Subscribe free to our newsletters via your
. Earth Science News .

NASA Study Could Improve Hurricane Strength Forecasts
by Staff Writers
Pasadena CA (JPL) Nov 29, 2012

Hurricane forecasters strive to predict where a storm is heading and how strong it will be. Since the early 1990s, they have significantly improved forecasts of hurricane paths in the Atlantic basin, by about two to four percent a year. But forecasts of hurricane intensity have improved much slower - less than one percent a year in the Atlantic basin since the mid-1980s.

Forecasters could soon be better able to predict how intense tropical cyclones like Hurricane Sandy will be by analyzing relative-humidity levels within their large-scale environments, finds a new NASA-led study.

Scientists from NASA's Jet Propulsion Laboratory, Pasadena, Calif., UCLA and the University of Hawaii at Manoa analyzed relative humidity data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft for nearly 200 North Atlantic hurricanes between 2002 and 2010.

The AIRS data were then compared with various types of post-storm data collected from all available sources by the National Oceanic and Atmospheric Administration's National Hurricane Center, including measured maximum sustained winds.

The researchers found the hurricanes that rapidly intensified tended to exist within a moister large-scale environment than weaker storms. The rapidly intensifying hurricanes had statistically significant higher relative-humidity levels in their environments than storms whose intensity was weakening or unchanged.

Lead author and former JPL postdoctoral scholar Longtao Wu, now an assistant researcher at the UCLA-JPL Joint Institute for Regional Earth System Science and Engineering, said the study could lead to improvements in hurricane intensity forecasts.

"Our results show relative humidity and its variations within a hurricane's large-scale environment may be useful predictors in improving intensity forecast models," Wu said. "This is the first satellite analysis to quantify this small but statistically significant correlation." Results of the study were published recently in the journal Geophysical Research Letters.

Hurricane forecasters strive to predict where a storm is heading and how strong it will be. Since the early 1990s, they have significantly improved forecasts of hurricane paths in the Atlantic basin, by about two to four percent a year. But forecasts of hurricane intensity have improved much slower - less than one percent a year in the Atlantic basin since the mid-1980s.

In other ocean basins, like the eastern and western North Pacific, improvements in tropical cyclone intensity forecasts are nearly 10 times smaller than those of track forecasts.

Changes in hurricane intensity are sensitive to numerous factors, both within the storms themselves and also in their surrounding environments. Environmental relative humidity is one factor, and it generally decreases the farther you get from a storm's center. Other factors include sea surface temperature, ocean heat content and vertical wind shear.

Wu and his colleagues sorted the AIRS relative humidity data by storm intensity and intensification rates, and classified them based on their distance from storm center and also by what quadrant of the storm they came from relative to the storm's direction of travel (front right, front left, rear right and rear left).

Generally, a hurricane's right side relative to its direction of travel is the most dangerous. This is because a hurricane's wind speed is amplified by the speed of its steering winds. Storm surge is also higher on a hurricane's right side.

The team found substantial differences in relative-humidity levels between storm quadrants. One factor may be the shape of the Atlantic basin. Hurricanes in the Atlantic usually travel to the west or northwest - regions that are drier, climatologically-speaking, than from where the storms originated. This causes the front two quadrants of Atlantic hurricanes to be drier than their rear two quadrants.

A unique result the team found is that in their front-right quadrants, rapidly intensifying hurricanes tended to have sharply higher amounts of upper tropospheric moisture near their centers than they did farther from their centers.

"We speculate that decreasing relative humidity levels farther from a storm's center may be an important factor in a cyclone's rapid intensification," said JPL co-author Hui Su.

"A drier environment farther from a storm's center limits the development of its outer rain bands and favors the growth of its inner core. Conversely, a wet environment farther from a storm's center can weaken a cyclone by making it easier for rain bands to form outside the storm's core, which compete with the inner core's growth."

"Most scientists have tended to view hurricane intensification as a process that takes place within a cyclone's inner core and depends more on smaller-scale processes than on a storm's large-scale environment," said JPL co-author Bjorn Lambrigtsen.

"This study shows a different path, and the usefulness of incorporating large-scale environmental data collected far away from a storm's center."

Su said NASA is exploring collaborations with NOAA forecasters to incorporate AIRS relative humidity data into NOAA's real-time hurricane prediction system.


Related Links
Atmospheric Infrared Sounder
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

USA's ancient hurricane belt and the US-Canada equator
Durham UK (SPX) Nov 22, 2012
The recent storms that have battered settlements on the east coast of America may have been much more frequent in the region 450 million years ago, according to scientists. New research pinpointing the positions of the Equator and the landmasses of the USA, Canada and Greenland, during the Ordovician Period 450 million years ago, indicates that the equator ran down the western side of North Amer ... read more

Fed official sees only slight GDP hit from Sandy

Haiti opts for ID security program

Chernobyl shelter construction reaches key landmark

CCNY Landscape Architect Offers Storm Surge Defense Alternatives

NASA Technologists Test 'Game-Changing' Data-Processing Technology

UTC Aerospace Systems Selects Headwall Hyperspectral Imaging Sensor For SYERS-2 Program

Samsung launches new Internet-connected camera

20 workers injured as tornado hits Italy steel plant

Seas rising 60 percent faster than UN forecast: study

World Bank to spend $6.4 mn on Gaza water project

Ocean acidification affecting live marine creatures in the Southern Ocean

Water Resources Management and Policy in a Changing World

Definitive study highlights polar ice melt

Canada, Denmark settle Arctic territorial dispute

Embracing data 'noise' brings Greenland's complex ice melt into focus

Beware of permafrost peril, climate talks told

Human transformation of land threatens future sustainability?

Bread wheat's large and complex genome is revealed

Sequencing the Wheat Genome in a Breakthrough for Global Food Security

Chinese industrialist buys top wine estate in landmark deal

Renewed flooding threatens Niger capital

NASA Study Could Improve Hurricane Strength Forecasts

How does a volcanic crater grow? Grab some TNT and find out

Woman dies as hundreds flee homes in flooded Welsh city

Ethiopia to stay in Somalia until AU takeover: PM

Algeria's ruling party eyes landslide in local elections

Madagascar to probe rights abuses by security forces

Trial of army mutineers begins in Burkina Faso

Long-held memory tenet challenged

A 3-D light switch for the brain

Scientists improve dating of early human settlement

Oldest home in Scotland unearthed

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement