Saturday, December 22, 2012

Pointe du Raz

Pointe du Raz 22 novembre 2012 from Ronan Follic

 photo Ronan Follic

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Friday, December 21, 2012

Vendee Globe : crossing the antimeridian (the 180th degree meridian)

Situation 21/12/2012 19:00 UTC
The two leaders crossed the antimeridian : West meets East

>>> geolocalization with the Marine GeoGarage <<<<
Mercator projection presents the meridians by vertical straight lines

With info from V&V & wikipedia

Points with the same longitude lie in lines running from the North Pole to the South Pole.

By convention, one of these, the Prime Meridian, which passes through the Royal Observatory, Greenwich, England, establishes the position of zero degrees longitude.
The longitude of other places is measured as an angle east or west from the Prime Meridian, ranging from 0° at the Prime Meridian to +180° eastward and −180° westward.

The United Kingdom and its former colonies established the Royal Observatory at Greenwich just outside of downtown London in 1675.
This national observatory was established as the starting location for longitude or the y-axis for the British coordinate system.

Since the United Kingdom was a major colonial power and a major navigational power of the eighteenth and nineteenth centuries, their maps and navigational charts with the prime meridian passing through Greenwich were promulgated and many other countries adopted Greenwich as their prime meridians.
Britain had more shipping and ships using the Greenwich Meridian than the rest of the world put together (at the time) : the British Nautical Almanac started these charts in 1767.

By 1884, international travel was commonplace and the need for a standardized prime meridian became readily apparent.
Forty-one delegates from twenty-five "nations" met in Washington D.C. for a conference to establish zero degrees longitude and the prime meridian.

Greenwich was selected as the prime meridian by a vote of twenty-two in favor, one against (Haiti), and two abstentions (France and Brazil).
By the time of the conference, the United Kingdom and its colonies as well as the United States of America had already begun using Greenwich as the prime meridian; this weighed heavily on the selection process.

The 180th meridian or antimeridian is the meridian which is 180° east or west of the Prime Meridian with which it forms a great circle.
An Anti-Meridian is a meridian opposite any given meridian of longitude : so specifically the Anti-Meridian is the 180th meridian (tthe meridian opposite of the Prime Meridian)
It is common to both east longitude and west longitude.

Vendée Globe : how to navigate to East to hit the West

Longitude is given as an angular measurement ranging from 0° at the Prime Meridian to +180° eastward and −180° westward.
The Greek letter λ (lambda), is used to denote the location of a place on Earth east or west of the Prime Meridian.

With the establishment of the prime meridian and zero degrees longitude at Greenwich, the 1884 Washington International meridian conference also established time zones, following the concepts of Canadian railroad engineer Sir Sanford Fleming (report).
By establishing the prime meridian and zero degrees longitude in Greenwich, the world was then divided into 24 time zones (since the earth takes 24 hours to revolve on its axis) and thus each time zone was established every fifteen degrees of longitude, for a total of 360 degrees in a circle.
So, it is used as the basis for the International Date Line because it for the most part passes through the open waters of the Pacific Ocean.
However, the meridian passes through Russia and Fiji as well as Antarctica.

The International Date Line can cause confusion among especially airline travelers.
The most troublesome and odd situations usually occurs with short journeys from west to east.
To travel from Tonga to (American) Samoa by air, for example, takes approximately two hours but involves crossing the International Date Line, causing passengers to arrive the day before they left. This often causes confusion in travel schedules, like hotel bookings unless those schedules quote times in UTC, but they typically do not since they must match domestic travel times, local transport, or meeting times.
Because the agreed IDL do not follow the 180° longitude in the middle of the Pacific Ocean a kind of odd daily date situation occurs.
For 2 hours every day, between 10:00 and 11:59 UTC, there exist 3 different weekdays concurrently.
For example at UTC time Tuesday 10:15, it is Monday 23:15 in American Samoa, which is 11 hours behind UTC, and it is Wednesday 00:15 in Kiritimati, which is 14 hours ahead of UTC.
For the first hour (UTC 10:00–10:59), this is true for inhabited territories, whereas during the second hour (UTC 11:00–11:59) it is only true if you count the uninhabited maritime time zone 12 hours behind UTC. 

Longitude at a point may be determined by calculating the time difference between that at its location and Coordinated Universal Time (UTC).
Since there are 24 hours in a day and 360 degrees in a circle, the sun moves across the sky at a rate of 15 degrees per hour (360°/24 hours = 15° per hour).
So if the time zone a person is in is three hours ahead of UTC then that person is near 45° longitude (3 hours × 15° per hour = 45°).
The word near was used because the point might not be at the center of the time zone; also the time zones are defined politically, so their centers and boundaries often do not lie on meridians at multiples of 15°.
In order to perform this calculation, however, a person needs to have a chronometer (watch) set to UTC and needs to determine local time by solar or astronomical observation.
The details are more complex than described here: see the articles on Universal Time and on the equation of time for more details.

The International Date Line (IDL) is linked to the antimeridian.
The advantage of having the Prime meridian in Europe is to get an Antimeridian crossing on a North/South axis the largest liquid desert in the world, the Pacific Ocean so avoiding certain habitable land.
In crossing this line there is a date change of one day : the calendar day to the east of the line is one day earlier than it is to the west of the line.
Crossing the IDL traveling east results in a day or approximately 24 hours being subtracted, and crossing towards west results in a day being added.
So if one crosses the date line at precisely midnight, going westward, one skips an entire day; while going eastward, one repeats the entire day. 

Chatham islands
>>> geolocalization with the Marine GeoGarage <<<

 Kermadec islands
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Line date change diverges from the antimeridian being shifted eastward between 5° S and 51°20 'S to leave in the same time zone New Zealand's Chatham Islands in the east and far north-east, the Kermadec Islands (whose name is issued from Jean-Michel Huon de Kermadec who commanded the Espérance on the Bruni d'Entrecasteaux expedition to find the lost expedition of Jean-François de La Pérouse).

This difference does not affect the Vendée Globe racers who have both sailed south of the latitude 51° 20'S when they reach the Antimeridian (around 53° S).

The establishment of the prime meridian in Greenwich in 1884 permanently established the system of latitude and longitude and time zones that we use to this day.
Latitude and longitude is used in GPS and is the primary coordinate system for navigation on the planet.
Right now, Armel and François the two VG leaders have seen the longitude stop increasing to 180° (E) to decrease from 180° (W) : they really are into the second part of the race right now and on the road back – theoretically. The reality is they will sail to home 12,000 miles more...

Note : the term Anti-Meridian is sometimes confused with Ante Meridiem.
Ante Meridiem is latin for before noon. Usually shown in English as "a.m.".
Similarly, post meridiem, after noon, is shown in English as "p.m.".
 The map of the world showing Magellan's Route
(view in high resolution with the BNF )
The first date line problem occurred in association with the circumnavigation of the globe by Magellan's expedition (1519-1522).
The surviving crew returned to a Spanish stopover sure of the day of the week, as attested by various carefully maintained sailing logs.
Nevertheless, those on land insisted the day was different.
This phenomenon, now readily understandable, caused great excitement and confusion at the time, to the extent that a special delegation was sent to the Pope to explain this temporal oddity to him.
The effect of ignoring the date line is also seen in Jules Verne's book "Around the World in Eighty Days", in which the travelers, led by Phileas Fogg, return to London after a trip around the world, thinking that they have lost the bet that is the central premise of the story.
Having traveled the direction opposite to the one taken by Magellan, they believe the date there to be one day later than it truly is. 

Şekl-i Amerika (America), Ottaman Empire
The map of America, also called The New World, covers the region between the 60 degree parallels in the north and south.
The lines of latitude and longitude are drawn intersecting at right angles in the manner of Mercator.

Links :

Scarborough Shoal : long history of Philippines management

Bajo de Scarburo o de Masingloc (Scarborough Shoal).
Source: Edgardo Angara, Jose Maria Cariño and Sonia Ner. “Mapping the Philippines: The Spanish Period.” 2009.

