sail-world.com
 
 
News Home Boats for Sale MarineBusiness-World Sail-World Racing Cruising Int Magnetic Is RW Photo Gallery FishingBoating
Sail-World.com : Researcher examines 'current leaks' that may change the way you sail
Researcher examines 'current leaks' that may change the way you sail

'Isabela Le Bras stands near a flotation sphere for a Line W mooring during a cruise to maintain the observatory. (Photo courtesy of Jinbo Wang, Scripps Institution of Oceanography) -'    Jinbo Wang, Scripps Institution of Oceanography

Isabela Le Bras, a graduate student in the MIT/WHOI Joint Program in Oceanography, is investigating how ocean currents - those marvellous currents that, taken advantage of, can speed sailors' voyages around the world - interact in the total story of the Earth's changing climate. How they might change in future could also affect the temperatures you will sail in at the equator and the poles. Here is her progress report, fascinating and alarming in some aspects:

Within the ocean, there’s a global highway system of currents which are major cogs in our planet’s heating and ventilation system. They transport heat across the planet, from the equator to the poles. If not for these currents, the equatorial ocean would be a scalding hot tub and the Polar Regions would freeze solid.

2 - Detours on Oceanic Highway -  WHOI Graphic Services  

Imagine the Earth as a poorly insulated apartment—a railroad flat with three rooms. The kitchen in the middle is heated by a woodstove, but the two unheated outlying bedrooms can get cold. Earth’s kitchen is the equatorial region, heated by sun; the far-flung poles are its chilly bedrooms.

But open the doors between rooms in the apartment, and warm air moves out from the middle room and heats up the bedrooms a little, while colder air circulates in and cools the kitchen. Our ocean works essentially the same way, but rather than air, great ocean currents circulate excess equatorial heat to the poles.

In the North Atlantic, for example, the Gulf Stream carries water warmed at the equator toward the North Pole. When the warm water meets frigid winter air in northern latitudes, it cools vigorously. Water becomes denser as it cools, and consequently sinks thousands of meters below the sea surface. This deep mass of cold water drifts southward in a current that hugs North America's continental slope on the western side of the Atlantic Ocean basin: the Deep Western Boundary Current.

These currents are major cogs in our planet’s heating and ventilation system that regulate Earth’s climate. To understand how our climate works and unravel how it will change, we need to reveal the inner workings of these currents.

A mathematical ocean

3 - Detours on Oceanic Highway -  WHOI Graphic Services  

As recently as 50 years ago, the Deep Western Boundary Current remained undiscovered. Oceanographers knew that water must be sinking at high latitudes, but they did not have the means to observe where it went. In the early 1960s, two scientists at Woods Hole Oceanographic Institution (WHOI), Henry Stommel and Arnold Arons, used mathematics to explore deep-sea circulation. Reducing the problem to its bare essentials, they conceived of an idealized ocean that looked more like a bathtub. It had straight walls, a flat bottom, and water sinking at the ends of the tub, which represented the real-world polar oceans.

In this theoretical model, they calculated the essential physical forces acting on the flow of water in bounded basins on a rotating sphere. Their calculations pointed to the existence of the Deep Western Boundary Current. A few years later, English oceanographer John Swallow and Val Worthington at WHOI placed floats in the ocean. The floats were swept equatorward by the Deep Western Boundary Current, confirming what Stommel and Arons had predicted by mathematical equations alone.

Physical oceanographers have continually used this combination of observations and models to push forward our understanding of ocean dynamics. Models are mathematical approximations of reality that can distill the essence of the physics at work and help us explore how the world operates. Observations confirm the reality and unveil new complexities that require further explanation.

Tollbooths on the ocean highway

   WHOI Graphic Services  

One important set of observations has come from Line W, where scientists at WHOI have been measuring the strength of the Deep Western Boundary Current in the North Atlantic since 2004. Line W consists of a series of six moorings that starts at the continental slope off Cape Cod, Mass., and heads southeast. Moorings consist of cables as tall as ten Empire State Buildings. The cables are anchored to the ocean floor and held upright by buoyant glass spheres. Instruments called moored profilers ride up and down along the cables, measuring the temperature, salinity, depth, and velocity of the water as it flows by.

   WHOI Graphic Services  

The Line W moorings are like oceanic tollbooths. But instead of collecting a fee, they are measuring the strength and properties of the Deep Western Boundary Current as it flows past.

Line W is a way to observe and document changes in the current, which may be linked to changes in global heat transport. Such observations may give us insights into how Earth’s changing climate is affecting the ocean, and vice versa.

Detour at the Grand Banks
On the theoretical large-scale model conceived by Stommel and Arons, the Deep Western Boundary Current is the main oceanic highway directing cold, dense water southward in the North Atlantic—much the way Interstate 95 steers traffic on the U.S. Eastern Seaboard.

But the real ocean is far more complex. It is full of sharp curves and detours—underwater mountains, continents that jut out, and swirling eddies, all of which can divert water out of the Deep Western Boundary Current. If that water were cars, we might not be counting all the cars heading south at the Line W tollbooths; the measurements at Line W may not be telling us the full story.

   WHOI Graphic Services  

In the last decade, scientists Amy Bower of WHOI and Susan Lozier of Duke University have been using floats to track the southward flow of deep water from the North Atlantic. They have observed that many floats seem to get off the Deep Western Boundary Current highway.

One potential detour spot may be at the Grand Banks of Newfoundland, where the coastline takes a series of sharp turns. Something may be happening at this juncture that affects the watery traffic downstream, and that’s what I am trying to figure out.

Back to fundamentals
So I am taking a page from Stommel and Arons’ book. I am proposing to strip the problem down to its essential elements. I hypothesize that water leaves the Deep Western Boundary Current at the Grand Banks because of two primary features.

The first feature is the bend in the coastline. The current could have trouble rounding the curve and in response, create eddies that spin out and carry water away from the current.

The bend also directs the Deep Western Boundary Current close to the other key feature: the Gulf Stream-North Atlantic Current system, which flows near the surface above the Deep Western Boundary Current at ten times the speed.

The energetic Gulf Stream spins up many eddies that can peel off northward into the Grand Banks region. These eddies of Gulf Stream water may collide and mix with waters in the Deep Western Boundary Current, changing their salinity, temperature, and density, and causing some water to leak out of the boundary current.

Manipulating my model ocean

   WHOI Graphic Services  

I am creating a mathematical model that focuses on just the three components that I think matter most: the Deep Western Boundary Current, the bump in the coastline that affects it, and the Gulf Stream. The model is made up of two layers, with the Deep Western Boundary Current in the lower layer and the Gulf Stream in the upper layer.

The equations in the model simulate the dynamics of the ocean and generate eddies in my idealized ocean off Newfoundland where the currents are influenced by the topography. I conduct numerical experiments by manipulating the strengths and configurations of the three key components and seeing what effects these manipulations produce. Over time, I should be able to tease apart why water is diverted from the Deep Western Boundary Current.

Once we have a better understanding of these places where water leaves the current, we can apply that knowledge to refine our measurements of oceanic heat transport. And then we can turn to the bigger questions: How do these diversions from the Deep Western Boundary Current affect the global transport of heat? What impacts could Earth’s changing climate have on the ocean’s interglobal current system? And how could that, in turn, cause further changes in our planet’s climate?

This research was funded by the National Science Foundation.


by Isabela Le Bras/Sail-World


  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=120126

12:37 AM Sat 15 Mar 2014GMT


Click here for printer friendly version
Click here to send us feedback or comments about this story.







