On Feb. 8, 2005, when British sailor Ellen MacArthur and her 25-meter trimaran crossed an imaginary finish line off the south coast of England, she completed the fastest single-handed nautical voyage around the world. After beginning her quest on Nov. 27, 2004, she sailed 27,000 miles without stopping in just 71 days, 14 hours, 18 minutes and 33 seconds.

To subject oneself to cramped living quarters, freeze-dried meals, desalinated sea water to drink and constant sleep deprivation—on average she slept just 30 minutes at a time—is arduous enough. To do it alone through some of the most inhospitable waters on the planet—particularly the Southern Ocean— takes an impressive level of courage and stamina.

The Southern Ocean is often where the “real” sailing begins. It’s the playground for icebergs and their more dangerous dandruff—the small- to medium-sized ice pieces called “growlers” and “bergy bits” that can hole a boat if hit. When MacArthur reached this leg of her journey on New Year’s Day she was on permanent iceberg alert for three days.

Although MacArthur didn’t see any other boats during her 15,000-mile stretch, she wasn’t actually alone. Another flotilla of sailors competing in the single-handed, around-the-world Vendée Globe race had entered the iceberg sandbox just before Christmas. However, these competitors had a leg up on MacArthur. To complement their on-board radar, they were provided with radar satellite-based text information pinpointing the size and position of detected targets and the probability of those targets being icebergs.

In an attempt to help racers plot the fastest, safest route through the iceberg minefield, race organizers commissioned Richmond, British Columbia-based RADARSAT International (RSI) to acquire several RADARSAT-1 scenes and analyze them for the presence of icebergs. The Canadian satellite company sent text bulletins reporting detected icebergs and their positions to race organizers, who then passed them on to the sailors. Organizers reported that the sailors welcomed this first-ever trial of radar satellite-based iceberg information.  “It was very helpful to have at least some information on the presence of icebergs,” relates Bruce Schwab, skipper of the  monohull Ocean Planet.

Derived from RADARSAT-1’s Synthetic Aperture Radar (SAR) sensor, iceberg information also was welcomed by four catamaran crews racing between 50 and 62 degrees south during their bid to win the inaugural Oryx Quest 2005 nonstop, around-the-world race that began Feb. 5. Acquired and processed in near real-time by RSI, 15 scenes were sent to iceberg-detection experts at C-CORE, a remote sensing company based in St. John’s, Newfoundland, Canada, who then produced text bulletins of iceberg positions.

Unlike these racers who contend with treacherous ice for a few days purely for the love of sport, commercial mariners
battle the frozen rock everyday for a living. And unlike in the boat-racing world, where having SAR-based ice information is a recent bonus, ice charts for marine navigation are essential. Although the savage elements of the Southern Ocean deserve respect, its northern parallel counterpart encompassing the North Atlantic and Labrador and Baltic Seas features sea ice and icebergs as regular as the sunrise.

Fortunately for ship captains, the operational use of SAR satellite imagery for sea ice and iceberg monitoring is well solidified. Indeed, for nearly a decade RADARSAT-1 imagery has been the backbone for ice-charting services provided by the Danish Meteorological Institute (DMI), Finnish Ice Service (FIS) and the Canadian Ice Service (CIS).

Simply put, says DMI’s chief of ice and remote sensing division Henrik Steen Andersen, “No RADARSAT-1, no ice service.”


It’s All in the Details
Charged with monitoring and charting a 1 million-square-kilometer area around Greenland, home to the infamous icy Cape Farewell, DMI personnel receive daily RADARSAT-1 ScanSAR Wide imagery (500- x 500-kilometer swaths at 100 meters resolution). Combining the RSI imagery with National Oceanic and Atmospheric Administration (NOAA) AVHRR data and weather information, DMI analyzes the imagery, charts the presence of ice—type of ice, concentration of ice, ice-edge boundary and icebergs—and sends the information to ships navigating through ice-infested waters. DMI occasionally complements its RADARSAT-1 data with ASAR imagery from the European Space Agency’s Envisat satellite. According to Andersen, satellite coverage has enabled DMI to reduce its aircraft fleet to one helicopter dedicated solely to reconnoiter in-shore shipping routes.

