sail-world.com
 
 
News Home Cruising Australia Cruising USA Cruising Canada Boats for Sale Sail-World Racing Photo Gallery FishingBoating
Video Gallery Newsletters
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

1:37 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

The World ARC fleet departed the Cocos (Keeling) Islands this morning, embarking on the second longest sail of their circumnavigation; a 2350 nautical miles journey to Mauritius. Their stay in the tropical atoll has certainly been one to remember. ... [more]  

A port operator has today (Monday 29 September) pleaded guilty to health and safety breaches, following the deaths of three crew members of a tug which capsized on the River Clyde in 2007. Clydeport Operations Ltd, who were sentenced at the High Court in Edinburgh, received fines totalling £650,000. ... [more]  

Pantaenius, the world’s leading specialist yacht insurance company, has been at the forefront of yacht insurance for more than 40 years, earning a reputation for transparency and commitment to customer service that provides round-the-clock international support and reliable, speedy claims settlement. ... [more]  

World-wide the development of marine wind farms will grow. Britain's RYA is taking a proactive stance that can serve as an example for other yachting bodies. If wind farms could be an issue in your waters, its important to follow just what is happening in GBR. Speaking today Stuart Carruthers, RYA Cruising Manager said 'The RYA will now be responding to those of the Panel’s questions that have bee ... [more]  

How to make a distance scale for faster navigation by Captain John Jamieson, Florida
If you are anything like me, sailing navigation can be a challenge when short- or single-handed sailing. But you still need to be able to plot fast and accurate positions for sailing safety. Here one little-known sailing tip used by the pros that will help you do just that! ... [more]  

The 14th edition of the Atlas also includes a new double page map of the Arctic Ocean, which highlights the dramatic long-term decline of Arctic sea ice cover. The sub-ice maps draw on bedrock data, provided by the British Antarctic Survey, to show physical features which are obscured by ice cover. ... [more]  

Royal National Lifeboat Institution (RNLI) volunteer crews from Flamborough and Bridlington launched the afternoon of Tuesday, 16 September, after a helicopter crashed close to Flamborough Head. Flamborough RNLI’s Atlantic 85 inshore lifeboat launched at 1.45pm, followed soon after by Bridlington RNLI all-weather lifeboat. ... [more]  

On Monday 22 September the EU Naval Force flagship, ITS Andrea Doria, met the Chinese Navy ship, CNS Changbaishan, in the Gulf of Aden. ... [more]  

The Presque Isle peninsula is a 3,200-acre – 7-mile long arm that extends northeast into Lake Erie creating a large, sheltered boating paradise of a harbour. With a string of well equipped marinas, a wealth of facilities and a very impressive yacht club, it has attractions for boaters that place it at the top of a cruising destination list. ... [more]  

Iridium have recently released the Iridium GO!, their latest product in the satellite communication market. It’s portable, battery powered, and creates a WiFi hotspot. www.predictwind.com!PredictWind!new have partnered with Iridium to put together a package catering specifically to the marine market. ... [more]  

In the early morning of Friday 19 September, EU Naval Force frigate, ESPS Navarra, came to the aid of a stricken yacht in the Gulf of Aden. The yacht had been detected on the warship’s radar in the early morning. ESPS Navarra’s Bridge team initially tried to hail the yacht via their VHF radio. ... [more]  

As their annual migration south approaches, sail and powerboat cruisers are stocking their boat’s lockers, checking systems and taking inventory of spare parts. But that’s not the only preparation these cruising 'snowbirds' will need to do, says Boat Owners Association of The United States (BoatUS). ... [more]  

Lost your rudder at sea? Michael Keyworth perfected a way to steer using drogues. To engineer this solution, he removed the rudder from his own boat(!), and experimented with different method, and has summarized his technique in this terrific article. ... [more]  

You scratched my seagrass! by Steven Katona, Newport, RI
Sailors for the Sea publishes monthly articles that translate the language of marine science into fascinating articles about ocean health. ... [more]  

