Approach Guides are port-scale charts that contain a wide range of planning and support information for some of the world's busiest ports.

By allowing bridge crews to view this information in one place, each guide can help to simplify a number of passage planning tasks; making port entry and exit quicker and easier.

From UKHO

Port Approach Guides offer:

• Information from a range of official ADMIRALTY charts and publications on one chart, helping bridge crews to plan for particular approaches and to support Master Pilot Exchange
• Quick Response (QR) codes, providing easy access to current warnings and notices for specific port areas. 
• Expanding coverage of some of the world's most complex approaches, including Antwerp, Rotterdam and the Panama Canal.

Extra information to aid planning
Each chart contains planning information such as contact details and harbour regulations, Vessel Traffic Service (VTS) information, principal lights and landmarks, specific warnings, tide and climate information, anchorages and prohibited areas, dangerous cargo, pilotage, berth information and port services.
By allowing you to view this information in one place, each guide can help to simplify a number of passage planning tasks.

Quick reference
ICS flags are used to link text panels to chart features, helping you to identify warnings and notices for specific ports and improve situational awareness.
QR codes also provide quick access to important information such as port authority websites, as well as online supporting applications such as ADMIRALTY EasyTide and Notice to Mariners WebSearch.

Familiarity and up-to-date information
All charts display widely used and instantly recognisable features and chart symbols, giving you clarity and reassurance during times of peak workload and pressure.
Any changes to port areas are also highlighted by regular updates via ADMIRALTY Preliminary Notice to Mariners (PNMs).
These PNMs, as well as 7 day tidal forecasts, can be accessed using QR Codes on each chart and are also available within our weekly paper NM bulletin.

Find out which Port Approach Guides are available by downloading our release schedule here.

Scientists confirm their fears about West Antarctica — that it’s inherently unstable

Simulation showing the major glaciers of the Amundsen Sea Embayment over three centuries of sustained retreat. The colours show the ice flow speed in metres per year.

The grounding line, which separates the grounded (resting on bedrock) ice from floating ice, is represented in bright blue.

Credit: Cornford et al., The Cryosphere, 2015

From Washington Post by Chris Mooney

It may be the biggest climate change story of the last two years.
In 2014, several research groups suggested that the oceanfront glaciers in the Amundsen Sea region of West Antarctica may have reached a point of “unstoppable” retreat due to warm ocean waters melting them from below. There’s a great deal at stake — West Antarctica is estimated to contain enough ice to raise global sea levels by 3.3 meters, or well over 10 feet, were it all to melt.
The urgency may now increase further in light of just published research suggesting that destabilization of the Amundsen sea’s glaciers would indeed undermine the entirety of West Antarctica, as has long been feared.

 The Thwaites glacier in western Antarctica. Photograph: AFP/Getty

In a new study published Monday in the Proceedings of the National Academy of Sciences, Johannes Feldmann and Anders Levermann of the Potsdam Institute for Climate Impact Research use a sophisticated climate model to study what will happen if these glaciers are, indeed, fully destabilized.And in essence, they find that the process of retreat doesn’t end with the region currently up against the ocean.
“We showed that there is actually nothing that stops it,” said Levermann.
“There are troughs and channels and all this stuff, there’s a lot of topography that actually has the potential to slow down or stop the instability, but it doesn’t.”
Or as the paper puts it: “The result of this study is an if–then statement, saying that if the Amundsen Sea Sector is destabilized, then the entire marine part of West Antarctica will be discharged into the ocean.”

The Potsdam Institute for Climate Impact Research
shows what would happen if glaciers in West Antarctica melted. 

West Antarctica can actually be considered the smallest of three planetary ice sheets — Greenland contains some 6 meters (20 feet) of potential sea level rise, and East Antarctica is the most vast of all, at nearly 60 meters, or 200 feet.

However, West Antarctica is currently believed to be the most vulnerable to rapid, large scale change, due to the fact that the Amundsen Sea’s glaciers are rooted on a seabed that slopes downward as you move further inland, in some places plunging a mile or more below sea level.
The region’s largest glacier, the gigantic Thwaites, is bigger than Pennsylvania and over a mile in total thickness in places — and may be the single most vulnerable point.

Indeed, Antarctic scientists have expressed a strong consensus that they need to conduct a lot more research in this very remote area as soon as possible, to determine how fast the change could happen.

 Antarctica is vital to the planet’s climate system.

The current study was not an example of — and cannot replace — this difficult fieldwork.
Rather, the researchers used a complex ice sheet model that simulated the entire West Antarctic ice sheet, as well as the Antarctic peninsula and some of East Antarctica.
They then simulated what they termed a 20 to 200 year “perturbation” to the region, in the form of increased rates of melt similar to what is believed may have already happened.
“Our modeled sea-level contribution from the perturbed region lies well within the range of observations,” they say.

With a 60 year or greater perturbation, the model — which, the researchers caution, is only “a single realization of an ice-sheet model that applies approximations to the ice dynamics” — then produced a retreat that continues even without continuance of the perturbation.
That is, after all, precisely what has been feared — that the region has an inherent “marine ice sheet instability,” as researchers put it.
“If you have a situation where the bedrock is declining when you go inland, that means that wherever the grounding line is, it is thicker the further it is inland,” explains Levermann.
“Which means the [ice] flux is bigger the further you go inland. Which means you lose more ice the further you go inland, which is the vicious cycle.”
Levermann confirmed, by email, that this in effect means that there is an “inherent” instability to West Antarctica, based on his new research.

Here’s a visualization of what is happening with West Antarctica, and how a “marine ice sheet instability” works:

The critical issue here is, of course, the speed at which this could all occur.
The new study’s simulations show the loss of West Antarctica playing out over thousands of years. But many scientists worry that at least some of the change could happen faster.

“We know very little about the new world we are entering of rapid retreat into deep basins,” said Sridhar Anandakrishnan, a glaciologist at Penn State University who has conducted research atop Thwaites glacier and reviewed the study for the Post, by email.
“There are likely processes there that we haven’t fully accounted for. For example, as the grounding line shifts farther back, the ice front may start to fracture and fail — something we don’t see today because we don’t have any deep grounding lines to study and use as analogies.”
When asked how fast he thought all of this could unfold, Levermann underscores that we simply don’t know.
“And by we don’t know, I mean, we don’t know,” he says.
“I don’t want to say it’s quicker, but it’s much more likely that it’s faster than these thousands of years, than [that] it’s slower.”
He points out that based on reconstructions of the planet’s past, there are reasons to think sea levels can rise fairly rapidly.

The study therefore concludes that:

The currently observed retreat in West Antarctica hence might mark the beginning of a millennial period of self-sustained ice discharge from West Antarctica and require long-term global adaptation of coastal protection, such as the building or rebuilding or raising of dykes, the construction of seawalls, or the realization of land fills in the hinterland.

Given the significance of the findings, the Post asked several other Antarctic experts to comment on the work.
Anandakrishnan, who was concerned that sea level rise could happen even faster than in the study, nonetheless  called the work a “fascinating study that shows the tipping points in the stability of the whole West Antarctic Ice Sheet (not just Thwaites or Pine Island, as some previous studies have shown)” by email.
“The retreat of Thwaites continues past any ‘local’ ups and downs in its bed, and affects the glaciers that flow into the Ross Ice Shelf and into the Filchner Ronne Ice Shelf.”
(You can see these regions on the map above.)

 Antarctic sea ice likely reached its annual maximum extent on Oct. 6, barring a late season surge. This video from NASA shows the evolution of the sea ice cover of the Southern Ocean from its minimum yearly extent to its peak extent.
see NASA

Jonathan Bamber, a glaciologist at the University of Bristol in the UK, also praised the study, calling the model “sophisticated” and adding, “It make take millennia for a full collapse but once it’s started we’re fully committed to multiple metres of sea level rise. How quickly we reach this point of no return, and how rapidly it proceeds, are sensitive to certain model details but what is clear is that the next few decades will determine whether the WAIS is just endangered or on its path to extinction.”

What’s striking is that even though we are now having this discussion about possible destabilization of West Antarctica, scientists are still not fully sure about what has caused the phenomenon.
One suspicion, however, is that the warming of the climate as a whole has changed wind patterns around Antarctica which, in turn, has also changed ocean patterns — allowing warmer water to reach the bases of mostly submerged glaciers that hold back the gigantic volumes of inland ice.

There is some concern that similar processes may also play out in submarine based glaciers of East Antarctica — although so far, scientists have not identified a part of the Antarctic continent that is both as vulnerable, and also experiencing as rapid change, as West Antarctica.
Despite all of this, Levermann cautions that the results should not be over-interpreted in an alarmist way, since whatever change may be occurring, it is certainly not expected to happen all at once.
“No one has to be afraid of sea level rise,” he says.
“One should be worried about sea level rise. It is not a threat to people, it’s a threat to things, and land, and cultural heritage.”

Links : 

• WP :  Scientists confirm that East Antarctica’s biggest glacier is melting from below /  Scientists declare an ‘urgent’ mission — study West Antarctica, and fast
• The Guardian : Melting ice in west Antarctica could raise seas by 3m, warns study  
• Nature : Antarctic coast meltdown could trigger ice-sheet collapse 
• The Conversation : Melting Antarctic ice sheets and sea level rise: a warning from the future 
• Popular Science : Parts Of Antarctica's Ice Sheet Seem To Be Growing. No, global warming Is not over
• Aljazeera : Experts dispute NASA study showing Antarctic ice gain
• GeoGarage blog : West Antarctic glacier loss appears unstoppable / Full map of Antarctic ice flow / Research casts alarming light on decline of West Antarctic glaciers / Warm ocean causing most Antarctic Ice shelf mass loss / Antarctica's scars hold clues to hidden water / Warming oceans could melt ice faster than expected / Antarctic ice shelves are melting dramatically, study finds / NASA: Antarctic sea ice grows – but the climate’s still changing 