“With the satellite imagery we can provide a more detailed and more accurate chart than with airborne-derived charts,” he says. “Our customers are much happier with our service now.”

Based on the accuracy and rapid delivery of DMI’s ice information, a new customer, AgipKCO, came into the fold in February 2005 to test DMI’s service in a new geographic area, the Caspian Sea. Requiring ice-monitoring services to support its oil exploration and logistic operations, AgipKCO received ice charts sourced from data provided by RADARSAT-1 and NASA’s MODIS sensor aboard the agency’s Terra and Aqua satellites to help staff plot safe navigation routes for its tankers, oil rigs and icebreakers. The company also used the RADARSAT-1 imagery as a backdrop to its vessel-monitoring system.
 

Charting the Baltic
According to Ari Seina, head of FIS, at least 2,000 large vessels sail the Baltic Sea at any given time. Annually, about 700 million tons of goods are transported across the Baltic. Finland alone annually transports about 100 million tons of goods, 40 percent during the winter. With an overall ice season that can last six months (the longest stretch being in the North), an ice service to guide ships to safe harbor is essential.

As part of the Finnish Institute of Marine Research, FIS has integrated satellite imagery into its ice-charting service since 1968. The first SAR imagery was acquired in 1993 with the launch of the European Space Agency’s ERS-1 satellite. In 1998, FIS expanded its radar repertoire to include RADARSAT-1 and now also uses Envisat imagery. This imagery, coupled with other data sources, is used to provide mariners with daily ice charts detailing the ice conditions from the ice edge to harbors.

“We estimated that 60 percent of the visual-infrared imagery we use is useless because of cloud cover,” says Seina. “And when there are clouds there is typically a lot of ice movement and change. The ability of RADARSAT-1 to see through the clouds to monitor all those changes, along with its 500-kilometer-wide coverage, has offered an evolution in ice monitoring.”

FIS also uses RADARSAT data to provide an operational ice-charting service to Finnish and Swedish icebreakers, which use the data for real-time ice navigation. According to Seina, this has made traffic movements smoother and reduced ships’ sailing times in ice. Since the introduction of radar imagery into its service, FIS has been able to steadily decrease its aircraft fleet and number of flight hours. Today, the service no longer uses any airborne data for ice charting.

Going with the Floe
The reliance on radar satellite imagery has enabled CIS to significantly reduce its aircraft flight hours as well.

“Before RADARSAT-1, we were flying about 2,200 hours a year with two aircraft,” recalls Dean Flett, remote sensing manager with CIS in Ottawa. “Those costs peaked at about $15 million a year. Last year, our lone SLAR-equipped aircraft flew only 700 hours at a cost of $2 million.”

A veteran user of RADARSAT-1 imagery, CIS now provides 15 times the data coverage of its previous airborne solution and saves more than $6 million (CDN) in expenditures annually, according to Flett.

The CIS mandate is to promote safe and efficient maritime operations in hazardous ice conditions in Canada’s eastern territorial waters—an icy web about 5 million square kilometers in size—particularly the area around the Gulf of St. Lawrence and St. Lawrence River, which supports the largest volume of marine traffic. CIS personnel are most concerned with charting ice positions and ice types in an often dynamic environment—open water can become pack ice in a few hours—as well as identifying the roughly 40,000 icebergs that migrate through every year.

As the core dataset for its daily ice analysis charts, CIS receives 10-15 RADARSAT-1 ScanSAR scenes a day. Combining them with other data sources, ice forecasters map the presence of ice floes and icebergs and provide the maps to its predominant client, the Canadian Coast Guard, as well as commercial shipping companies. Envisat ASAR data also are used as a complementary dataset for the charts.

Radar’s Future Looks Bright
Because radar imagery is such a vital component of CIS’ ice services, the agency has staunchly supported a wealth of research into the operational use of RADARSAT-2 for continued sea ice and iceberg monitoring applications. In particular, CIS, as well as other ice-service organizations such as FIS and DMI, are interested in RADARSAT-2’s polarimetric capabilities and the suggested improvements they will offer for ice applications.

Scheduled to launch in early 2006, RADARSAT-2 will provide SAR imagery at horizontal, vertical and cross polarization across a range of resolutions from three to 100 meters, with swath widths ranging from 20-500 kilometers. In addition to delivering all RADARSAT-1 image modes, RADARSAT-2 will offer improved revisit times by providing the imaging modes to both the right and left side of the satellite track.

In addition, RADARSAT-2’s multipolarization feature is a capability that enables the SAR sensor to send and receive different combinations of polarized waves simultaneously, enabling users to identify a greater variety of surface features and targets. The satellite will be able to record in HH, VV, HV and VH polarizations simultaneously. With such flexibility, users can tailor acquisitions to more specifically suit the problem they’re trying to solve, whether determining ice from open water, classifying ice types such as first-year ice or multiyear ice, or distinguishing icebergs from ships.

 
Extensive research conducted during the last two years, as well as early results from ongoing projects and operational trials, indicate that RADARSAT-2’s polarization modes—particularly dual polarization—will significantly improve the ability to determine ice-edge location, ice concentration, ice type, ice classification and the presence of icebergs and discrimination of icebergs from ships.

Notes Flett, “We’re very hopeful that the promising results found to date using airborne data—and, more recently, Envisat imagery—will in fact be realized with RADARSAT-2’s data, particularly with dual-polarization data.”

Andersen and Seina also are hopeful that the research results become reality, as they already have plans to integrate the new dataset once it’s available.
 

Research Gains Momentum
Much of these positive iceberg-related results have come from research conducted by C-CORE. With a heavy emphasis on providing remote sensing and ice engineering services to offshore oil and gas clients operating in the Grand Banks off the east coast of Newfoundland, C-CORE has a vested interest in the ability to use SAR imagery for iceberg detection. An avid user of RADARSAT-1 imagery since 1996, C-CORE engineers began studying the feasibility of applying RADARSAT-2 data to operational ice monitoring services in 2003. In particular, they have focused on the satellite’s potential to distinguish icebergs from ships and ice floes—a problematic area for RADARSAT-1.

Using Envisat ASAR multipolarization data, engineers are able to demonstrate a nearly 90 percent classification rate with dual polarization and close to 100 percent classification with quadrature polarization (quad pol) data, according to Desmond Power, C-CORE’s director of remote sensing.

“The potential for RADARSAT-2 for ship and iceberg discrimination is quite good,” he relates.

However, the quad pol data are likely to be used operationally in special circumstances only, because its swath will be too narrow.

Adds Power, “Operationally, the dual pol really shines, because with ScanSAR we’ll have a range from 150 kilometers to 300 kilometers. And we’ll have that wide mode data in dual polarization, which for iceberg detection will be quite useful.”
Detecting icebergs and discerning them from ships is crucial for safe, consistent offshore petrochemical operations.

 Although companies operating offshore platforms have elaborate measures in place to protect their structures, they’re still vulnerable to iceberg movements, and any undetected iceberg—no matter how small—is considered a risk to continuous operations. Terra Nova produces about 150,000 barrels of oil a day, and shutting down production to physically move the platform to avoid a collision with an iceberg could cost millions. Not surprisingly, these companies need to know if a detected target is a ship or an iceberg.

“The oil industry does not tolerate false alerts because shutting down is such an expensive decision,” says Power. “That is why tools such as SAR imagery can figure very prominently into offshore oil operations.”

With exploration moving into deeper waters, structures become even more vulnerable to icebergs because there is no shallow bathymetry to limit the size and speed of icebergs adrift.

“As you’re further away from the coastline, it becomes a challenge to do aerial surveillance,” explains Power. “That’s why the offshore industry continues to be very interested in Earth observation. It’s a more useful tool in deeper waters.”

Interested indeed. The oil and gas industry, along with the Canadian Space Agency, recently commissioned C-CORE and RSI to provide full-scale pilot studies using RADARSAT-1 and simulated RADARSAT-2 data for iceberg detection. Trials started in April 2005 and run until 2007.

That strong sense of protection pushing companies to continually hunt for tools to help mitigate the risk to offshore structures is the same feeling of protection displayed by boat-race organizers toward their racers. It was what steered Vendée Globe and Oryx Quest organizers toward radar imagery, and it will likely drive others to the sky when the next group of sailors pushes south.