From Inquirer / with maps from Em Esber blog (II)

(François-Xavier Bonnet, a French geographer, is a research associate at the Research Institute on Contemporary Southeast Asia [Irasec].
This article is excerpted from the author’s “Geopolitics of Scarborough Shoal,” Irasec Discussion Paper No. 14, November  2012, 42 pp 

Scarborough Shoal (Bajo de Masingloc and Panatag for the Philippines or Huangyan Island for China), located some 220 kilometers from the province of Zambales (Philippines), has been a bone of contention between the two countries since 1997.

 >>> geolocalization with the Marine GeoGarage <<<

Scarborough is the largest atoll in the South China Sea [West Philippine Sea], submerged at high tide with few rocks above sea level, but was largely unheard of before the implementation of the United Nations Convention on the Law of the Sea (Unclos) in 1994.
The shoal is inside the exclusive economic zone (EEZ) of the Philippines but is claimed by China as its ancestral territory since the Yuan dynasty (1271-1368).
This conflict, recurrent year after year during the fishing season, worsened from April to July this year.
This article focuses only on the geographical and historical links between the Philippines and the Scarborough Shoal.

 British boat wreck

On Sept. 12, 1748, a British boat named Scarborough, carrying tea, was wrecked on a feature called Maroona by Spanish cartographers.
Maroona Shoal became known internationally as Scarborough Shoal.
Maroona Shoal was first surveyed in April 1800 by a Spanish frigate, Santa Lucia, sent by Admiral Malaspina in Manila.

Topographic map of the Philippines drawn
under the direction of Ildefonso de Aragon, April 15, 1820.

A more precise survey of this feature was organized in May of 1866 by the British vessel H.M.S. Swallow under the command of E. Wilde.
However, with the island of Luzon being the closest to Bajo de Masingloc (124 nautical miles or 220 km), responsibility for rescuing vessels stranded at the shoal naturally fell on the Spanish Navy. Thus, according to the Spanish Hydrographic Office (1866), boats from the Philippines were sent to help crews in difficulty on this shoal.

Bureau of Navigation

This responsibility was transferred to the American colonial government in the archipelago.
For example, when, on May 8, 1913, the Swedish steamship Nippon went aground on Scarborough Shoal, the Bureau of Navigation in Manila sent the Coast Guard cutter Mindoro to help the stranded crew.
Moreover, a conflict arose between the salvaging company and the insurance companies for the sharing of the proceeds of the salvaged cargo (copra).
Litigants went to the Manila Court of First Instance and then to the Supreme Court of the Philippines.
The final judgment of the Supreme Court was recognized by the claimants.
The 19th century nautical books of the British Admiralty and the Spanish Hydrographic Office did not note the presence, on this shoal, of fishermen from China or elsewhere (unlike on the Spratly and Paracel Islands).
The geographical proximity spoke in favor of the Philippines (rescue operations).

Island of Panacot (Scarborough shoal)

Political, symbolic acts

In a way, Bajo de Masingloc could be seen as integrated in the sphere of influence of the Philippines, but outside the main archipelago.
Political and symbolic acts, like naming the shoal, surveying, map-making and organizing rescue operations, were the only appropriate activities that the Spanish and American authorities could do on an isolated shoal, which was, for the most part, underwater during high tide.
The main argument of the Chinese government and legal scholars is to consider the Philippine claim on Scarborough Shoal as extremely recent.
According to their writings, the Philippine government claimed this shoal for the first time in 1997.
Subscribers to this view contend that the atoll is outside the Treaty of Paris signed between Spain and the United States in December 1898, the Treaty of Washington between the United States and Spain on Nov. 7, 1900, and the Convention between Great Britain and the United States that was concluded on Jan. 2, 1930.
So, the Philippines cannot reasonably claim it.

Commonwealth claim

However, in the context of the southern expansion of the Japanese empire and the preparation for independence, the Commonwealth of the Philippines claimed in 1937-38 the Scarborough Shoal.
No less than President of the Commonwealth Manuel Quezon, US Secretary of State Cordell Hull and US Secretaries of War, Navy and Commerce concurred with this claim.
As they recognized that the Scarborough Shoal was outside the limits of the Treaty of Paris, they considered these limits as flexible and not fixed boundaries.
This flexibility could be shown by the fact that in 1900, the Philippines recovered some islands (Sibutu and Cagayan de Sulu) but lost the Island of Palmas in 1928 and gained the Turtle Islands and Mangsee Reef in 1930.
Thus, the transfer of the shoal could be done, with enough Spanish evidence, by invoking the Treaty of Washington of 1900.
Nevertheless, the bureaucratic process of the claim took nearly the whole year of 1938.
In 1939, the Japanese Navy took control of Hainan Island and Paracel Islands, and was pushing toward the Spratly Islands.
For security reasons, Scarborough Shoal was unofficially claimed.

Unofficial Sino claim

It is also for security reasons and not for historical reasons, that China claimed, unofficially, all the features in the South China Sea, among them, the Scarborough Shoal in 1935.
Thus, before the Second World War, in the context of Japanese expansion, the Philippines and China made parallel claims to Scarborough Shoal, each without knowing that the other was doing the same.
Both claims were unofficial in the sense that there was no notice to the whole world to avoid attracting the attention of the Japanese.
Nevertheless, in the case of the Philippines, the State Department had more specific information about Scarborough Shoal than the Chinese had.
For the Chinese government, Scarborough Shoal was simply one small feature among all the South China Sea islands and reefs.
It had no information about this shoal but was expecting that in the future its researchers would find some evidence of Chinese ownership.
In conclusion, the Chinese claim was as recent or as old as the one of the Philippines.
From the end of the Second World War up to the 1990s, Scarborough Shoal was largely ignored by the governments of China and Taiwan. In some international conferences, the two Chinese governments would claim regularly that the Xisha, Zhongsha and Nansha islands were part of their territories, but no specific actions were taken concerning Scarborough Shoal.

Too close to US base

This shoal was too close to Subic Bay, the main American naval base in Asia. In the context of the Cold War, the main ally of the United States, Taiwan and the far away mainland China would not risk trying to take control of a mostly underwater reef.
The first official mission on this shoal by Chinese authorities was made in 1978. In effect, that year, the Earthquake Bureau and Oceanic Administration made a survey of Scarborough Shoal. In 1983, the shoal was renamed Huangyan Qundao (Huangyan Islands).

Cavite smugglers

In the Philippines, the name of Scarborough Shoal appeared in the newspapers mostly in relation to smuggling activities of syndicates based in the province of Cavite and abroad.
In October 1963, for example, the Philippine Navy discovered that the shoal was used as an entry point for smuggled goods (cigarettes, etc.) from Macau.
The contraband was carried by Taiwanese fishermen.
According to news reports, the international syndicate built two bodegas and some pier facilities on the shoal.
Fishermen from the Philippines working for the Filipino side of this syndicate loaded goods on their boats and unloaded them on various beaches of Luzon.
These well-organized international private activities were simply using loopholes of maritime laws of the time.
The status of a shoal in the high seas was still not clear.
The Philippine Navy arrested the Filipino fishermen (a Taiwanese boat was pursued by a Filipino boat but it was able to escape) and bombed, on orders of Defense Secretary Macario Peralta, the facilities built by the syndicate.
This bombing followed an aerial mission by the Philippine Air Force over the shoal.

No Chinese protest

It should be noted that these state activities (fighting smuggling and bombing the structures on the shoal) undertaken by the Philippine Navy were not protested by Taiwan or China.
Another investigation in March 1964, under the Senate blue ribbon committee, confirmed once more these smuggling activities on the shoal.
It is probably the reason that, following these investigations, a Filipino flag was raised on an 8.3-meter pole and that the government built in 1965 and operated a small lighthouse on Scarborough Shoal.

First confrontation

Thus, the activities of the Filipinos on Scarborough Shoal in the 1960s went unchecked and were not protested by the two Chinas.
Then on May 1, 1997, when Philippine Navy ships intercepted an international amateur radio team sponsored by China on Scarborough Shoal and later arrested 21 Chinese fishermen, the incident started the first confrontation between the two countries over the shoal.
On the Chinese side, it was perceived as the first time the Philippines dared to challenge China’s sovereignty over the shoal.
But, in light of what we said earlier, the Philippines could easily turn the argument against China.

 Navy personnel and Philippine MPs at the tiny rock of Scarborough Shoal
bearing Philippine flag in South China Sea in 1997.
Picture: AFP (photos)

Under PH regime of islands

President Gloria Macapagal-Arroyo signed on March 10, 2009, the new law on the baselines (Republic Act No. 9522) declaring Scarborough Shoal outside the main archipelago but under the regime of islands.
It was in conformity with Unclos and the historical links between the shoal and the Philippines.
In fact, as we have seen, the shoal could be perceived as a special territory since the 19th century (under the sphere of influence of the Philippines) and confirmed as such by its exclusion from the different baseline laws of 1961, 1968 and 2009.
The various State activities on the shoal, like organizing rescue operations, fighting smuggling activities, building a lighthouse, or more recently arresting poachers, are consistent with the nature of a low-tide elevation and its isolation from the main archipelago, and with the sovereign rights of the State in its EEZ.
The Chinese government has criticized the Philippine position as inconsistent with the Constitutions of 1935, 1973 and 1987, as they refer to the Philippine territory through the colonial treaties, excluding de facto the shoal.
However, first, neither of the postcolonial constitutions referred to the different treaties signed by the American from 1898 to 1930.

National territory

In both Constitutions, the national territory is described as comprising “the Philippine archipelago, with all the islands and waters embraced therein.”
No details were given on the geographical coordinates of the archipelago.
Second, as we have seen, the shoal was claimed in 1938 and the two Constitutions (1973 and 1987) specify that the national territory of the Philippines comprise “all other territories over which the Philippines has sovereignty or jurisdiction.”
Thus, it would be logical to consider that Scarborough Shoal belongs to this category, “other territories.”

American conundrum

Can the United States be dragged into the Sino-Philippine dispute over Scarborough Shoal?
The United States has repeatedly said it does not take sides in these territorial disputes but enjoined the claimants to resolve their differences peacefully in accordance with international law and freedom of navigation.
However, this principle of neutrality is counterbalanced by the treaty obligations of the United States. The 1951 Mutual Defense Treaty (MDT) can be invoked in three cases of attacks:
  1. on the metropolitan territory of the Philippines (or the United States);
  2. on the island territories under the jurisdiction of the Philippines (or the United States) in the Pacific Ocean;
  3. on the armed forces, public vessels, or aircraft of the Philippines (or the United States) in the Pacific Ocean.
Before MDT signing

If we apply the MDT to the case of Scarborough Shoal, several remarks can be made.
Since the promulgation of the 2009 baseline law, the Philippine government clearly does not consider the shoal part of its metropolitan territory.
However, as we have seen, the claim over Scarborough Shoal was made some 13 years before the signing of the MDT.
If the expression “Pacific Ocean” integrates also the South China Sea, Scarborough Shoal could possibly be considered part of the category “island territories.”
Moreover, an attack on any public boat of the Philippines patrolling around the shoal could prompt the decision to invoke the MDT.
The United States and the Philippines can develop a “strategic ambiguity” on the possible use of the treaty.
This strategy could “help protect the Philippines and peace and stability in the South China Sea.”

Links :
  • GeoGarage blog : Philippines, China commit to diplomacy to end Scarborough standoff

Thursday, December 20, 2012

Vendee Globe : crossing the subantarctic islands of New Zealand

Crossing NZ longitude

>>> geolocalization with the Marine GeoGarage <<<

South West Cape
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South West Cape is a cape on the south coast of Stewart Island, New Zealand.
It is the southernmost point on the island, and as such is almost the southernmost point on the main chain of islands that make up New Zealand,
beaten to that honour by the tiny Murphy Island, which lies some three kilometres to the west and some 100 m further south. 

