US NOAA update in the GeoGarage platform

4 nautical raster charts updated

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Guiding Charles Lindbergh over the Atlantic

Perhaps no event in the last 50 years, aside from man’s landing on the moon, has stirred the imaginations of people everywhere as much as the famous transatlantic flight of Captain Charles A. Lindbergh on the 20th of May 1927.
 Map image provided by the Missouri History Museum.
Graphic by Beth Neise, NGA Office of Corporate Communications

From Medium by Jessica Daues, NGA Office of Corporate Communications

Ninety years later, a look at an NGA predecessor organization’s contributions to the first solo transatlantic flight

Ninety years ago this May, Charles Lindbergh landed a single-engine monoplane, the Spirit of St. Louis, at Le Bourget airport northeast of Paris among more than 25,000 cheering spectators. Lindbergh emerged as the first pilot to complete a solo, transatlantic flight and the first pilot to fly nonstop from North America to mainland Europe.
Lindbergh’s flight made him an international sensation, popularized the concept of air travel and showed the world the potential of aviation.

And as Lindbergh landed in France, tucked away in his cockpit was the chart he used to navigate from New York to Paris — a chart made by the U.S. Hydrographic Office, an NGA predecessor agency.

Before Lindbergh’s transatlantic flight, the public perception of aviation was that of a risky, expensive novelty. Lindbergh, a former U.S. Army pilot, wanted his flight to Paris to change that.
“Businessmen think of aviation in terms of barnstorming, flying circuses, crashes and high costs per flying hour,” Lindbergh wrote in his book, The Spirit of St. Louis.
“Somehow they must be made to understand the possibilities of flight.”

Skeptics told Lindbergh that a solo trip across the Atlantic on a single-engine plane would be hazardous, if not suicidal.
Airplane companies dismissed the idea of an unknown airmail pilot from St. Louis achieving what no one had before.

But Lindbergh rallied support from the fledgling aviation community in St. Louis for his idea and raised money from local businessmen to purchase a plane custom-built for the trip, named the Spirit of St. Louis.
But could he find his way from New York to Paris?
Until his famous flight, Lindbergh had navigated only across land, not large bodies of water.
He had used landmarks on the ground — rivers, towns, lakes, railroad tracks — to help him determine where he was, Lindbergh wrote in his book.
To fly the Atlantic, Lindbergh decided he would have to navigate like a ship captain at sea.
To do that, he would need a set of charts that covered the Atlantic Ocean.

Lindbergh Chart of the Great circle sailing chart of the North Atlantic Ocean 1926

see UVW library 

 

 

source

  Graphic by Beth Neise, NGA Office of Corporate Communications

Lindbergh was in California at the time, with the engineers building his plane.
In a store in San Pedro, Lindbergh found exactly what he needed.
“The salesman pulls out two oblong sheets,” he wrote in The Spirit of St. Louis.
“They’re Mercator’s projections, and — yes, I’m in luck — they extend inland far enough to include New York and Paris.”
A Mercator’s projection is a map in which the meridians and the parallels of latitude are straight lines, intersecting each other at right angles.
Because of the spherical shape of the Earth, distortion increases as distance from the equator increases.
At least one, and likely both, of those charts were created by the Hydrographic Office.
“Then, like stumbling over a nugget of gold, I see a gnomonic projection covering them both [New York and Paris],” he wrote.

This gnomonic projection, also created by the Hydrographic Office, showed a projection of the Atlantic in which the eye is imagined to be at the center of the Earth sphere.
Lindbergh recalled his military training and knew he would need both charts to accurately navigate from New York to Paris.
“‘A great circle on the Earth’s surface translates into a curve on a Mercator’s chart, but it becomes a straight line on a gnomonic projection’ — I remember learning that in the Army’s navigation class,” he wrote.
“Why? Because all maps are distorted in one way or another. You can’t just skim the surface off a globe and flatten it out neatly on a table.”

Lindbergh Chart Time zone chart of the world 1927

see UWM Library

Lindbergh chart Variations of the compass for the year 1925 

 se UWM Library

Maps from the U.S. Hydrographic Office, an NGA predecessor organization, consulted by Charles Lindbergh during the planning of the first solo transatlantic flight.