Sail-World Cruising News - local and the World

New Holiday Camps at Lake Macquarie with the H2O Sports Academy by H2O Sports Academy Australia, Lake Macquarie, NSW
he H2O Sports Academy Australia opened its doors to the first group of kids aged between 6 and 17 years for the first H2O Holiday Camp 12-19 January. Based within the impressive NSW Sport and Recreation Centre at Point Wolstoncroft on Lake Macquarie. ... [more]  

Oceans of Hope, the 67-foot yacht undertaking the first circumnavigation with a working crew of people living with multiple sclerosis (MS), spent the weekend traveling the locks of the Panama Canal. They have arrived in Panama City greeted by the Pacific Ocean and chocked off another major milestone in circling the globe under sail. ... [more]  

Planning an open ocean cruise? If so, you are the key to helping scientists better understand the health of the world’s oceans. When we look across the limitless horizon of a vast ocean, it’s easy to believe that one little action can’t possibly hurt or help something so large as the world’s oceans. ... [more]  

The hideous, mildly terrifying and rarely sighted frilled shark has turned up in waters off south-eastern Australia. The species, whose ancestry dates back 80 million years, is known as the 'living fossil'. ... [more]  

Croatia First Regatta - Positioned between a grand prix overseas regatta and a cruising rally is a brand new limited entry one design event due to start from the town of Split in Croatia on June 13, 2015. ... [more]  

Bay of Islands Sailing Week - BOISW and the New Zealand Millennium Cup start Wednesday and Doyle Sails are offering an overnight service on sail repairs and a basic rigging service. Doyles have team members on several boats during the regatta, so will be ready to help you as soon as you hit the dock, should you suffer any damage during the racing. ... [more]  

World Arc Leg 2 has commenced. After a very enjoyable and entertaining week here in Santa Marta it is with fond memories that the fleet depart for the islands of San Blas today. Santa Marta have been generous hosts to World ARC and World Cruising Club look forward to returning in 2016. ... [more]  

2014/15 World ARC - Crossing their final ocean, today Chika-Lu and Nexus were the first of the fleet to arrive on the quaint island of St Helena. Located in the South Atlantic, they have sailed approximately 1700nm to reach this remote British colony from Cape Town, South Africa. ... [more]  

Multihull Solutions has kicked off the new year with the launch of an impressive new website at www.multihullsolutions.com.au. The company, which has become the Asia Pacific’s leading multihull specialist, developed the new site as an informative resource for those looking to buy, sell or research catamarans and trimarans. ... [more]  

2014 warmest year since records began + Video by NOAA National Climatic Data Center
The year 2014 was the warmest year across global land and ocean surfaces since records began in 1880. The annually-averaged temperature was 0.69°C (1.24°F) above the 20th century average of 13.9°C (57.0°F), easily breaking the previous records of 2005 and 2010 by 0.04°C (0.07°F). ... [more]  

In what should have been a leisurely cruise home to Coffs Harbour from Sydney with a newly acquired yacht, a mechanical failure off Hat Head south of Trial Bay last night, meant the skipper and two companions on the vessel needed help. ... [more]  

A newly awakened volcano off an uninhabited Tongan island has finally been viewed up close, with volcanologists saying it has created a substantial new island since it began erupting last month. ... [more]  

This spring, the first ocean-going full-rigged ship to be built in America in over a century will begin sailing, and teens from around the country and the world will board in July and August for thrilling one- and two-week Education at Sea camps. The 200-foot Sailing School Vessel (SSV) Oliver Hazard Perry has a 500-ton steel hull and a 130-foot tall rig with square sails on all three masts. ... [more]  

Highland Yacht Club - Lake Ontario’s hidden jewel of a Yacht Club by Katherine Stone - Canadian Yachting Magazine
Nestled in the middle and protected on all sides you will find one of the friendliest places on Lake Ontario, Highland Yacht Club. The City of Toronto put an ad out, some 40 years ago to encourage people to come together to form and build a boating community at the base of these Bluffs. What emerged were four clubs and Bluffer’s Park Marina. ... [more]  