Stewart Island (NZL) 11th-17th January 2001(Port Pegasus)- Vendée Globe 2000/2001.
>>> geolocalization with the Marine GeoGarage <<<
Yves Parlier (FRA) Open 60' skipper "Aquitaine Innovations" in Steward Island fixing his broken mast on his own without assistance respecting Race rule.
 Yves finished his round the world with his mast fixed in Stewart Island.  
"Aquitaine Innovation" arriving in Port Pagasus, with a broken mast !
see photos on Sea&Co

 The Western Chain

The New Zealand Sub-Antarctic Islands has five island groups (the Snares, Bounty Islands, Antipodes Islands, Auckland Islands and Campbell Island) in the Southern Ocean south-east of New Zealand, occupying the stormy latitudes of the Roaring Forties and the Furious Fifties, known also as the Albatross Latitudes.
The islands situated between the Antarctic and Subtropical Convergences and the seas, have a high level of productivity, biodiversity, wildlife population densities and endemism among birds, plants and invertebrates.
They are particularly important resident for the large number of pelagic seabirds and penguins that nest there.
There are 126 bird species in total, including 40 seabirds of which five breed nowhere else in the world.

The New Zealand Sub-Antarctic Islands shows a pattern of immigration of species, diversification and emergent endemism, provides particularly good opportunities for research into the dynamics of island ecology.
The New Zealand Sub-Antarctic Islands are remarkable for their high level of biodiversity, population densities, and for endemism in birds, plants and invertebrates.
The bird and plant life, especially the endemic albatrosses, cormorants, petrels, shearwaters, fulmars, prions -and “megaherbs” are unique to the islands.
Penguins too, are special in the Sub Antarctic region. 
Of seven penguin species breeding here, three (Snares crested, Erect crested and Royal) are endemic to the region.
The land birds indicate, through their diversity, just how long these islands have been isolated.

North East Island, NZ
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The North East Island is the main island of the Snares Island group, approximately 200 kilometres (120 mi) south of New Zealand's South Island.
The island forms a central triangle with peninsulas to the north, south and to the west and is some 3 by 2.5 km (1.9 by 1.6 mi) long by wide. Off the South Promontory lies Broughton Island, the second largest island in the group. South off the western peninsula coast lies the islet Alert Stack and off the North Promontory lies the North and South Daption Rocks.
The highest elevation of 130 m (427 ft) is at the western peninsula.

The southwest part of North East Island, Snares Islands, where the coastline is oriented to the northwest, showing the rocky cliffs that are typical of much of the south, west and north coasts exposed to prevailing westerly storms.
Photo Copyright © 2004 Tui De Roy, Roving Tortoise Worldwide Nature Photos

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The Bounty Islands are a small group of 13 uninhabited granite islets and numerous rocks in the south Pacific Ocean that are territorially part of New Zealand. It lies about 670 km (416 mi) east-south-east of the South Island of New Zealand, and 530 km south-west of the Chatham Islands.
The Bounty Islands were discovered by Captain William Bligh in 1788 and named after his ship, HMS Bounty, just months before the famous mutiny.
During the 19th century, they were a popular hunting ground for sealers.

 The Bounty Islands are literally rocks in the ocean.

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The Antipodes Islands are inhospitable volcanic islands to the south of—and territorially part of—New Zealand. They lie 860 kilometres (534 mi) to the southeast of Stewart Island/Rakiura

View from the Antipodes

Auckland islands
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The Auckland Islands are an archipelago of the New Zealand subantarctic islands and include Auckland Island, Adams Island, Enderby Island, Disappointment Island, Ewing Island, Rose Island, Dundas Island and Green Island.
They lie 465 kilometres (290 mi) from the South Island port of Bluff.
The islands have no permanent human inhabitants.

