Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New tools to forecast hurricane rainfall inland

20.06.2007
All eyes are on where hurricanes make landfall, but the massive storms actually cause the most deaths inland, where severe flooding often surprises residents.

Now, researchers are learning how to predict where tropical storms and hurricanes will dump the most rain — even days after — and hundreds of miles away from — landfall.

In a paper in the current issue of the journal Professional Geographer, Corene Matyas, an assistant professor of geography at the University of Florida, outlines new tools to predict how the storm’s intensity, distance it has moved inland and landscape topography alters its “rain shields” — the bands of heavy rain so visible in Doppler radar images. Among other things, her tools proved adept at modeling observations that when hurricanes or tropical storms encounter the Texas hill country or the Appalachian Mountains, their rain shields tend to line up in the same direction and with the same orientation as the underlying topography.

“There are a lot of different things that can affect where the rainfall can occur in the storm and how heavy that rainfall will be,” Matyas said. “Our goal is to work toward predicting how those factors will determine the rainfall pattern.”

Historically, hurricanes have proven most fatal at landfall, with coastal residents overcome by storm surge and high winds. But over the past four decades, forecasters have become more skilled at predicting hurricanes’ tracks over open water, enabling most coastal residents to flee or prepare for the storms well in advance.

As a result, the highest proportion of hurricane and tropical fatalities has shifted inland. One study cited in the Matyas paper found 59 percent of deaths from tropical storms or hurricanes between 1970 and 1999 occurred because of heavy rainfall rather than wind or storm surge. As storms track inland, they inevitably ensnare more cities and towns. In 1998, Tropical Depression Charley left 20 people dead near Del Rio, Texas, more than 200 miles from where the storm made landfall, Matyas notes.

Researchers are developing some models for forecasting inland rain patterns, but they have difficulty accounting for the lopsided or elongated shape the pattern often takes, with most if not all rain falling on one side of the storm. A common assumption is that rainfall will decrease as the hurricane moves away from the ocean, which is generally true but may be obviated by other weather systems and local landscape.

Matyas’ goal was to find new tools to improve the models.

She studied radar data from 13 U.S. storms that made landfall between 1997 and 2003, then used a common tool in geography — geographical information systems, or GIS — to measure how rainfall patterns changed. GIS is a computer system that makes it possible to analyze spatial patterns of data. It is often used to track things such as voting patterns, but using GIS in meteorology — where spatial patterns change — is relatively new, Matyas said.

Matyas outlined the edge of the rain shields using radar data, then measured their shapes by calculating characteristics such as the position of their center of mass. She repeated the analysis for each hour that the storms were over land. She then used a statistical technique, discriminant analysis, to determine which shape and size best place the storms into groups based on their intensity, how far they travel inland and the topography they encounter. The success of the discriminant analyses indicates that these shape measures could serve as predictive tools for future rainfall models.

In a demonstration of the potential, the shape measures helped to confirm that that the orientation of storms’ rain shields corresponds closely to the orientation of the land topography.

With hurricanes crossing Texas hill country, the rain shields tend to line up parallel to the main axis of the hills, running west to east. Storms near the Appalachians also line up parallel to the mountains, whose axis runs southwest to northeast, with the heaviest rain consistently occurring to the west of the track. This is due to a combination of the mountains and a wedge of cold and dry continental air forcing the moist air upward, causing the water vapor to condense and fall to the ground as rain. This phenomenon does not happen with the Texas storms, as the dry continental air masses over Texas are similar in temperature to tropical moist air masses that accompany hurricanes.

Frank Marks, a research meteorologist and director of the National Oceanic and Atmospheric Administration’s Hurricane Research Division, said Matyas’ conclusions “have a lot of merit in terms of understanding the structure, size and shape of the rain shield.”

He said the next step is to add rainfall amount to the variables. The end goal: a model that will provide inland residents with the same targeted advance warnings and watches that coastal residents get today — but for heavy rainfall rather than wind or storm surge.

Corene Matyas | EurekAlert!
Further information:
http://www.ufl.edu

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>