Following a relatively short stopover in Christmas Island, eleven of the World ARC fleet have now arrived in their next paradise, the Cocos (Keeling) Islands. From first settlement in 1826 by English merchant Alexander Hare, through decades of administration by the Clunies-Ross dynasty, most island inhabitants had little freedom or contact with the outside world. ... [more]  

Paul Whitehouse and Simone Wood, from Wolverhampton and London, were in La Paz in Baja California when Hurricane Odile hit the Baja California peninsula last Sunday. It is thought their yacht overturned, and the couple have not been seen since. The couple is thought to have been living in La Paz for around a year. Mr Whitehouse is believed to be a scuba diving instructor in the city. ... [more]  

This might be the Texting and Facebook generation but boaters need to use VHF radio says volunteer rescuers from Weston-super-Mare's lifeboat station who rescued a yachtsman whose boat sank in the middle of the Bristol Channel and who then texted his girlfriend. ... [more]  

Earlier this year two men died in their bunks of carbon monoxide poisoning caused by the highly toxic fumes given off from a poorly maintained butane gas cooker. The cooker which was located in the wheelhouse had been lit to heat the wheelhouse and sleeping area. A carbon monoxide alarm was not fitted. ... [more]  

The Arctic is an ocean surrounded by land and Arctic sea ice is the thin layer of frozen ocean water that forms and grows during the winter, and melts in the summer. Dr Jeremy Wilkinson from the British Antarctic Survey provides a scientist’s perspective on the trend for decreasing Arctic sea ice. ... [more]  

The Virgin Islands are an archipelago. That part, which is a British overseas territory, is commonly referred to as the BVI. About 30,000 people live in the BVI, most of which live on the island of Tortola. The BVI are comprised of about 50 islands the majority of which are not inhabited by humans. ... [more]  

Visitors to this year’s his year's Genoa International Boat Show will find the event 'renewed and more dynamic', adapting to the needs of an industry that is just beginning to see Spring at the end of a long hard Winter. Exhibitor numbers are up on last year, with sailing boats and small-to-medium sized motor boats leading the charge. The show will have a new layout ... [more]  

The Galley Guys take on the Vancouver International Boat Show by Greg Nicoll with Frank Leffelaar and Friends
The Galley Guys hit the Vancouver International Boat Show running. All day long, we were checking out new boats, looking into ice lockers, peeking into storage compartments, seeing what’s new for gourmet cooking onboard and being forced to live on 'show food' by day. ... [more]  

Are you ready to enter that marina? by Captain John Jamieson, Florida
Are you ready to enter that narrow canal or passage ahead that leads into the marina? Have you prepared your boat and crew for the unexpected? No matter if it's a brand new marina or the one you use as 'home base', docking preps will be the same each and every time. ... [more]  

Each summer, in a Canadian cruising tradition, thousands of Western Lake Ontario sailors join the annual summer migration to the Bay of Quinte and the Thousand Islands. ... [more]  

The RYA is working to improve its understanding of the number and spread of leisure boaters either using or not using AIS on board their vessels, in order to quality assure our data as we update the RYA’s Coastal Atlas of Recreational Boating. ... [more]  

Unlike an automobile, recreational boats have special safety needs when it comes to refueling. Stern drive or inboard powered boats have closed engine compartments where volatile gasoline vapors don’t easily dissipate, and older gasoline powered boats are the riskiest to refuel as their brittle fuel hoses can crack, leaving gas in the bilge after a fill-up. ... [more]  

For the next 72 hours the majority of the World ARC fleet will be moored in Flying Fish Cove on Christmas Island. The crews will have been planning their 48 hours stopover here before leaving Bali so they can make the most of it. Christmas Island is one of the jewels of the Indian Ocean and has a lot to offer. 63% of its land mass is made of National Park which is home to many endemic species. ... [more]  

Three-time President of French Polynesia, Gaston Tong Sang, and current mayor of Bora Bora, has written a strong letter of support for the Blue Planet Odyssey, assuring the fleet a warm Polynesian welcome when they arrive there in 2015. ... [more]  