Photo : Andris Apse
(other photos of Auckland islands)

"During my second Vendée Globe, I thought of stopping on the Auckland Islands south of New Zealand, however, this is not easy to do in an Open 60. I said to myself that the JP 54 would have to be able to anchor in a bay or set off again in less than 10 minutes. The pleasure of sailing comes with the ease with which you can discover a place.” Jean-Pierre Dick (31/12/2008)
Campbell Island 
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 Campbell Island is a remote, uninhabited, subantarctic island of New Zealand and the main island of the Campbell Island group.
The island is surrounded by numerous stacks, rocks and islets like Dent Island, Folly Island, Isle de Jeanette Marie, and Jacquemart Island, the latter being the southernmost extremity of New Zealand.
The Island is mountainous, rising to over 500 metres (1,640 ft) in the south.
A long fjord, Perseverance Harbour, nearly bisects it, opening out to sea on the east coast.

Landscape, Campbell Island with Jacquemart Island in the background.
Macquarie Island
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Macquarie Island (or Macca) lies in the southwest corner of the Pacific Ocean, about half-way between New Zealand and Antarctica.
About 1500 km south east of Tasmania, Macquarie Island is a tiny fragment of land between Tasmania and Antarctica in the Southern Ocean.

Politically, it is part of Tasmania, Australia since 1900 and became a Tasmanian State Reserve in 1978.
In 1997 it became a World Heritage Site.

The island is home to the entire Royal Penguin population on earth during their annual nesting season.
Ecologically, it is part of the Antipodes Subantarctic Islands tundra ecoregion.

New 3D maps show walruses' icy world

Walrus gathered on sea ice (NOAA)

Walruses are sort of the Goldilocks of the North Pole — the chunks of sea ice they call home must be just right.
If the ice floe is too large, the walrus can't get to water quickly enough to escape a polar bear attack; too small, and the ice can't support their weight and the walruses go splashing into the sea.

Two polar bears seen on the Arctic ice during a research cruise to map the ice in 3D.
Credit: Scott Sorensen

Now, a new technique for mapping the 3D structure of Arctic ice promises to help researchers better understand the habitat needs of walruses and other wildlife.
The 3D ice maps could also aid in planning shipping routes, research cruises and other Arctic endeavors, said Chandra Kambhamettu, a computer scientist at the University of Delaware who developed the technique.

"We're interested in objectively characterizing these habitats and how they're changing over time, as well as how to measure the effects of warming on the region," Kambhamettu told OurAmazingPlanet.

German research vessel Polarstern used during an Arctic expedition to map sea ice in 3D.
Credit: Scott Sorensen

Kambhamettu's team used the system, which relies on two cameras mounted to a research vessel, on a recent two-month cruise that traversed nearly 10,400 miles (17,000 km) of the Arctic Ocean. 

On thin ice: Mapping walrus habitat in 3-D

The 5-megapixel single lens reflex cameras, which are mounted to the ship side-by-side, 2 meters (6.6 feet) apart, capture a new high-resolution image each second.
Because the cameras work in stereo — capturing simultaneous images from opposing angles, like our own eyes — Kambhamettu's team can resolve the depth of the ice from the images.
They have developed algorithms to match images from the left camera to ones from the right camera, and an algorithm that can recognize subtle textures within the bright white chunks of ice.

"Like the stereo camera system, humans also see objects through two eyes, but we just automatically understand what's near or far from us," Kambhamettu said.
"The computer system doesn't have the same intuition, so we have to write algorithms to get those measurements."

To be sure, his team isn't the first to use stereo photography to reconstruct a landscape in 3D.
But his team's recent Arctic expedition seems to be the first instance of researchers using stereo photography to measure 3D changes in ice cover over time, Kambhamettu said.

The technique produces maps with greater detail than radar or satellite images, and it's about one-tenth the cost of LiDAR (light detection and ranging), a type of laser radar that produces comparable data.

A database with ice-depth maps and habitat data collected during the recent expedition should be up and running — and open to other researchers — by summer 2013, Kambhamettu said.

Links :
  • VIMS : Polar Sea-Ice Topography Reconstruction System (PSITRES)

Wednesday, December 19, 2012

NOAA Coast Survey cartographers update and maintain over a thousand nautical charts


During the first six months of the Coast Survey blog, we have focused largely on the field work – surveying sparsely charted Arctic waters, responding to calls for help following hurricane destruction, finding dangers to navigation, and even identifying historic wrecks.

