Navigation Links
2007 hurricane forecasts took blow from winds and Saharan dry, dusty air
Date:8/18/2008

A new analysis of environmental conditions over the Atlantic Ocean shows that hot, dry air associated with dust outbreaks from the Sahara desert was a likely contributor to the quieter-than-expected 2007 hurricane season.

Factors known to influence the number and intensity of hurricanes in a season, including El Nio, sea surface temperatures, wind, and sea level pressure, led to NOAA forecasts [identify what agency made these forecasts; otherwise it might be assumed they are from NASA] for an above-average 2007 hurricane season. However, the season, which runs from June through November, turned up six hurricanes a near normal number, but less than the 10 expected and far fewer than the record-breaking 15 hurricanes in 2005.

The difference between the 2007 and 2005 seasons could be due in part to the westward reach of Saharan dry air and dust over the North Atlantic, according to researchers, including Bill Lau of NASA's Goddard Spaceflight Center in Greenbelt, Md., and co-author of a study on this finding published Aug. 14 in the American Geophysical Union's Geophysical Research Letters. The study also confirms the possible role of Saharan dust in shattering predictions for the 2006 hurricane season, and has implications for more accurate predictions for future hurricane seasons.

Lau and colleagues previously reported that the presence of dust could have contributed to a weaker 2006 hurricane season than forecasters expected. Dust over the North Atlantic blocked some sunlight from reaching the ocean, accounting for 30 to 40 percent of the drop in sea surface temperatures measured between June 2005 and June 2006. The cooler sea surface increases atmospheric stability and also reduces the transfer of heat from ocean to atmosphere a major source of fuel that drives hurricanes.

Now, the team found that hurricane formation in 2007 was also hampered by Saharan dry air. They go further, however, to describe the extent to which the dry air and associated dust spread across the tropical North Atlantic, as seen by instruments aboard NASA satellites such as the Moderate Resolution Imaging Spectroradiometer. They created a "wind-stretch index," based on the east-west difference in wind speed over the tropical Atlantic. The index is connected to relative humidity over the tropical western Atlantic, and is a perfect measure of how far west dry air and dust from Africa extends over the North Atlantic.

The team found that instances of Saharan dry air and dust extending far west over the Caribbean were in sync with conditions that contributed to fewer hurricanes in both 2007 and 2006, including lower sea surface temperatures. They also found that the far-reaching western extent of dust in 2006 and 2007 was associated with less-than-normal humidity over the western North Atlantic.

"This index hasn't been looked at before," said Lau. "We introduce a way to relate wind stretch to dry air and dust, which correlate very well with humidity in the western tropical Atlantic."

The link between dust and humidity, the researchers say, could aid future forecasts. As dust outbreaks occur most often in early summer prior to peak hurricane season, researchers could use a measure of humidity in the western tropical Atlantic to gauge the extent of dust transport, possibly providing an additional parameter to estimate the following month's hurricane activity.

"The index we proposed may provide practical implications for the prediction of Atlantic hurricane activities," says Donglian Sun of George Mason University in Fairfax Va., and lead author of the study. "Further studies are needed to discern the general prediction capability of our results."

If the index is on target, the team believes it could also describe dust's role in past hurricane seasons. Records of historical wind data from ground stations could be applied to the index to infer the westward extent of dry air and dust long before satellites existed to "see" dust from above.


'/>"/>

Contact: Lynn Chandler
lynn.chandler-1@nasa.gov
301-286-2806
NASA/Goddard Space Flight Center
Source:Eurekalert

Related biology news :

1. Climates remote control on hurricanes
2. Soil, conservation experts to reflect on Hurricane Katrina disaster
3. Air quality forecasts for China
4. Air quality forecasts see future in space
5. Research forecasts increased chances for stormy weather
6. UGA researchers discover mechanism that explains how cancer enzyme winds up on ends of chromosomes
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/23/2017)... first robotic gym for the rehabilitation and functional motor sense evaluation of ... Italy . The first 30 robots will be available from June ... . The technology was developed and patented at the IIT laboratories and ... thanks to a 10 million euro investment from entrepreneur Sergio Dompè. ... ...
(Date:5/6/2017)... , May 5, 2017 RAM ... announced a new breakthrough in biometric authentication based ... quantum mechanical properties to perform biometric authentication. These new ... semiconductor material created by Ram Group and its ... entertainment, transportation, supply chains and security. Ram Group ...
(Date:4/18/2017)... 18, 2017  Socionext Inc., a global expert in SoC-based imaging ... server, the M820, which features the company,s hybrid codec technology. A ... Tera Probe, Inc., will be showcased during the upcoming Medtec Japan ... at the Las Vegas Convention Center April ... Click here for ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... October 12, 2017 , ... ... Market with the addition of its newest module, US Hemostats & Sealants. , ... thrombin hemostats, absorbable hemostats, fibrin sealants, synthetic sealants and biologic sealants used in ...
(Date:10/12/2017)... , ... October 12, 2017 ... ... has launched Rosalind™, the first-ever genomics analysis platform specifically designed for life ... Named in honor of pioneering researcher Rosalind Franklin, who made a major ...
(Date:10/11/2017)... ... October 11, 2017 , ... The CRISPR-Cas9 ... overexpression experiments and avoiding the use of exogenous expression plasmids. The simplicity of ... performing systematic gain-of-function studies. , This complement to loss-of-function studies, such as ...
(Date:10/11/2017)... ... 11, 2017 , ... ComplianceOnline’s Medical Device Summit is back for its 4th ... in San Francisco, CA. The Summit brings together current and former FDA office bearers, ... and government officials from around the world to address key issues in device compliance, ...
Breaking Biology Technology: