New system aims to predict dangers at sea

A mix of strong winds, rough seas and frigid surface air and sea temperatures created the dangerous icing conditions that sank the New Bedford fishing vessel Lady of Grace in Nantucket Sound on the night of Jan. 26, 2007. All four fishermen onboard the vessel died at sea.

Scientists at UMass Dartmouth's School for Marine Science and Technology and the Woods Hole Oceanographic Institution have developed a new technology they hope will prevent another tragedy caused by icing conditions, which can coat a vessel's deck and rigging with heavy ice that alters stability and increases the likelihood of capsizing.

The Northeast Coastal Ocean Forecast System, developed in part by SMAST scientists Changsheng Chen and Brian Rothschild and WHOI scientist Robert Beardsley, uses a mix of ocean and weather models to generate three-day forecasts for icing potential, water temperature, wind speed and other conditions in Northeast coastal areas.

What sets the system apart from other forecast models is its high resolution, which allows forecasters to make detailed predictions about weather and ocean conditions within specific bodies of water, such as Buzzards Bay or Georges Bank.

To test whether their system could accurately predict icing dangers, the scientists and their research team used it to reconstruct surface weather and ocean conditions in Nantucket Sound on the night of the Lady of Grace sinking.

Fishermen had speculated that icing was to blame for the tragedy.

A Coast Guard report, issued a year after the sinking, confirmed that ice buildup on the 75-foot dragger's rigging and superstructure had most likely caused the vessel to roll over and sink about 12 miles off Hyannis.

The researchers found that at 10 p.m. on Jan. 26, 2007, conditions in Nantucket Sound included northwesterly winds increasing to greater than 22 mph, air temperatures below -4 degrees Fahrenheit and surface water temperatures of about 36 to 37 degrees Fahrenheit.

They plugged those values into an existing formula to calculate the predicted icing rate for vessels traveling in different areas of Nantucket Sound. They concluded that the Lady of Grace was likely "steaming into waves in an area with mid-moderate up to heavy icing rates" at the time of its disappearance, according to a paper written by Dr. Chen and Dr. Beardsley.

The predicted conditions were consistent with the Coast Guard's conclusion that the Lady of Grace experienced rapid icing that caused it to capsize.

"We came up with something from the model, which seems quite plausible with what actually happened," Dr. Beardsley, a physical oceanographer for WHOI, said.

Dr. Chen, a coastal oceanographer who directs SMAST's Marine Ecosystem Dynamics Modeling Research Laboratory, showed a Standard-Times reporter a map of Nantucket Sound divided into areas with different icing rates predicted by the new forecast system. A star in the center of the map identified the spot where the sunken Lady of Grace was found two days after it disappeared. Most of the star was positioned in a red section of the map, which had the highest icing rate. The map showed lower icing rates in other parts of the sound.

Dr. Chen explained that if the captain of the Lady of Grace had access to the same map or to a detailed forecast of icing conditions in Nantucket Sound, he would have been able to chart a different course that avoided areas with high icing potential.

Dr. Beardsley agreed.

"If the vessel was much closer to shore (the sinking) wouldn't have happened or if it had huddled behind the south side of Nantucket and stopped, it would not have had a problem; but it was steaming into it, almost directly into the wind and waves," he said.

The scientists are working with NOAA's National Weather Service in Taunton to see if their icing forecasts could be incorporated into the agency's marine forecasts to make them more specific.

Joseph DelliCarpini, science and operations officer at the weather service in Taunton, said the agency plans to evaluate their system this winter as it monitors icing conditions.

The weather service sometimes includes warnings for heavy freezing spray in its coastal waters forecasts for mariners, but Mr. DelliCarpini admitted that the agency's meteorologists "don't have a good prediction system" for icing.

The problem with current NWS icing forecasts, Dr. Beardsley said, is that they cover a broad area, even though icing may only be a problem in certain locations.

The new forecast system could help with that, he said.

Mr. DelliCarpini shares his optimism. Over time, predictions made by the system could help identify specific areas within Nantucket Sound and other bodies of water that are prone to icing, he said.

In addition to icing, the weather service is monitoring the system to see if it can enhance flood predictions, he added.

"We think it is pretty good," he said. "Coastal flooding on the South Coast has always been a problem and it's something that has not been modeled that well."

The Northeast Coastal Ocean Forecast System has other practical applications such as aiding in Coast Guard search and rescue missions. Dr. Chen has been corresponding with Arthur A. Allen, an oceanographer who works for the U.S. Coast Guard's Office of Search and Rescue.

Mr. Allen said the Coast Guard is considering incorporating the system into the agency's search planning tool, which uses ocean circulation models from NOAA and the U.S. Navy to predict the location of people, life boats, vessels and other "search objects" that are moved by the wind and ocean currents.

The system would allow the Coast Guard to make search predictions for inshore areas "where we certainly have lots of cases," Mr. Allen said. The agency's current models make predictions for offshore areas but do not provide a high level of detail for inshore areas, he said.

Dr. Rothschild, a fisheries biologist who chairs the New Bedford Oceans and Fisheries Council, spoke enthusiastically about the system's potential as a research tool for fisheries management, coastal pollution and climate change.

He explained that the system's high degree of resolution provides data on small-scale currents, water temperature, salinity and other factors that affect fish recruitment, or the amount of young fish that grow big enough to be caught by fishermen.

Another benefit of the system is that it can be adapted to any shoreline in the world.

For the Beijing 2008 Olympic Games in China, Dr. Chen used the system to forecast wind and currents along the coast of Qingdao City. The forecasts were made available to sailing teams from all countries so that nobody had a competitive advantage when racing in the area, which is known for having complex currents.

The door to Dr. Chen's office at SMAST features a colored photograph of two Canadian sailors racing in their boat. Scrawled across the picture is a message for his lab team: "Thank you for your help during the Olympics."

The forecast system has been operational since the spring and is available to the public through the SMAST Web. The system was funded through grants from the National Oceanic and Atmospheric Administration, National Science Foundation, Massachusetts Marine Fisheries Institute and MIT Sea Grant College Program.