sail-world.com
 
 
News Home Cruising Photo Gallery Video Gallery
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.







News - USA and the World

In a lot of ways, it was kind of befitting that the best conditions of the last day of the Sailing World Cup – Melbourne, were saved for the Women’s Laser Radial Medal Race. Apart from highlighting them in glorious sunshine, like Huey’s own spotlights, it also brought into frame that were only two girls 470 crews in attendance for the regatta. ... [more]  

RORC Transatlantic: As with every yacht participating in the race, staff from Camper & Nicholsons Port Louis Marina greeted the French team on arrival with warm congratulations, a cold beer and a welcome basket from the Grenadian Tourism Association on behalf of the people of Grenada. The crew of five looked tired after nearly 17 days at sea, but owner, Frank Lang was full of praise for his crew. ... [more]  

2014 Rolex Sydney Hobart Yacht Race - Perpetual Loyal is no stranger to the Rolex Sydney Hobart. Winning line honours in 2011, they have continued to be a contender, especially in heavier breezes. ... [more]  

The website for the 2015 Finn Gold Cup in Takapuna, New Zealand, has been launched. The Finn class is eagerly anticipating a return to Takapuna Boating Club for what will be only the second Finn World Championship to be held in New Zealand. It will have been 35 years since Cam Lewis (USA) beat John Bertrand (USA) in a thrilling final race showdown in 1980, to take the Gold Cup. ... [more]  

Looking for a great Christmas present which you can buy with a few mouse clicks? Bob Fisher's books on the Round the World races, Farr 40's and the definitive America's Cup two volume set are still available, along with other titles from South Atlantic Publishing. ... [more]  

Clipper Round the World Yacht Race - In January Nqoba, from Durban, will embark on his Yachtmaster qualification and will have none other than legendary sailor Sir Robin Knox-Johnston, the first man to ever sail solo, non-stop round the world in 1968-69, as his mentor as he takes the first steps to realise his dream of circumnavigating the globe at the helm of a Clipper 70. ... [more]  

IFDS 2014 Worlds: But as you reflect back on the year, we hope you will agree that week of competition in Halifax, Nova Scotia set a new standard for disabled sailing. It was the largest world regatta yet with 18 SKUD-18 teams, 14 Sonar teams and 49 2.4mR competitors and the largest number of countries participating. There were some challenging days finding enough wind to race. ... [more]  

The 2015 McDougall + McConaghy Moth World Championship is set to be even more of a spectacle this year, with the return of the Zhik ‘Mothapolooza’ which promises a potential head-to-head with teams of America’s Cup and Olympic sailors. ... [more]  

Volvo Ocean Race: Chris Nicholson Interview - Part 2 - On the Rocks *Feature by Richard Gladwell/Sail-World.com/nz, Auckland, NZ
Part 2 of three part, 80 minute, interview with Team Vestas Wind skipper, Chris Nicholson on the wrecking of the Volvo Ocean Race yacht on an idyllic atoll in the South Indian Ocean during the night of November 29. In this part, Nicholson covers what happened from the time the Volvo65 hit the reef on the SE corner of the Cargados Carajos Shoals. ... [more]  

Last Saturday saw the third annual St. Maarten Regatta Beach Clean-Up organized by the St. Maarten Regatta as part of the Regatta Art Competition. Unfortunately, due to exams, not many children showed up. ... [more]  

US Sailing’s Olympic Sailing Committee (OSC) has released the selection procedures for the 2016 U.S. Olympic Team (Sailing) in the 10 events selected for the Rio de Janeiro 2016 Olympic Games. The Games of the XXXI Olympiad will take place from August 5-21, 2016, and the sailing events will be based at Marina de Gloria on Rio de Janeiro’s harbor front. ... [more]  

2014 Rolex Sydney Hobart Yacht Race - When the cannon fires sending the 118 entries on their way in the Cruising Yacht Club of Australia’s 70th Sydney Hobart Yacht Race on December 26, two yachts will stand out, because they first competed back in the early days of the race. ... [more]  

Volvo Ocean Race have announced from their headquarters in Alicante, Spain that an independent report has been commissioned into the grounding of Team Vestas Wind’s boat on a reef in the Indian Ocean. The report will be released during the Auckland stopover. ... [more]  

The French sailor scratches his newly shaved skin. He tentatively reaches towards a plate of fried chicken pieces. Still not sure. He rubs his chin again. He hesitates. Laurent briefly runs his eye over the other plates, but finally he can no longer resist the crispy fried chicken pieces. 'This is what I’ve been waiting for,' says the cheerful Frenchman. ... [more]  