Images courtesy of American Geographical Society Library, University of Wisconsin — Milwaukee Libraries

In addition to the gnomonic and Mercator projections of the Atlantic, Lindbergh also purchased a chart for magnetic variation and a time-zone chart, both also created by the Hydrographic Office, and some others showing the prevailing winds across the Atlantic during the spring.

An undated photo of the U.S. Hydrographic Office.

Image courtesy of NGA’s Historical Research Center.

The maps that would lead Lindbergh to Paris were part of the Hydrographic Office’s efforts to chart the harbors and coasts of the world for mariners.
The Hydrographic Office began in 1830 as the Depot for Charts and Instruments.
It was the first U.S. government entity to take responsibility for the mapping of oceans, lakes and rivers, or hydrographic charting.

 Pilot Chart of the North Atlantic Ocean.

June 1923 issue of the monthly aid to marine navigation published by the U.S. Hydrographic Office.

In 1842, the office began to implement an extensive system for collecting hydrographic information — ocean currents, winds, air pressure and temperature, water temperature and more — from mariners. It used this information to create accurate charts with exactly the information mariners most needed.
The program was so successful that the Hydrographic Office earned an international reputation for excellence in charting, wrote Mitchell Kalloch in A Concise History of the U.S. Hydrographic Office.

Lindbergh brought his Hydrographic Office charts back to the factory where his airplane was being built.
He settled into a drafting room and went to work.
“It’s a dusty, uninspiring place, with damp-spotted walls and [an] unshaded light bulb hanging down on a wire cord from the ceiling’s center,” he wrote.
“But there’s enough room to spread out sheets of charts and drawings.”

 from slides

In his book, Lindbergh described how he charted his course: On the gnomonic projection, he drew a straight line between New York and Paris.
Then he transferred points from that line, at 100-mile intervals, to the Mercator’s projection, and connected those points with straight lines to create a curved course, connecting the two cities.
At each point, Lindbergh marked the distance from New York and determined how to adjust his course to remain on his route and account for the magnetic variations he would find as he traveled across the Atlantic.

Lindbergh’s straight-line route on a gnomic projection became curved when translated to a Mercator projection.

Lindbergh cut out the relevant strips from his Mercator projections and used them to navigate to Paris.

Images courtesy of the Missouri History Museum.

Finished with his course, Lindbergh admired the arc he had created.
“It’s fascinating, that curving, polygonic line, cutting fearlessly over thousands of miles of continent and ocean,” Lindbergh wrote. “It curves gracefully northward through New England, Nova Scotia and Newfoundland, eastward over the Atlantic, down past the southern tip of Ireland, across a narrow strip of England, until at last it ends sharply at the little dot inside France marked ‘Paris’.”

Lindbergh decided to chart the route again using trigonometry, just to double-check his work.
After teaching himself the math from library books and spending several days performing calculations, Lindbergh was satisfied: His course was correct.

Map image courtesy of the Missouri History Museum. 
Graphic by Beth Neise, NGA Office of Corporate Communications

On May 20, 1927, at 7:52 a.m., Lindbergh took off from Roosevelt Air Field on Long Island, New York.
With him, he carried his arc, sketched on the Hydrographic Office Mercator’s projection between the continents.
A couple hours later, as he flew over Massachusetts and started over the Atlantic, he pulled out his route and checked his compass.
“This strip is my key to Europe,” he wrote in his book.
“With it, I can fly the ocean. … Without this strip, it would be as useless to look for Paris as to hunt for buried treasure without a pirate’s chart.”
After flying over Newfoundland, Lindbergh spent about 16 bleary hours over the Atlantic.
Then he spotted land on his horizon: the southwestern coast of Ireland!

At 10:22 p.m. French time, 33 ½ hours after taking off from New York, Lindbergh landed in Paris.
He had traveled 5,790 kilometers, nonstop, alone, in a little over a day, with a chart and a compass.

