Cape May-Lewes ferry a source of science data
It’s one of those stinking hot days at the beach.
And then you feel it.
The wind changes direction. It blows a little stronger and the air temperature drops almost instantly.
It’s the sea breeze and it’s often what makes the coast of Delaware just a little milder on those hot summer days, when the sand is blistering but the air is mercifully cooler thanks to an on-shore breeze. Farther inland, it’s so steamy the chickens are laying hard-boiled eggs, as the expression goes.
Scientists understand how a sea breeze forms, but less well-studied is how it can influence weather and the potential for wind power.
Dana Veron, associate professor of geography in the University of Delaware College of Earth, Ocean and Environment, is looking at the factors that influence Delaware’s sea breeze.
“Ultimately, the ability to predict sea breeze presence could help us forecast how and when wind turbines, clean sources of renewable energy will produce the most and the least energy,” Veron said.
Veron has a sea-going partner in her research. Special sensors and monitors in the bow-thruster compartment of the Cape May Lewes Ferry MV New Jersey take measurements of water temperature, salinity, dissolved oxygen and chlorophyll continuously as the ferry crosses Delaware Bay. The sensors measure barometric pressure, air temperature, humidity, wind speed and direction, water carbon dioxide and pH.
“It’s called a ‘ship of opportunity,’” Veron said. “It’s a vessel that can record data in areas and at times that traditional research vessels might not take regular measurements.”
Typically, research fleets maintained by university’s and college take samples only when they are on specific cruises. But the ferry follows the same path multiple times day after day, month after month and year after year. Adding the sampling devices — which presently upload data to a university server every time the ship is at port — allows collection of a steady stream of data.
The college partners with the Delaware River and Bay Authority, which runs ferries between Lewes and Cape May, New Jersey. The ferry operates two other vessels, the M V Delaware and the M V Cape Henlopen. Since ferry operations started in 1964, they have transported 11 million vehicles and 34 million passengers one 17-mile, one-way passage at a time.
The sensing equipment is only installed in the M V New Jersey, christened in 1974. The vessel is 320 feet long and can carry 800 passengers and 100 vehicles.
In 2011, Jonathan Sharp, now a professor emeritus, collaborated with the authority on a project to install the sensing equipment in one of the ferry boats. Sharp, who researched changes in water chemistry in the Delaware River for decades, extended his work to look at more subtle changes in the Delaware Bay.
The ferry typically takes a path where the ocean and bay intersect. When the boat crosses, water is pumped into the sensing system in the bow of the vessel. The monitoring equipment takes continuous measurements of environmental conditions such as water temperature and salt content.
Delaware is cooler than New Jersey
The readings give researchers a way to track water exchange between the ocean and Delaware Bay. In 2011, for instance, the system helped Sharp track dips in salinity after heavy rainfall from Hurricane Irene and Tropical Storm Lee a few days later. There was no such dip during Hurricane Sandy because there was less rain fall in the upper Delaware River.
The data provides the scientists with an on-going picture of what is happening in the Delaware Bay.
“The conditions monitored by the ferry affect the ecology of the entire Delaware Bay,” Sharp said. “This means that anyone who sails, swims, fishes or otherwise interacts with the bay is affected by its health.”
Earlier this year, Sharp turned the project over to Veron and Wei-Jun Cai, a university professor of oceanography. Cai studies both esturine pH — used to look at ocean acidification that can impact fish and shellfish populations — and carbon dioxide, a key indicator of climate change.
Veron is using the data collection system to take a closer look at the Delaware coastal sea breeze. As the ferry is going back and forth, “you can really see how temperature is different,” she said. It’s typically a little cooler on the Delaware side of Delaware Bay than on the New Jersey side, she said.
Veron graduate student Christopher Hughes started looking at Delaware’s sea breeze patterns by searching dates from eight meteorological stations in the university’s Delaware Environmental Observing System. They also looked at the National Data Buoy Center to find wind patterns at near shore and off shore stations. Their initial data search was from 2005 to 2012.
They concluded that winds across the Delmarva Peninsula move pollution, alter the temperature and play a key role both for farmers and for vacationers and the businesses that depend on them.
During the winter, the wind typically blows from the northwest. But during the summer, there is more variability in the prevailing southwest and southeast breezes.
The wind field on the Delmarva Peninsula is influenced by the Chesapeake Bay, the Delaware Bay and the Atlantic Ocean.
“We see crazy, strong sea breezes in the spring,” Veron said.
In summer, the breezes are most frequent on clear, sunny days when the land heats up quickly, she said. That creates a difference in temperature between the water and the land. The land is hot. The ocean is cooler and that cool air is pulled in toward the land. Besides that cool air, the sea breeze also can make it more humid and increase the chances of a late afternoon thunderstorm.
Data may determine wind turbine locations
For W. David Racine, of Rehoboth Beach, a longtime sailboat racer on Rehoboth Bay, understanding the sea breeze can mean the difference between winning a race and finishing near the back of the fleet. If he doesn’t anticipate a sea breeze he can end up on the wrong side of the race course once the wind starts to fill in from the ocean.
“That’s the great thing about here,” Racine said. “We do get that sea breeze.”
He’s seen fewer sea breezes this summer because ocean water temperatures just to the east of Rehoboth Bay are so warm, he said.
“We don’t get that temperature difference between the land and the water,” he said. “We’ve had a lot of north wind and that makes it a little hard to predict the sea breeze, he said.
The value in understanding this unique coastal wind pattern is that researchers and business people can use it to determine the potential for wind power, Veron said.
As the sea breeze is pushing inland, it can also be having at effect out at sea, she said. Knowing more about it, may ultimately help determine the best locations for wind turbines, she said.
Wind power was a hot topic in Delaware in 2007 and 2008, when Bluewater Wind proposed a wind park of 150 turbines in the ocean about 13 miles east of Rehoboth Beach. The project never got off the ground. Later, the University of Delaware built a land-based turbine at its Lewes Campus, which supplies much of the power needed on the site.
The project has drawn complaints from some nearby residents who say the turbine is noisy when the wind is out of some directions. Meanwhile, the university tried, unsuccessfully, to get a federal grant to build a near-shore turbine research park where companies and scientists could trial new and innovative technologies.
Veron has been studying sea breeze impacts since 2006 but now the ferry sensors have become a critical part of their data collection network.
Hughes continues to work on the science of predicting the sea breeze, she said.
Veron as working at the university’s Center for Carbon-free Power and discovered there was a lot of information available on overall wind but not much research on the variability in wind patterns — such as the sea breeze.
“The whole Mid-Atlantic Coast is really interesting,” she said. “There is more variability in the sea breeze than you might think.”
Reach Molly Murray at (302) 463-3334 or mmurray@delawareonline.com. Follow her on Twitter @MollyMurraytnj.