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 Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University

nachricht Climate change: Urban trees are growing faster worldwide
13.11.2017 | Technische Universität München

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: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>