The increase in size and frequency of large hurricanes that make landfall from the Gulf of Mexico also is resulting in more tornadoes that form from the storms, according to a new report from researchers at the Georgia Institute of Technology.

“As the size of landfalling hurricanes from the Gulf of Mexico increases, we’re seeing more tornadoes than we did in the past that can occur up to two days and several hundred miles inland from the landfall location,” James Belanger, a doctoral student in the School of Earth and Atmospheric Sciences at Georgia Tech and lead author of the paper, said in a statement.

The findings, reported in Geophysical Research Letters’ Sept. 3, 2009, issue and online, are the first to quantify the risk of tornadoes from hurricanes. While it is well known that tornadoes may form in the area where hurricanes strike land, there hadn’t been detailed research because observations of tornadoes were too sporadic prior to the installation of the NEXRAD Doppler Radar Network in 1995.

Belanger and co-authors Judith Curry, professor and chair of the School of Earth and Atmospheric Sciences at Tech, and research scientist Carlos Hoyos wanted to create a model using the more reliable tornado record that’s existed since 1995. Their model for hurricane-induced tornadoes uses four factors that serve as good predictors of tornado activity: size, intensity, track direction and whether there’s a strong gradient of moisture at midlevels in the storm’s environment.

The team looked at 127 tropical cyclones from 1948 up to the 2008 hurricane season and went further back to 1920, modifying their model to account for the type of data collected at that time. They found that since 1995 there has been a 35 percent percent increase in the size of tropical cyclones from the Gulf compared to the previous active period of storms from 1948-1964, which has lead to a doubling in the number of tornadoes produced per storm. The number of hurricane-induced tornadoes during the 2004 and 2005 hurricane seasons is unprecedented in the historical record since 1920, according to the model.

“The beauty of the model is that not only can we use it to reconstruct the observational record, but we can also use it as a forecasting tool,” Belanger said.

To test how well it predicted the number of tornadoes associated with a given hurricane, they input the intensity of the storm at landfall, it’s size, track and moisture at mid-levels, and were able to generate a forecast of how many tornadoes formed from the hurricane. They found that for Hurricane Ike in 2008, their model predicted exactly the number of tornadoes that occurred, 33. For Hurricane Katrina in 2005, the model predicted 56 tornadoes, and 58 were observed.

The team’s next steps are to take a look to see how hurricane size, not just intensity (as indicated by the Safir-Simpson scale), affects the damage experienced by residents.

“Storm surge, rain and flooding are all connected to the size of the storm,” said Curry. “Yet, size is an under-appreciated factor associated with damage from hurricanes. So it’s important to develop a better understanding of what controls hurricane size and how size influences hurricane damage. The great damage in Galveston from Hurricane Ike in 2008 was inconsistent with Category 2 wind speeds at landfall, but it was the large size that caused the big storm surge that did most of the damage.”

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The dead zone in the Gulf of Mexico is expected to grow this year to between 7,400 and 8,400 square miles, a size roughly equivalent to the state of New Jersey, according to researchers at the University of Michigan.

That means the zone will be among the top three largest on record; the largest oxygen-starved zone reached 8,484 square miles in 2002.

The dead zones are inadvertently man made: In a sort of reverse circle of life, fertilizer and livestock waste runoff from farms and lawns across the United States overfeeds the Mississippi and other rivers with nitrogen, which prompts massive algae growth in the Gulf of Mexico. The algae sinks and is consumed by bacteria, a process that depletes oxygen supplies along the bottom and lower water levels, choking off aquatic plants and animals. Fish, shellfish and other plants die for lack of oxygen (hypoxia).

The phenomenon has been underway for decades, but has reached its largest proportions in recent years.
“The growth of these dead zones is an ecological time bomb,” said Donald Scavia, a professor at the U-M School of Natural Resources and Environment and director of the U-M Graham Environmental Sustainability Institute. “Without determined local, regional and national efforts to control them, we are putting major fisheries at risk.”

Scavia’s forecasts also include annual dead zone predictions for the Chesapeake Bay, which this year is expected to see a decrease in the size of the dead zone, though it is due to declining runoff resulting from less area precipitation and not pollution reduction.

The Gulf hypoxia research team is supported by the U.S. National Oceanic and Atmospheric Administration’s Center for Sponsored Coastal Ocean Research and includes scientists from Louisiana State University and the Louisiana Universities Marine Consortium.

See an animation of how dead zones are created at National Oceanic and Atmospheric Administration website.

Copyright © 2009 Green Right Now | Distributed by Noofangle Media

By Shermakaye Bass
Green Right Now

The world is not our oyster. At least, not according to The Nature Conservancy, which presented a pioneering survey on the state of global shellfish to the International Marine Conservation Congress in Washington, DC in late May that uncovered some startling statistics.

Conducted by Nature Conservancy scientists from five continents over a five-year period, the first-ever report states that 85 percent of the world’s oyster reefs have disappeared over the last 150-odd years, largely due to over-harvesting, poor water quality and degraded environments. The complex habitats, also called oyster beds by some, are vital to the world’s bays and estuaries. And as go the reefs, the report warns, so, potentially, go much larger, interlocking marine ecosystems.

“One third of the places that we looked at globally were functionally extinct,” lead author Mike Beck, senior scientist for the Conservancy’s Marine Initiative, told GreenRightNow. “That means they had less than 1 percent remaining of the former habitat, as best as we could tell. That occurs on every continent except Antarctica – where oysters don’t occur.”

He explained that European coasts once thrived with oyster reefs, and even the once legendary fisheries of America’s West Coast are in dire straits.

“Now, there’s virtually nothing left in all of Europe. We’ve also seen extraordinary declines in the Northwest and Chesapeake – and we’ve almost forgotten (laymen, not scientists) that there used to be a native Olympia Oyster out there, from British Columbia to Mexico. The San Francisco Bay used to be full of them,” Beck said, pointing out that one famous American writer made a few bucks off the Golden Gate’s oyster trade, in more ways than one.

Flooding along the Mississippi River and its tributaries is creating a secondary environmental problem that’s not so secondary. As record-breaking runoff carrying sewage and fertilizers heads to the Gulf of Mexico, researchers and federal officials fear it will cause the largest algal bloom ever in the coastal waters.

The “bloom” causes a dead zone each summer as the overgrowth of algae promoted by the phosphorus and nitrogen-rich run off depletes the off shore waters of oxygen, killing or reducing the populations of shrimp, oysters and other marine life.

“The Gulf’s world class recreational and commercial fishing is at stake,” explained Garret Graves, chairman of the Louisiana Coastal Protection and Restoration Authority and a member of a joint federal-state task force that met last week in New Orleans to address the problem.

“This industry is not only a major contributor to the region’s economy, but is a huge part of the heritage of the people of our state and region,’’ he said. “The culture of fishing has shaped South Louisiana and the rest of the Gulf and we must do all we can to preserve that culture.”

Not to mention the related food and jobs.

The task force is asking citizens upstream to try to reduce the “nutrient pollution” by reducing nitrogen and fertilizer dumping into the Mississippi and through better watershed and conservation practices.

The task force was formed in 1998. Its members include representatives from several federal agencies, including the EPA and the U.S. Department of Agriculture, and officials from Mississippi River states as well as Ohio, whose Ohio River contributes to the Mississippi.

For more information see the task force action plan.

Copyright © 2008 | Distributed by Noofangle Media