Particular Harbour – Gananoque by Andy Adams - Canadian Yachting Magazine
Andy says, 'I know of no other boating location quite like the town of Gananoque in the Thousand Islands. The graceful double-ended St. Lawrence rowing skiffs were a swift and effective way to travel through the area in the 1800s carrying cottagers to their islands, visiting millionaires to the fishing grounds and transporting all manner of goods through the beautiful and sheltered island area.' ... [more]  

SE Asia tanker hijacks rose in 2014 - IMB report reveals by International Chamber Of Commerce
Attacks against small tankers off South East Asia’s coasts caused a rise in global ship hijackings, up to 21 in 2014 from 12 in 2013, despite piracy at sea falling to its lowest level in eight years, the International Chamber of Commerce (ICC) International Maritime Bureau (IMB) has revealed. Pirates took 442 crewmembers hostage, compared with 304 in 2013. ... [more]  

'It was great to see Ben Ainslie sailing past Necker Island as he enjoyed his honeymoon with his delightful new wife Georgie Thompson. Seeing as Ben is one of the greatest sailors of all time, what we didn’t expect to see was his boat getting into trouble!' said Richard Branson. ... [more]  

Christmas Caribbean Rally 2014 successful end (CCR 2014) sees elated crews and their shore support teams enjoying Antigua to the full. Eight boats and almost 50 crew safely completed the 2850nm crossing from Marina Rubicon in Lanzarote to arrive in the historic Caribbean sailing capital of Nelson’s Dockyard in Antigua. ... [more]  

The last thing anyone thinks when looking at single-handed sailors in the Vendée Globe non-stop round the world race is that this might be comfortable and relaxing. However, combining the fastest possible yacht design with the demands of cruising is in vogue. ... [more]  

10th January marked a special day in World ARC history as two fleets set sail as part of new annual editions of World Cruising Club's round-the-world rally. In the rally's Caribbean home port of Saint Lucia, the World ARC 2015-16 fleet began their 15-month circumnavigation, whilst in South Africa the seasoned adventurers of the World ARC 2014-15 fleet re-started after a two month break. ... [more]  

Corals strive to stay just under the surface of the ocean. Coral reefs need to get it just right—submerged in the sea, but shallow enough for the corals’ symbiotic photosynthetic algae to soak up sunlight. Too deep and the ecosystem wastes away without solar energy to make food. Too shallow and corals dry out at low tide. This delicate balance is achieved by a constant tug-of-war. ... [more]  

The lowering of the ocean’s pH is making it harder for corals to grow their skeletons and easier for bioeroding organisms to tear them down. Erosion rates increase tenfold in areas where corals are also exposed to high levels of nutrients, according to a study published January 2015 in the journal Geology. ... [more]  

An Australian yachtsman who lost a treasured boat at sea has described his rescue off a remote Indonesian tropical island as a 'sweet and sour experience'. ... [more]  

Recently we asked a group of around 100 cruisers if they’d be interested in a rally with a greater emphasis on the sailing side of both passage making and cruising. ... [more]  

Already renowned for state of the art facilities and luxury conveniences, Abell Point Marina is about to add two more exceptional guest services to its bow – a free courtesy car and a dedicated helicopter service. Responding to feedback from guests, the Marina has added the new services in order to help provide the best possible experience for visitors to the area. ... [more]  

The Hoegh Osaka ran aground in the Solent off the coast of the Isle of Wight late on Saturday and is listing at 45 degrees on Bramble Bank. The salvage master tasked with refloating the Costa Concordia cruise liner, Capt Nicholas Sloane, said salvors face a 'critical situation'. He said the next 24 hours are 'crucial for the local conditions and the wash'. ... [more]  

A new study by researchers at Woods Hole Oceanographic Institution and their colleagues examined behavioral responses to sound by cuttlefish, a type of shell-less mollusk related to squid and octopi. The study is the first to identify the acoustic range and minimum sound sensitivity in these animals. ... [more]  

When we started our Great Loop journey last year, we did something that hadn't been done before - capture the entire Great Loop on video. We mounted a GoPro camera on our flybridge and shot high-def, time-lapse video through every travel day. Here are some of favorite videos. ... [more]  

World ARC 2014 - One year on by World Cruising Club
For the World ARC 2014 fleet January 2015 marks a significant milestone. Exactly one year on since their voyage began in Saint Lucia, they have been on an adventure exploring the spectacles of the Pacific and Indian Oceans. Now, with the fleet moored at the V&A Waterfront in Cape Town it’s almost time to once again set sail and get back on the ocean. ... [more]  

Radio Ham Exams in the Davao Gulf of the Philippines by Seven Seas Cruising Association
On February 25, 2015 at 0930 local time the Seven Seas Cruising Association (SSCA) is conducting a ham exam 'gam' at Holiday Oceanview Marina on Samal Island in the Davao Gulf of the Philippines. ... [more]  

This summer the Australian National Maritime Museum is all about underwater exploration with its brand new children’s adventureland, Voyage to the Deep. And to celebrate it is inviting families to a special submarine family fun day inspired by the exhibition and its resident submarine HMAS Onslow on Sunday 18 January. ... [more]  

This summer the Australian National Maritime Museum invites families to enjoy a brand new theatre show, Captain Nemo’s Nautilus, inspired by its new children’s adventureland, Voyage to the Deep. ... [more]  

It was an epic battle right from the starter’s gun with Comanche, the new and very sexy US built 100-foot supermaxi, leading the 2014 Rolex Sydney Hobart Yacht Race fleet out of the heads in record making speed. ... [more]  

Man escapes burning yacht on Shoalhaven River
Toronto Boat Show Ocean Sailing Forum - Learn from cruising experts
World ARC 2015-16 fleet prepare in Cape Town
Five sailing rope tips for sailing or cruising
Marine Rescue Kioloa and Ulladulla vessels investigate flare sighting
Phuket International Boat Show preview
Two men and 4-year-old missing on fishing trip off Jervis Bay
Rolex Sydney Hobart Yacht Race - Age no barrier for the final finisher
Rolex Sydney Hobart - Friends make Wild Rose 'Simply the Best'
Wish a Marine Rescue NSW volunteer a happy New Year on Sydney Harbour
Rolex Sydney Hobart; Wild Action on Handicap Winning Wild Rose VIDEO *Feature
Stop thief! Spies nab Spy thieves
Stop thief! Spies nab Spy thieves
10 'New Year habits' for safe and enjoyable boating
Old charts and inexperience brings yacht undone
The power of the tide
Bringing a Lab to seafloor - New device probes deep-sea microbial life
For Christmas a Shiny new Sail-World.com *Feature
Marine Rescue Batemans Bay brings two home safe on Christmas Eve
ARC 2014 – 29th Atlantic Rally for Cruisers wraps up in Saint Lucia
Yachties forbidden cargo 'deliberately hidden' claims NZ officials   
Quiet Atlantic hurricane season - new surge forecast products debuted   
Beach party wraps up ARC+ for another year   
Waves within waves   
Nereid Under Ice vehicle: A powerful new tool for polar science   
2015 Lakefest Aquatic Week - A week-long celebration of boating   
Marine Auctions raises the bar with live internet bidding for auctions   
Christmas Caribbean Rally 2014 - Atlantic adventures underway   
You are what you eat – if you’re a coral reef fish   
Sea urchins from Antarctica show adaptation to ocean acidification   
Seabird poo has unique spectral signature - satellite images show   
Keep safe on the water this holiday season   
Sail-World new format - Important first visit changes needed   
Farewell to Knorr: Research ship and crew made oceanographic history   
Antarctica Day 2014: 55 years since signing of the Antarctic Treaty   
Scientists urge protection of world's deltas   
Court tells France to pay damages to Somali pirates   
Yacht lost on Majuro   
Skipper's 'top ten' checklist for safer sailing   
Go on an underwater adventure this summer at the museum   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph, contact the photographer directly.
XLXL NEW Cru SH
LocalAds   DE  ES  FR  IT