The significance of the successful flight was recognized immediately.
The exhausted Lindbergh emerged from his plane to face an effusive, nearly hysterical crowd.
He hadn’t slept for more than 63 hours.
“Twenty hands reached for him and lifted him out like he was a baby,” wrote Edwin James that day for The New York Times.
“He had strength enough, however, to smile and waved his hand to the crowd.”
Two French pilots quickly whisked Lindbergh away as the crowd surged.
Onlookers tore off pieces of his Spirit of St. Louis plane as souvenirs.
Newspaper reporters gathered at the U.S. Embassy, waiting for Lindbergh to arrive.

 A painting by former employee shows the Spirit of St. Louis flying close to the water on its trip across the Atlantic.

It was painted in the 1970s to decorate the agency’s Lindbergh dining room, which is now part of the Building 1 Conference Center at NGA’s St. Louis campus.

The painting currently hangs in NGA’s St. Louis museum.

Fortunately, among the chaos, Lindbergh’s Hydrographic Office charts survived.
Lindbergh donated the charts he used during the flight to the Missouri History Museum.
He donated the charts he used to plan the fight — the gnomonic, magnetic variation and time-zone maps — to the American Geographical Society, and they are now housed at the University of Wisconsin-Milwaukee Libraries.

The United States eventually folded the Hydrographic Department into the Defense Mapping Agency in 1972.
In 1978, the agency merged the Hydrographic Center with the Topographic Center, creating the Defense Mapping Agency Hydrographic/Topographic Center in Bethesda, Maryland.
In 1996, it became part of the National Imagery and Mapping Agency, which became NGA in 2003.
Despite the name changes, NGA employees continue the legacy of the Hydrographic Office even today.
NGA analysts, scientists and cartographers still deliver information that American airmen use to navigate safely.
NGA provides digital data used in navigation equipment in airplane cockpits and in mobile devices.

Map showing the overland and overseas flights of Charles A. Lindbergh, Colonel and flight comdr 110th observation Sqdn. Missouri Nat. Guard (1928)

courtesy of Univ. Hawaii

They also still create hard-copy paper maps, similar to the ones consulted by Lindbergh to achieve the transatlantic flight once thought impossible.
“I can hardly believe it’s true,” he wrote.
“I’m almost exactly on my route, closer than I hoped to come in my wildest dreams.”

Links :

• GeoGarage blog : Advisory NGA notice on "Web Mercator"
• Charles Lindbergh website 
• YouTube : F-0062 Charles Lindbergh flight video  / F 3086 Spirit of St. Louis Assembly Footage, Ryan Aeronautical Lindbergh in San Diego

Morocco sailing challenge

Hicham Aachi and Mehdi Rouizem launched a first sporting challenge:

to make a tour of Morocco to sail on a catamaran of sport without cabin!
They will leave in June 2017 from Saidia for a navigation along the Moroccan coast in 6 legs:
Saidia, Tangier, Mohammedia, Agadir, Laayoune and Dakhla.
That is a total of 1,300 nautical miles, which is around 2,400 km.
With this challenge, the two young sailors wish to start an awareness:
The Moroccan coast is full of richness and opportunities, and it deserves to be better preserved ...

Morocco coastal charts from SHOM on the GeoGarage platform

Cosmo : supremely relaxing fishing video

The Seychelles are an angler’s paradise – if you can actually get to them.
Follow the crew of the Alphonse Fishing Co. as they wade the flats of the Cosmoledo Atoll, hoping for a shot at Giant Trevally. 

see the story

Cosmoledo island with the GeoGarage platform

Terrifying 20m-tall 'rogue waves' are actually real

The Wave painting by Ivan Aivazovsky

From BBC by Nic Fleming

For centuries sailors told stories of enormous waves tens of metres tall.
They were dismissed as tall tales, but in fact they are alarmingly common

TEN-storey high, near-vertical walls of frothing water.
Smashed portholes and flooded cabins on the upper decks.
Thirty-metre behemoths that rise up from nowhere to throw ships about like corks, only to slip back beneath the depths moments later.
Evocative descriptions of abnormally large "rogue waves" that appear out of the blue have been shared among sailors for centuries.
With little or no hard evidence, and the size of the waves often growing with each telling, there is little surprise that scientists long dismissed them as tall tales.
Until around half a century ago, this scepticism chimed with the scientific evidence.
According to scientists' best understanding of how waves are generated, a 30m wave might be expected once every 30,000 years.

