MH370 spur to 'better ocean mapping'

Seafloor topography in the Malaysia Airlines flight MH370 search area.

Dashed lines approximate the search zone for sonar pings emitted by the flight data recorder and cockpit voice recorder popularly called black boxes.

The first sonar contact (black circle) was reportedly made by a Chinese vessel on the east flank of Batavia Plateau (B), where the shallowest point in the area (S) is at an estimated depth of 1637 meters.

The next reported sonar contact (red circle) was made by an Australian vessel on the north flank of Zenith Plateau (Z).

The deepest point in the area (D) lies in the Wallaby- Zenith Fracture Zone at an estimated depth of 7883 meters.

The Wallaby Plateau (W) lies to the east of the Zenith Plateau.

The shallowest point in the entire area shown here is on Broken Ridge (BR).

Deep Sea Drilling Project (DSDP) site 256 is marked by a gray dot.

The inset in the top left shows the area’s location to the west of Australia. 

Seafloor
depths are from the General Bathymetric Chart of the Oceans [2010].

From BBC by Jonathan Amos

Scientists have welcomed the decision to make all ocean depth data (bathymetry) gathered in the search for missing Malaysia Airlines flight MH370 publicly available.

A detailed survey of 60,000 sq km of seabed is to be undertaken to help refine the hunt for the lost jet.
The depth and shape of Earth's ocean floor is very poorly known.
Leading researchers say the MH370 example should be a spur to gather much better data elsewhere in the world.
The search has been hampered by the lack of a high-resolution view of the bed topography west of Australia.
This was apparent on the very first dive made by an autonomous sub investigating possible sonar detections of the aircraft's cockpit voice and flight data recorders.
It was forced to cut short the mission because it encountered depths that exceeded its operating limit of 4,500m. There are places thought to exceed 7,800m.

Australian Transportation Safety Board (ATSB) officials said this week that an area in the southern Indian Ocean the size of Tasmania would now be subject to a full survey using multibeam echo sounders (MBES).
A Chinese navy vessel, Zhu Kezhen, has already started on the project.
It will be joined by a commercial ship in June, with the work likely to take three months.

Trackline Geophysical Data Viewer

Drs Walter Smith and Karen Marks have assessed the paucity of bathymetric data in the region in an article for EOS Transactions, the weekly magazine of the American Geophysical Union.
The pair work for the US National Oceanic and Atmospheric Administration (Noaa).
They say only two publically accessible data-acquisition sorties have been conducted close to where search vessels made possible black box detections, and "both expeditions occurred prior to the use of modern multibeam echo sounders, so depth measurements were collected by single, wide-beam echo sounders that recorded on analogue paper scrolls, the digitizing of which is often in error by hundreds of metres".

Topex

Modern MBES uses GPS to precisely tie measurements to a particular location.
The equipment can not only sense depth very accurately (to an error typically of 2%), but can also return information on seafloor hardness - something that would be important in looking for wreckage in soft sediment.
Just 5% of a vast region, 2,000km by 1,400km, which includes the search locality, has any sort of direct depth measurement, Smith and Marks say.
The rest - 95% - is covered by maps that are an interpolation of satellite data.
These have a resolution no better than 20km. Maps of the arid surface of Mars are considerably better.

"The state of knowledge of the seafloor in the MH370 search area, although poor, is typical of that in most of Earth's oceans, particularly in the Southern Hemisphere," the pair write.
"In many remote ocean basins the majority of available data are celestially navigated analogue measurements because systematic exploration of the oceans seems to have ceased in the early 1970s, leaving the ocean floors about as sparsely covered as the interstate highway system covers the United States.
"When these sparse soundings are interpolated by satellite altimetry, the resulting knowledge of seafloor topography is 15 times worse in the horizontal and 250 times worse in the vertical than our knowledge of Martian topography."

 West Australia bathymetry with AHS nautical chart (Marine GeoGarage)

Smith and Marks hope that the detailed survey work now being conducted in the search for MH370 will be a catalyst to gather better data in other parts of the globe.
High-resolution bathymetry has myriad uses.
"Better knowledge of the ocean floor means better knowledge of fish habitats. This is important for marine conservation, and could help us find biological resources including new medicines," Dr Smith told BBC News.
"It means also a better ability to assess the mineral resource potential of the seabed. And it means better knowledge of the obstacles to flow that cause turbulence and mixing in the oceans.
"We need this mixing and circulation information to make good models of future climate. All of these things depend on knowing the topography of the sea floor."

The Australian Joint Agency Coordination Centre, which disseminates all information on the hunt for MH370, confirmed that the MBES survey data would be publicly available.
"The bathymetry data gathered in the course of the search for MH370 will become the property of the Australian Government. Recognising the importance of that data, it will be made available to the public via both Australian and international databases," the JACC told the BBC.

• Most ocean maps are derived from satellite altimeter measurements
• Satellites infer ocean-floor features from the shape of the sea surface
• They detect surface height anomalies driven by variations in local gravity
• The gravity from the extra mass of mountains makes the water pile up
• In lower-mass regions, such as over troughs, the sea-surface will dip
• Limited high-resolution ship data has calibrated the satellites' maps

On Tuesday, all the raw satellite data from the London telecommunications company Inmarsat was also put in the public domain.
It was this information that led investigators to look for wreckage in the southern Indian Ocean.

Links :

• GeoGarage blog : Malaysia Airlines flight MH370: Satellite data to be re-examined as ‘more difficult’ phase begins, search on ocean floor widened / MH370: How do underwater sonar subs work? / Appeal to search missing Malaysian flight / Why locating MH370 in the Southern Ocean is so difficult / Malaysia Airlines Flight MH370: Search reveals extent of ocean garbage / Malaysia missing plane search China ship 'picks up signal'

Changes on the Cape Cod coastline

 NASA, acquired June 12, 1984

 NOAA nautical chart  #13248-8 (1986)
Chatham Harbor and Pleasant Bay
 

NASA, acquired July 30, 2013
download Google Earth file (KML)  acquired 1984-2013

 NOAA nautical chart upon Google imagery on the Marine GeoGarage

From NASA

Beaches are dynamic, living landscapes, and the prime example of beach evolution is the coastal barrier.
These strips of land are usually long and narrow, and run parallel to the mainland.
Sometimes they are islands and other times they are connected to land at one end, a feature dubbed a “spit.”
Scientists estimate that there are more than 2,100 barriers fronting nearly 10 percent of the world’s continental shorelines.
In the United States, barrier spits and beaches line up along nearly a quarter of the coast.

These sandy barriers are constantly raised up, shifted, and torn down by the natural ebb and flow of waves, currents, winds, and tides.
Hooks form, inlets open and close, and beaches slowly march across their back bays and lagoons toward the mainland.
This process allows them to naturally move ever upwards as sea levels rise.

On the southeastern elbow of Cape Cod, where the New England coast reaches out into the cold and choppy North Atlantic, this natural progression has been taking place in full view of satellites for more than 30 years.
The images above were acquired by the Operational Land Imager on Landsat 8 (top) and the Thematic Mapper on Landsat 5 (bottom).
They show the shape of the coast off of Chatham, Massachusetts, on June 12, 1984, and July 30, 2013.

 Turn on the image comparison tool for an easier view of the changes (1984-2013)

Visit our longer World of Change time series to see the years in between.

The changes to the Nauset-Monomoy barrier system in this part of Cape Cod are sometimes subtle and sometimes dramatic.
In 1984, an unbroken barrier spit shielded the Atlantic-facing coast of Chatham and its harbor.
South of the mainland, North and South Monomoy Islands stood apart from each other and from the coast.
Over the span of 30 years, three major breaches opened in the system and the barrier islands connected to the coastline and to each other.

According to Graham Giese, a coastal geologist at the Provincetown Center for Coastal Studies, the patterns of barrier and inlet evolution in this area have been going on for at least the past three hundred years, and perhaps longer.
The landmass was laid down at the end of the last Ice Age as the Laurentide ice sheet retreated and rivers and streams of melt water dropped sediment and carved the landscape.
As sea level rose over the past 10,000 years, the ocean ate at the glacial deposits that lay as far as four miles offshore of the present coast.
Sea cliffs—some towering over 100 feet high—were created by wave action, while strong winds produced great dunes.
These features are protected today in the Cape Cod National Seashore.

Giese and other researchers have identified a recent cycle of beach development and migration around Chatham that seems to repeat roughly every 150 years.
Depending on your location along the coast and your timing, the movement of sand around you may be driven by ocean waves or by tides.
Waves usually dominate, promoting longshore transport.
High-energy open-ocean waves from the Atlantic crash into the Nauset-Monomoy barrier system at various angles, scouring the sandy glacial leftovers and creating currents that run parallel to the shore. Erosion along the Nauset-Monomoy barrier system can move the beach anywhere from 1 to 6 meters a year (3 to 20 feet).
Sea level rise—a least one foot in the past century—is also slowly taking away the beachfront.

“Many people view coastal erosion as a problem that needs to be addressed and, if possible, prevented,” wrote coastal geologist Robert Oldale of the U.S. Geological Survey.
“However, storm and wave erosion along the shore of Cape Cod has been going on for thousands of years and will likely continue for thousands of years more. It is a natural process that allows the Cape to adjust to rising sea level. Erosion is only a peril to property. If we build on the shore, we must accept the fact that sooner or later coastal erosion will take the property away.”

Links :

• Changes to barrier beaches and Cape Cod in World of Change: Coastline Change.

Deep Water

Videos from Bernard Moitessier's journey around the world single handed in 1968,
Footage from the movie "Deep Water" about Donald Crowhurst's suicide at sea.

Links :

• GeoGarage blog : Deep water : an unforgettable journey into one man's heart of darkness

Guide to racing a Laser

Sailing can be seen as rather complicated, if you need some help understanding watch this video staring Shirley Robertson and Olympian Alison Young on Laser.

Shirley demonstrates and talks you through the perfect start, tacking and crossing, getting ahead at the top mark and priority at the bottom mark.

How oceans can solve our freshwater crisis

"Drinking from the sea", explore how and why sea water is desalinated

From CNN

It's been a cruel irony for ancient mariners and any thirsty person who has ever gazed upon a sparkling blue ocean: Water, water everywhere, and not a drop to drink.

But imagine a coastal city of the future, say in 2035.
Along with basic infrastructure such as a port, roads, sewer lines and an electrical grid, it's increasingly likely this city by the sea will contain a newer feature.

A desalination plant.

Thanks to improved technology, turning ocean water into freshwater is becoming more economically feasible.

And a looming global water crisis may make it crucial to the planet's future.

The United Nations predicts that by 2025, two-thirds of the world's population will suffer water shortages, especially in the developing world and the parched Middle East.

Scientists say climate change is making the problem worse.

Even in the United States, demand for water in drought-ravaged California and the desert Southwest is outpacing supply.

San Diego's billion-dollar water bet

This is why a huge desalination plant is under construction in Carlsbad, California, some 30 miles north of San Diego.

When completed in 2016, it will be the largest such facility in the Western Hemisphere and create 50 million gallons of freshwater a day.

"Whenever a drought exacerbates freshwater supplies in California, people tend to look toward the ocean for an answer," said Jennifer Bowles, executive director of the California-based Water Education Foundation.

"It is, after all, a seemingly inexhaustible supply."

A growing trend

Most desalination technology follows one of two methods: distillation through thermal energy or the use of membranes to filter salt from water.

In the distillation process, saltwater is heated to produce water vapor, which is then condensed and collected as freshwater.

The other method employs reverse osmosis to pump seawater through semi-permeable membranes -- paper-like filters with microscopic holes -- that trap the salt while allowing freshwater molecules to pass through.