In victory for Philippines, Hague Court to hear dispute over South China Sea

see interactive

From NYT by Jane Perlez

The Philippines has won an important ruling in its case against China over disputed parts of the South China Sea, with an arbitration court in the Netherlands saying it has jurisdiction in the case and will hold hearings.
The Permanent Court of Arbitration in The Hague issued the ruling on Thursday, in proceedings that China has boycotted since the Philippines, an ally of the United States, filed suit at the court in 2013.

The ruling was a blow to China, which had hoped the court would reject jurisdiction, allowing Beijing to continue making a case that its claims in the South China Sea are based on history rather than legal precedent.
The Philippines welcomed the decision on Friday and said it was prepared to argue the merits of its case before the tribunal.
“Our people can be assured that those representing our country have been continuously preparing for this,” said Abigail Valte, a spokeswoman for the Philippine president, Benigno S. Aquino III.
China’s Foreign Ministry said the country would not accept any ruling from the court, a standard statement from the ministry on the case.

It accused the Philippines of “a political provocation under the cloak of law.”

The case is being closely watched by the United States and other Asian nations that are claimants in the South China Sea, where China asserts sovereignty over islands and reefs within about 90 percent of the strategic waterway.

The Philippines — represented by an American lawyer, Paul Reichler, of the Washington law firm Foley Hoag — contends that it has the right to exploit oil and gas in waters in a 200-nautical-mile exclusive economic zone extending from territory that it claims in the South China Sea.
The Hague court rejected Beijing’s claims that the disputes in the sea are about its territorial sovereignty, which China says is based on historical rights and is indisputable.
Mr. Reichler made his arguments in July before the court, which was established in 1899 to encourage the peaceful resolution of international disputes.
There had been speculation about whether the court would accept the case, given China’s absence from the proceedings.

Who Claims What?
China claims sovereignty over all South China Sea islands and their adjacent waters and delineates its claims with a 'nine-dash' line, based on a map issued in 1947, but has never published coordinates for its precise location. China's claims overlap with those of Vietnam, Malaysia, Taiwan, Brunei and the Philippines.

Sources: Center for Strategic and International Studies (claim boundaries); U.S. Department of Defense (outposts)

courtesy of WSJ

The court ruled on Thursday that it had the authority to hear the Philippines’s submissions, which are based on the United Nations Convention on the Law of the Sea, a set of laws that the United States has not signed but uses as the basis of its policies in the heated contest with China over the South China Sea.

This week, an American destroyer, the Lassen, sailed within 12 nautical miles of Subi Reef, in the Spratly archipelago near the Philippines, which China has built into an artificial island.
A Chinese military airstrip is under construction on the island.
The American naval operation was devised to show that the new island does not have a 12-mile territorial zone.
The Law of the Sea says that bits of rock or reef that are elevated only at low tide are not entitled to such a zone.

In part of its case, the Philippines argues that China has prevented Philippine vessels from exploiting the waters adjacent to Scarborough Shoal and Johnson Reef, two small outcrops favored by fishermen.

In 2012, China put a barrier across the entrance to Scarborough Shoal that prevented Philippine fishing boats from entering its waters.
A deal brokered by the United States that called for both countries to withdraw from the shoal soon fell apart.

Assets in the Region
The size of China's maritime fleet far outnumbers the fleets of other countries in the region.

Sources: Office of Naval Intelligence; U.S. Department of Defense; regional naval officers; Congressional Research Service

Jay Batongbacal, the director of the Institute for Maritime Affairs and Law of the Sea at the University of the Philippines, said the ruling would be useful in diplomatic negotiations with other countries that oppose China’s actions in the South China Sea.
“The ruling could act to embolden and bring unity to the other claimants,” he said.

Zhu Feng, the executive director of the China Center for Collaborative Studies of the South China Sea at Nanjing University, said the ruling was not a defeat for China, adding, “The international jurisdiction will always move in its own way.”
But he said he supported the idea of China becoming more involved in the court proceedings.
“I hope Beijing could become more active in participating in all forums and respond to the international ruling at the tribunal,” he said.
 

Links :

• HuffingtonPost : Philippines vs. China: International Law or Rule of the Jungle? 
• TheDiplomat : A Legal Analysis of the Philippine-China Arbitration Ruling
• GeoGarage blog : Philippines uses 18th-century English aristocrat's map to claim disputed islands / US: China failed to clarify 9-dash line with law / Battle of the South China Sea charts / How China sees the South China Sea / Troubled waters: the South China Sea dispute / China's lawful position on the South China Sea / Piling sand in a disputed Sea, China literally gains ground