Rogue waves could safely be classified alongside mermaids and sea monsters.
However, we now know that they are no maritime myths.

A wave is a disturbance that moves energy between two points.
The most familiar waves occur in water, but there are plenty of other kinds, such as radio waves that travel invisibly through the air.
Although a wave rolling across the Atlantic is not the same as a radio wave, they both work according to the same principles, and the same equations can be used to describe them.
A rogue wave is one that is at least twice the "significant wave height", which refers to the average of the third highest waves in a given period of time.
According to satellite-based measurements, rogue waves do not only exist, they are relatively frequent.

The sceptics had got their sums wrong, and what was once folklore is now fact.
This led scientists to altogether more difficult questions.
Given that they exist, what causes rogue waves?
More importantly for people who work at sea, can they be predicted?
Until the 1990s, scientists' ideas about how waves form at sea were heavily influenced by the work of British mathematician and oceanographer Michael Selwyn Longuet-Higgins. In work published from the 1950s onwards, he stated that, when two or more waves collide, they can combine to create a larger wave through a process called "constructive interference".
According to the principle of "linear superposition", the height of the new wave should simply be the total of the heights of the original waves.

A rogue wave can only form if enough waves come together at the same point according to this view.
However, during the 1960s evidence emerged that things might not be so simple.
The key player was mathematician and physicist Thomas Brooke Benjamin, who studied the dynamics of waves in a long tank of shallow water at the University of Cambridge.
With his student Jim Feir, Benjamin noticed that while waves might start out with constant frequencies and wavelengths, they would change unexpectedly shortly after being generated.
Those with longer wavelengths were catching those with shorter ones.
This meant that a lot of the energy ended up being concentrated in large, short-lived waves.
At first Benjamin and Feir assumed there was a problem with their equipment.
However, the same thing happened when they repeated the experiments in a larger tank at the UK National Physical Laboratory near London.
What's more, other scientists got the same results.
For many years, most scientists believed that this "Benjamin-Feir instability" only occurred in laboratory-generated waves travelling in the same direction: a rather artificial situation.
However, this assumption became increasingly untenable in the face of real-life evidence.

At 3am on 12 December 1978, a German cargo ship called The München sent out a mayday message from the mid-Atlantic.

Despite extensive rescue efforts, she vanished never to be found, with the loss of 27 lives.
A lifeboat was recovered.
Despite having been stowed 66ft (20m) above the water line and showing no signs of having been purposefully lowered, the lifeboat seemed to have been hit by an extreme force.
However, what really turned the field upside down was a wave that crashed into the Draupner oil platform off the coast of Norway shortly after 3.20pm on New Year's Day 1995.
Hurricane winds were blowing and 39ft (12m) waves were hitting the rig, so the workers had been ordered indoors.
No-one saw the wave, but it was recorded by a laser-based rangefinder and measured 85ft (26m) from trough to peak.
The significant wave height was 35.4ft (10.8m).
According to existing assumptions, such a wave was possible only once every 10,000 years.
The Draupner giant brought with it a new chapter in the science of giant waves.

When scientists from the European Union's MAXWAVE project analysed 30,000 satellite images covering a three-week period during 2003, they found 10 waves around the globe had reached 25 metres or more.
"Satellite measurements have shown there are many more rogue waves in the oceans than linear theory predicts," says Amin Chabchoub of Aalto University in Finland.
"There must be another mechanism involved."
In the last 20 years or so, researchers like Chabchoub have sought to explain why rogue waves are so much more common than they ought to be.
Instead of being linear, as Longuet-Higgins had argued, they propose that rogue waves are an example of a non-linear system.
A non-linear equation is one in which a change in output is not proportional to the change in input.
If waves interact in a non-linear way, it might not be possible to calculate the height of a new wave by adding the originals together.
Instead, one wave in a group might grow rapidly at the expense of others.

When physicists want to study how microscopic systems like atoms behave over time, they often use a mathematical tool called the Schrödinger equation.
It turns out that certain non-linear version of the Schrödinger equation can be used to help explain rogue wave formation.
The basic idea is that, when waves become unstable, they can grow quickly by "stealing" energy from each other.
Researchers have shown that the non-linear Schrödinger equation can explain how statistical models of ocean waves can suddenly grow to extreme heights, through this focusing of energy.

In a 2016 study, Chabchoub applied the same models to more realistic, irregular sea-state data, and found rogue waves could still develop.
"We are now able to generate realistic rogue waves in the laboratory environment, in conditions which are similar to those in the oceans," says Chabchoub.
"Having the design criteria of offshore platforms and ships being based on linear theory is no good if a non-linear system can generate rogue waves they can't cope with."
Still, not everyone is convinced that Chabchoub has found the explanation.
"Chabchoub was examining isolated waves, without allowing for interference with other waves," says optical physicist Günter Steinmeyer of the Max Born Institute in Berlin.
"It's hard to see how such interference can be avoided in real-world oceans."
Instead, Steinmeyer and his colleague Simon Birkholz looked at real-world data from different types of rogue waves.

They looked at wave heights just before the 1995 rogue at the Draupner oil platform, as well as unusually bright flashes in laser beams shot into fibre optic cables, and laser beams that suddenly intensified as they exited a container of gas.
Their aim was to find out whether these rogue waves were at all predictable.
The pair divided their data into short segments of time, and looked for correlations between nearby segments.
In other words, they tried to predict what might happen in one period of time by looking at what happened in the periods immediately before.
They then compared the strengths of these correlations with those they obtained when they randomly shuffled the segments.

The results, which they published in 2015, came as a surprise to Steinmeyer and Birkholz.
It turned out, contrary to their expectations, that the three systems were not equally predictable.
They found oceanic rogue waves were predictable to some degree: the correlations were stronger in the real-life time sequence than in the shuffled ones.
There was also predictability in the anomalies observed in the laser beams in gas, but at a different level, and none in the fibre optic cables.
However, the predictability they found will be little comfort to ship captains who find themselves nervously eyeing the horizon as the winds pick up.
"In principle, it is possible to predict an ocean rogue wave, but our estimate of the reliable forecast time needed is some tens of seconds, perhaps a minute at most," says Steinmeyer.
"Given that two waves in a severe North Sea storm could be separated by 10 seconds, to those who say they can build a useful device collecting data from just one point on a ship or oil platform, I'd say it's already been invented.
It's called a window."
However, others believe we could foresee rogue waves a little further ahead.
The complexity of waves at sea is the result of the winds that create them.
While ocean waves are chaotic in origin, they often organise themselves into packs or groups that stay together.

In 2015 Themis Sapsis and Will Cousins of MIT in Cambridge, Massachusetts, used mathematical models to show how energy can be passed between waves within the same group, potentially leading to the formation of rogue waves.
The following year, they used data from ocean buoys and mathematical modelling to generate an algorithm capable of identifying wave groups likely to form rogues.
Most other attempts to predict rogue waves have attempted to model all the waves in a body of water and how they interact.
This is an extremely complex and slow process, requiring immense computational power.
Instead, Sapsis and Cousins found they could accurately predict the focusing of energy that can cause rogues, using only the measurements of the distance from the first to last waves in a group, and the height of the tallest wave in the pack.
"Instead of looking at individual waves and trying to solve their dynamics, we can use groups of waves and work out which ones will undergo instabilities," says Sapsis.
He thinks his approach could allow for much better predictions.
If the algorithm was combined with data from LIDAR scanning technology, Sapsis says, it could give ships and oil platforms 2-3 minutes of warning before a rogue wave formed.
Others believe the emphasis on waves' ability to catch other waves and steal their energy – which is technically called "modulation instability" – has been a red herring.