The remaining salty water is then pumped back into the ocean.

An Introduction to the Carlsbad Desalination Plant Project :

The Carlsbad Desalination Project will provide San Diego County with a locally-controlled, drought-proof supply of high-quality water that meets or exceeds all state and federal drinking water standards.
After ten years of planning and six years in the state's permitting process, the Carlsbad Desalination pipeline has now received final approvals from every required regulatory and permitting agency in the state, including the California Coastal Commission, State Lands Commission and Regional Water Quality Control Board.
A 30 year Water Purchase Agreement is in place between the San Diego County Water Authority and Poseidon for the entire output from the plant.
Construction has already started and is expected to be complete in mid-2016.

Officials at the Carlsbad plant say they can covert two gallons of seawater into one gallon of freshwater by filtering out 99.9% of the salt.

There are some 16,000 desalination plants on the planet, and their numbers are rising.

The amount of desalted water produced around the world has more than tripled since 2000, according to the Center for Inland Desalination Systems at the University of Texas at El Paso.

"Desalination is growing in arid regions," said Tom Davis, director of the center.

"We are making progress in the USA, but the countries around the Persian Gulf are way ahead in the use of desalination, primarily because they have no alternative supplies of freshwater."

Israel, in an arid region with a coastline on the Mediterranean, meets half its freshwater needs through desalination.

Australia, Algeria, Oman, Saudi Arabia and the United Arab Emirates also rely heavily on the ocean for their municipal water.

In the United States, desalination projects are concentrated in coastal states such as California, Florida and Texas.

Some environmentalists are wary of desalination, which consumes large amounts of energy, produces greenhouse gases and kills vital marine organisms that are sucked into intake pipes.

But proponents believe the technology offers a long-term, sustainable solution to the globe's water shortages.

One entrepreneur has even built an experimental solar desalination plant in California's San Joaquin Valley.

"When other freshwater sources are depleted, desalination will be our best choice," said Davis, a UTEP professor of engineering.

California dreaming

Within the United States, the water crisis is especially severe in California, which has been stricken by drought over the last three years.

California's biggest source of freshwater is the snow that falls in the Sierras and other mountains, where it slowly melts into creeks and makes its way into aquifers and reservoirs.

But if the planet continues to grow warmer, snow will increasingly fall as rain and will be harder to collect because it will swell creeks faster and create more flooding, said Bowles of the Water Education Foundation.

Seventeen desalination plants are being built or planned along the state's 840-mile coastline.

City officials in Santa Barbara recently voted to reactivate their desalination plant, which was built in 1991 but shut after heavy rains filled nearby reservoirs in the early 1990s.

Another $200 million facility has been proposed for the Bay Area, although construction won't likely begin for several years.

"The key question with ocean desalination is how much are you willing to pay for it? The amount of energy required to desalt ocean water can be daunting," said Bowles, adding that operating costs at the Santa Barbara plant alone are estimated at $5 million per year.

But advocates believe the price of desalination will continue to decrease as the process improves. This will be true of the massive Carlsbad plant, said Bob Yamada, water resources manager with the San Diego County Water Authority.

"The cost for this water will be about double what it costs us to import water into San Diego," Yamada said.

"However, over time we expect that the cost of desalinated water will equal, and be less than, the cost of imported water. That may take 15 or 20 years, but we expect that to occur."

Ultimately, experts say, municipalities will need to balance desalination projects with conservation and water from more traditional sources, such as rivers, reservoirs and recycled wastewater.

"You can't get all your water from one source and have that source be hundreds of miles away," said Peter MacLaggan, senior vice president at Poseidon Resources Corporation, which is leading development of the Carlsbad plant.

"When and if the drought does come, and you don't have enough snowpack in the Sierras -- after 12 dry years the Rockies are seeing the impact of that today -- you've got (water) sources here within the boundaries of San Diego County," he said.

"We have a $190 billion economy in this region. It's dependent on water to sustain that economy. So the question you need to consider, is 'What's the cost of not having enough water?'"