We haven’t covered the day-in, day-out job that is our reason for existence: creating and updating the country’s nautical charts.
Coast Survey has compiled and maintained the nation’s nautical charts for nearly two centuries, after President Thomas Jefferson approved legislation in the Ninth Congress in 1807, and we now maintain a suite of over a thousand charts.

We sometimes get the question, “aren’t you done yet?”
Haven’t we finished charting all of the U.S. waters?
The simple answer is no: because storms alter seafloors, and water depths constantly change due to shifting shoals, submerged hazards, and coastal development, Coast Survey must continually update the nation’s nautical charts.
Charting those changes, and ensuring chart accuracy and precision, is essential to protecting life and property.

The more complicated answer may surprise you.
Many of our nation’s marine shipping lanes, harbors, and port areas haven’t been mapped since the 1920s, when measurements weren’t as precise – or even as accurate ‒ as is possible now.
Some areas, especially in Alaska, haven’t had bottom measurements since the mid-1770s.

Coast Survey’s Marine Chart Division employs many of the nation’s best cartographers.
Since 2009, cartographers have applied approximately 50,000 critical charting corrections to NOAA’s various charting products.
In fiscal year 2012 alone, cartographers applied more than 11,000 critical corrections to chart updates.

Over those four years, Coast Survey has also produced over 500 new chart editions (of current charts), and built 200 new NOAA ENC® (NOAA electronic navigational charts).
This includes 155 new chart editions and 56 new ENCs in fiscal year 2012. 

Coast Survey issued new Kotzebue chart 16161, partially depicted here, in May 2012.
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This year, Coast Survey produced several brand new nautical charts, including a new chart for the Port of San Juan, Puerto Rico, and for the Kotzebue Harbor in Alaska, where increasing ocean commerce required improved navigational products.
Coast Survey also released an updated chart of Norfolk Harbor, with a new inset of the Inner Harbor, which has developed as a multi-purpose port area.

In addition to updating old charts, and creating new ones, Coast Survey is making more information accessible from its electronic navigational charts.
Effective early 2012, several of NOAA’s ENCs that cover the approaches to the East Coast now alert mariners when they are approaching the right whale seasonal management areas, giving them better information to plan to reduce their speeds or avoid the areas altogether.
The seasonal management areas, as encoded into the ENCs, graphically show the areas where vessels greater than 65 feet in length must travel at 10 knots or less to reduce the risk of collisions with right whales.
The ENCs will also provide for an alarm on the ship’s electronic chart display and information system as vessels enter the speed zone, further alerting the bridge watchstander of speed restrictions.

We are seeing a gradual shift from paper nautical charts to raster navigational charts and electronic navigational charts.
Over the last four years, the public has purchased nearly 428,000 print-on-demand paper charts, and another 392,000 traditional paper charts.
Reflecting the booming technology in navigation, the public has downloaded countless millions of the electronic and raster navigational charts that NOAA offers free on the Internet.

Even while cartographers use their expertise to update and innovate, there is still the matter of uncharted U.S. waters – waters that remain to be surveyed.
Coast Survey is mandated to provide nautical charts for all U.S. territorial waters and the U.S. Exclusive Economic Zone, a combined area of 3.4 million square nautical miles that extends 200 nautical miles offshore from the nation’s coastline.
A complete survey of all of those waters would require 545 ship years and $5 billion just to acquire the data.
Lacking those resources, NOAA has instead established priorities for the hydrographic surveys that acquire data necessary for reliable charts.
Those priorities are updated annually, and are available on Coast Survey’s website, as NOAA Hydrographic Survey Priorities.

A critical need for new or updated charts is especially emerging in the Arctic, and Coast Survey’s Arctic Nautical Charting Plan addresses the tasks ahead.
Commercial mariners and recreational boaters will always rely on NOAA’s charts to keep them and their passengers and cargo safe from harm.
NOAA’s cartographers will always work to earn that trust.

If you note a chart discrepancy, please report it through our online service.