"These modulation instability mechanisms have only been tested in laboratory wave tanks in which you focus the energy in one direction," says Francesco Fedele of Georgia Tech in Atlanta.
"There is no such thing as a uni-directional stormy sea.
In real-life, oceans' energy can spread laterally in a broad range of directions."
In a 2016 study, Fedele and his colleagues argued that more straightforward linear explanations can account for rogue waves after all.
They used historic weather forecast data to simulate the spread of energy and ocean surface heights in the run up to the Draupner, Andrea and Killard rogue waves, which struck respectively in 1995, 2007 and 2014.
Their models matched the measurements, but only when they factored in the irregular shapes of ocean waves.
Because of the pull of gravity, real waves have rounded troughs and sharp peaks – unlike the perfectly smooth wave shapes used in many models.
Once this was factored in, interfering waves could gain an extra 15-20% in height, Fedele found.
"When you account for the lack of symmetry between crest and trough, and add it to constructive interference, there is an enhancement of the crest amplitudes that allows you to predict the occurrence observed in the ocean," says Fedele.
What's more, previous estimates of the chances of simple linear interference generating rogue waves only looked at single points in time and space, when in fact ships and oil rigs occupy large areas and are in the water for long periods.
This point was highlighted in a 2016 report from the US National Transportation Safety Board, written by a group overseen by Fedele, into the sinking of an American cargo ship, the SS El Faro, on 1 October 2015, in which 33 people died.
"If you account for the space-time effect properly, then the probability of encountering a rogue wave is larger," Fedele says.

Also in 2016, Steinmeyer proposed that linear interference can explain how often rogue waves are likely to form.
As an alternative approach to the problem, he developed a way to calculate the complexity of ocean surface dynamics at a given location, which he calls the "effective" number of waves.
"Predicting an individual rogue wave event might be hopeless or non-practical, because it requires too much data and computing power.
But what if we could do a forecast in the meteorological sense?" says Steinmeyer.
"Perhaps there are particular weather conditions that we can foresee that are more prone to rogue wave emergence."
Steinmeyer's group found that rogue waves are more likely when low pressure leads to converging winds; when waves heading in different directions cross each other; when the wind changes direction over a wide range; and when certain coastal shapes and subsea topographies push waves together.
They concluded that rogue waves could only occur when these and other factors combined to produce an effective number of waves of 10 or more.
Steinmeyer also downplays the idea that anything other than simple interference is required for rogue wave formation, and agrees that wave shape plays a role.
However, he disagrees with Fedele's view that sharp peaks can have a significant impact on wave height.
"Non-linearities have a role, but it's a minor one," he says.
"Their main role is that ocean waves are not perfect sine waves, but have more spikey crests and depressed troughs.
However, what we calculated for the Draupner wave is that the effect of non-linearities on wave height was in the order of a few tens of centimetres."

In fact, Steinmeyer thinks that Longuet-Higgins had it pretty much right 60 years ago, when he emphasised basic linear interference as the driver of large waves, rogue or otherwise.
But not everyone agrees.
In fact, the argument over exactly why rogue waves form seems set to rumble on for some time.
Part of the issue is that several kinds of scientists are studying them – experimentalists and theoreticians, specialists in optical waves and fluid dynamics – and they have not as yet done a good job of integrating their different approaches.
There is no sign that a consensus is developing.
But it is an important question to solve, because we will only be able to predict these deadly waves when we understand them.
For anyone sitting on an isolated oil rig or ship, watching the swell of the waves under a stormy sky, those few minutes of warning could prove crucial.

Links :

• Hakai magazine : Validating Tall Tales of Rogue Waves
• Rice Univ : Ultracold atom waves may shed light on rogue ocean killers 
• ScienceWorldReport : Explaining The Formation Of Rogue Waves And Tsunamis Based On Principles Of Quantum Physics; Using Atomic Waves To Understand Ocean Waves
• GeoGarage blog :NZ tech could reveal planet's largest waves / Study finds massive rogue waves aren't as rare as ... / How rogue waves are created in the ocean ... /