Transatlantic Race: After time correction, Apollo 7 is leading IRC Two. Nigel's team included three close friends from his home town of Plymouth, Devon: Steve Wassell, James Slater and Mark Davies. Also on board were two offshore specialists: Dan Gohl, a past Class40 world champion and Sevenstar Round Britain and Ireland Record holder as well as Rolex Fastnet Race winner Brett Aarons. ... [more]  

The 2014 OK Dinghy World Championship opens at Black Rock Yacht Club on Port Phillip Bay in Melbourne, Australia, on December 28th and so far there are around 80 entries, with perhaps a few more before registration closes. This 52nd OK Dinghy World Championship will be the third time that Black Rock YC has hosted the event, following 1982 and 1990. ... [more]  

Adelaide Sailing Club played host once again to the Melges 24 class for its 'Christmas Sprint Series', the third three day M24 regatta in five weeks held by ASC which, (in the same season the club is also hosting the M24 Australian Championship) says something about the power of persuasion, energy and organisation being put in to M24 class by its Australian Secretary Donna Evans. ... [more]  

The team, led by Jerome Clerc, will not compete on the 2015 Extreme circuit but intends instead to focus entirely on the Decision 35 Vulcain Trophy season in Switzerland. The professional sailing squad onboard Realteam capped a superb 2014 season with a third place in Sydney last weekend that put them on the third step of the overall Extreme Sailing Series Championship podium. ... [more]  

Volvo Ocean Race: Chris Nicholson on the Team Vestas Wind disaster - 1 *Feature by Richard Gladwell, Sail-World.com/nz, Auckland, NZ
Part 1 of three part interview with Team Vestas Wind skipper, Chris Nicholson on the wrecking of the Volvo Ocean Race yacht on an idyllic atoll in the South Indian Ocean during the night of November 29. In this part, Nicholson discusses the factors leading up to hitting the reef, interspersed with other research information, charts, video and images. Parts 2 and 3 will follow on consecutive days. ... [more]  

USA 4 Windsurfing campaign by USA 4 Windsurfing Campaign
Change is inevitable. No matter how hard you try to keep things the same, there comes a time when you must move on. The harder you resist, the more difficult the change. ... [more]  

2014 Rolex Sydney Hobart Yacht Race - Bob Oatley’s Rolex Sydney Hobart race record holder, Wild Oats XI, is out of the water for a final modification after a high speed and rough weather training run off Sydney. ... [more]  

This is Peter Perfect in the Turbo Terrific from the 60s cartoon series, the Wacky Races. Of course, to Australians and a plethora of motoring enthusiasts the world over, the real life Peter Perfect will always be The King of The Mountain. RIP Brocky (Peter Geoffrey Brock). ... [more]  

RORC Transatlantic Race 2014: The Spirit of Adventure crew of 15 were met dockside by representatives of the Royal Ocean Racing Club and well wishers at Camper & Nicholsons Port Louis Marina. After enjoying an ice cold beer, the first cold drink for two weeks, the crew cleared customs and headed for the Victory Bar for eggs and bacon. ... [more]  

ISAF World Sailing Rankings - 15 December 2014 - The World Cup Final was a 100-point regatta and whilst Shaw took maximum points, Tartaglini’s eighth was enough for her to hold on to World number one heading into 2015. Shaw remains at World number two with Laura Linares (ITA) at World number three and 2014 World Champion Charline Picon (FRA) at World number four. ... [more]  

Comanche; Supermaxi Showdown VIDEO by Dale Lorimer, Sydney
In what is touted to be one of the most hotly contested Rolex Sydney Hobart line honours battles in recent history, there's been plenty of on-water supermaxi activity over the last week. ... [more]  

Commodores Cup - There was barely four knots of wind for the start of race one today. Brian and I started in port tack, at the committee boat, hit the right corner, and never looked back. There were a few tricky moments on the first run, in four knots of wind, but we managed our position well. For the second lap, the breeze built to six knots and steadied out a bit which made out lives easier. ... [more]  

2014 /2015 International Audi Melges 20 Miami Winter Series - Event No. 1 - One final light air race concluded the 2014/15 Audi Melges 20 Miami Winter Series Act No. 1 on Sunday, hosted by Coconut Grove Sailing Club (CGSC) with championship winner Jason Michas on Midnight Blue along with tactician Mark Mendelblatt and crew Trevor Moore winning the final heat and taking the overall win. ... [more]  

2014 RORC Transatlantic Race - Aref Lahham's Swan 68, Yacana crossed the finish line of the RORC Transatlantic Race on Sunday 14th December at 03:25 UTC. The crew are all friends from Greece and the German Frers designed yacht with classic lines is beautifully maintained and balanced for a heavy displacement yacht. ... [more]  