Do you want to win a trip of a life time to any port of call along the Round the World Race in 2015? Great, because it is simple! All you have to do is design, scribble, write or draw a T-Shirt design and submit it online at www.ecsix.com/contest. 'You don’t have to be a designer to win, we are after the best creative idea that fits our brand' says ECsix’s Scott Vogel. ... [more]  

Remember to properly dispose of obsolete distress beacons by Australian Maritime Safety Authority
You might not be 'down under but here is a cautionary tale!- The Australian Maritime Safety Authority (AMSA) is urging people to ensure they dispose of their obsolete and unwanted distress beacons correctly after emergency services spent more than six hours homing a beacon eventually found dumped in bushland on Queensland's Sunshine Coast over the weekend of 6-7 September. ... [more]  

Blue Planet Odyssey - We made landfall the morning of Saturday, September 13th at 0900 local time as we passed Race Point at the entrance into Cape Cod Bay. Since leaving St John’s less than one week ago we had covered 1109 miles, at an average of just under seven knots. ... [more]  

The World ARC fleet made a great sight on September 14th as they sailed across the start line at the entrance to Benoa Harbour, Bali. Before leaving Bali International Marina, Arsa, a tour guide who had looked after the fleet during their week-long stay, visited yachts to perform a traditional Hindu blessing. It was a beautiful way to send off the fleet and a very special moment for many. ... [more]  

An international team of scientists, including the British Antarctic Survey, studied the geologic history of the area of the Antarctic Peninsula where the Larsen B ice shelf disintegrated, the portion of Antarctica that extends northwards toward South America. The new findings support the idea that such a dramatic collapse can be caused by surface warming. ... [more]  

Baltic 4 Nations - Next edition sets sail July 2015
BoatUS offers 'Boater's Guide To Winterizing'
Yachts prepare for second Atlantic Odyssey, departing this November
Thai drama with Phuket yacht clampdown
Marine Rescue volunteers in two searches on NSW northern waters
Sailing Rallies launch two new events at PSP Southampton Boat Show
World ARC crews in Bali
Could your sailing navigation use a tune-up?
Images of marine sunsets by Tripadvisor
Citizen science model proposed to fill fundamental ocean data gap
Africa-Europe Challenge - Three short harbor races to be organized
European Odyssey - Sardinhada in Lisbon for the fleet
Ocean Cruising Club celebrates 60th Anniversary with record gatherings
The Boat Cookbook
La Grace - Flagship of Africa-Europe Challenge in 2014
Indian Ocean-wide tsunami exercise to test readiness
Blue Planet Odyssey - Aventura makes landfall at St John’s
18 anti-piracy weapons for ships to fight pirates
World ARC fleet now arriving in Bali
Governor’s Cup Yacht race - Great for cruisers and racers alike
Cowes Breakwater causes new tidal flow   
EU Naval flagship- frigate assist yacht twice maydays in pirate zone   
An offer a Galley Guy cannot refuse   
Dinghy Safety - More to think about   
World ARC fleet to enter Indian Ocean for the first time   
What can you do to prevent electrocution and ESD?   
Pack this sailing gear for 'hands-free' lighting   
Salty Dawg Rally Seminar Series planned October 8 in Annapolis   
Europe tightens up on skippers competency certification   
World ARC fleet departs Darwin under full sail   
NOAA expedition discovers ship’s timepiece silent for nearly 200 years   
Blue Planet Odyssey - Northwest Passage gate opens   
A Cruising Guide to the Dominican Republic 6.0 now available   
BNS Leopold I to commence counter-piracy operations   
Africa Europe Challenge introduces 'Spectator's Package'   
Wanted youth circumnavigators on a 'Voyage of Imagination'   
Niagara-on-the-Lake, a popular cruising destination in Canada   
The crowd-pleasing comforts of catamaran cruising   
Death by Dinghy   
'Sailing Stones' of Death Valley seen in action for the first time   


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 NH
LocalAds   DE  ES  FR  IT