2014 Extreme Sailing Series - Act 8 - The Wave, Muscat’s long tenure of the Extreme Sailing Series crown came to an end in Sydney today when Swiss team Alinghi won the eighth and final Act of the year to take an overall victory in the 2014 series despite a superb late challenge from Tom Slingsby on Oman Air. ... [more]  

Images of the Extreme Sailing Series, Act 8, Sydney, Australia and video about most memorable in the Series' eight-year history. The Series was won by Alinghi after an action packed three days of racing on the confines of Sydney Harbour, which was the venue for the international series for the first time. ... [more]  

In this case it was the 5,220-nautical mile stage from Cape Town to Abu Dhabi – the second stage of this year’s Volvo – that took the crew on the China-sponsored entry Dongfeng Race Team just under 24 days to complete. But the striking thing about the men on board Dongfeng is that all of them were finding it very hard to think of anything except the final few hours. ... [more]  

Larson’s words say it all: 'We’ve had an amazing season with an amazing team. To win the season and the Act on the last day in the conditions we had here in Sydney, which is the best sailing venue in the world, is a special moment that’s going to take a long time to sink in.' ... [more]  

Extreme Sailing Series: Oman Air’s Tom Slingsby (AUS) was awarded the trophy for showcasing the greatest tactical performance and improvement seen this year on a debut appearance at the Extreme Sailing Series™. Series Main Partner, Land Rover presents the Award to teams or individuals in recognition of those who have demonstrated the finest examples of skill, sportsmanship and strength of mind. ... [more]  

ISAF Sailing World Cup Melbourne - Medal Race Images
Extreme Sailing Series: Alinghi dons ESS Crown, Oman Air wins award
18ft Skiffs: Rooklyn scores win in Syd. Barnett Jr. Memorial Trophy
ISAF Sailing World Cup: Fan cranks up for final Melbourne day + Videos
Miami Star Winter Series - Commodores Cup Day 1
Extreme Sailing Series: Delayed coverage - Day 4 +Audio *Feature
Volvo Ocean Race - Dongfeng score another excellent result
Audi Melges 20 Miami Winter Series - Fleet rumbles in Miami
Extreme Sailing Series - The Wave, Muscat see championship bid slip
2014 RORC Transatlantic Race - From acorns grow oaks
Volvo Ocean Race - Team Brunel (NED) wins Leg 2
2014 RORC Transatlantic Race - Oakcliff Ocean Racing Team wins
Extreme Sailing Series: Day 3 image gallery from Sydney Harbour *Feature
The Extreme Sailing Series™ - Action-packed day on Sydney Harbour
Early Christmas presents for ISAF Sailing World Cup medallists + Video
Volvo Ocean Race: Leg 2 finish - Team Brunel wins from Dongfeng *Feature
Audi Melges 20 Miami Winter Series - Day 1 overall
2014/2015 Audi Melges 20 Miami Winter Series - Images by Joy Dunigan
Extreme Sailing Series: Live coverage - Day 3 +Audio *Feature
St. Maarten Heineken Regatta kicks off with successful sponsor party
Successful seventh edition of 2014 World Yacht Racing Forum   
2014 Star Sailors League Finals - Catching up with Robert Stanjek   
2014 ISAF Sailing World Cup - Melbourne - Day 6 Preview   
Extreme Sailing Series - Act 8 Photos and season highs and lows video   
Volvo Ocean Race 2014-15 Leg Two - Final fight to the finish + Video   
Extreme Sailing Series Act 8 - McMillan tops table in Sydney + Video   
Anna Tunnicliffe: Alinghi - Day 2: Extreme Sailing Series, Sydney   
ISAF SWC Melbourne - Top ten prepare for Port Phillip showdown + Video   
Extreme Sailing Series Act Eight 2014 – Photos by Andrea Francolini   
Volvo Ocean Race: Three way alley-brawl on final day of Leg 2 *Feature   
International Audi Melges 20 Miami Winter Series 2014-15: Holiday heat   
ISAF SWC Melbourne: Family affair for Papua New Guinea sailors + Video   
Australian 18 Footers League Club Championship - Stormy capsize   
RORC Transatlantic Race - Lupa spice it up for Line Honours victory   
Extreme Sailing Series: Replay coverage - Day 2 +Audio *Feature   
America's Cup: Oracle crew member's penalty for cheating is reduced *Feature   
US Tour: Four GC32s to compete at Quantum Key West Race Week + Video   
Extreme Sailing Series Act 8 - Wet, wild and windy   
ISAF Sailing World Cup - Thrilling action on Day 4 + Videos   
ISAF Sailing World Cup Melbourne day four - Extreme sailing   


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 US
LocalAds   DE  ES  FR  IT