September 6, 2007, 9:31 PM CT

Sensors Warn Of Emerging Hurricane's Strength

A new study supported by NASA and the U.S. Office of Naval Research takes forecasters one step further to improving their ability to predict just how powerful an oncoming storm may become by using highly-sensitive sensors located thousands of miles from the storm to detect lightning outbreaks within a hurricanes most dangerous area.

Scientists can now investigate with greater accuracy how the rate of lightning strikes produced within a hurricane's eyewall is tied to the changing strength of that hurricane. A hurricanes eyewall is the inner heat-driven region of the storm that surrounds the eye where the most intense rainfall and most powerful winds occur. By monitoring the intensity of lightning near a hurricanes eye, researchers will be able to improve their forecasts of when a storm will unleash its harshest conditions.

During the study, scientists used data from a growing network of new, long-range, ground-based lightning sensors, a NASA satellite and aircraft-based sensors. They explored the relationship between eyewall lightning outbreaks and the intensity of two of the most severe Atlantic storms on record before they made U.S. landfall: category five hurricanes Katrina and Rita. An article on this research, also supported by the U.S. Office of Naval Research, would be reported in the American Meteorological Society's Monthly Weather Review later this year......... Posted by: Tyler      Read more         Source

September 3, 2007, 11:47 AM CT

Secrets Of Red Tide

In work that could one day help prevent millions of dollars in economic losses for seaside communities, MIT chemists have demonstrated how tiny marine organisms likely produce the red tide toxin that periodically shuts down U.S. beaches and shellfish beds.

In the Aug. 31 cover story of Science, the MIT team describes an elegant method for synthesizing the lethal components of red tides. The scientists believe their method approximates the synthesis used by algae, a reaction that chemists have tried for decades to replicate, without success.

Understanding how and why red tides occur could help researchers figure out how to prevent the blooms, which cause significant ecological and economic damage. The New England shellfish industry, for example, lost tens of millions of dollars during a 2005 outbreak, and red tide killed 30 endangered manatees off the coast of Florida this spring.

The discovery by MIT Associate Professor Timothy Jamison and graduate student Ivan Vilotijevic not only could shed light on how algae known as dinoflagellates generate red tides, but could also help speed up efforts to develop cystic fibrosis drugs from a compound closely correlation to the toxin. Red tides, also known as algal blooms, strike unpredictably and poison shellfish, making them dangerous for humans to eat. It is unknown what causes dinoflagellates to produce the red tide toxins, but it may be a defense mechanism, possibly provoked by changes in the tides, temperature shifts or other environmental stresses......... Posted by: Tyler      Read more         Source

September 3, 2007, 11:43 AM CT

Looking For Life In And Under Antarctic Ice

Antarctica is home to the largest body of ice on Earth. Previous to approximately 10 years ago, no one thought that life could exist beneath the Antarctic ice sheets, which can be more than two miles thick in places, because conditions were thought to betoo extreme. However, Brent Christner, assistant professor of biological sciences at LSU, has spent a great deal of time in one of the world's most hostile environments conducting research that proves otherwise.

Christner's discoveries of viable microbes in ancient ice cores and subglacial environments coupled with the realization that large quantities of liquid water exist beneath the Antarctic ice sheet have changed the way biologists view life in Antarctica.

"More than 150 lakes have been discovered underneath nearly two-and-a-half miles of ice in Antactica," said Christner, "and most of these bodies of water have likely been covered by ice for at least 15 million years. The environmental conditions in the deep cold biosphere are unlike anything on the Earth's surface and this represents one of the most extreme habitats for life on the planet".

A time frame of up to one million years is mandatory for microbes in the atmosphere to be transported through the ice sheet and enter an Antarctic subglacial lake. Even though cells are preserved in the ice, the question of how the DNA of these organisms remains unscathed over such long periods of apparent metabolic inactivity still remains......... Posted by: Tyler      Read more         Source

August 31, 2007, 4:50 AM CT

Population movements, money and forest regrowth

A study of forest cover in El Salvador in the recent issue of BioScience presents novel findings on how economic globalization, land policy changes, and monies sent to family members by emigrants have transformed agriculture and stimulated forest regrowth. The study, by Susanna B. Hecht and Sassan S. Saatchi, employed socioeconomic data, land-use surveys, and satellite imagery to document substantial increases in the area of El Salvador covered by both light and heavy woodland since peace accords were signed in 1992.

Most analyses of forest cover in Central America have focused on loss of old-growth forests. In drawing attention to regrowth of woodland in a country that was extensively deforested during the 1970s, Hecht and Saatchi call for a renewed examination of social and economic influences on agricultural practices and their effects on forest extent. New growth forests, most often in a mosaic along with agriculture, can buffer declines in biological diversity and are extensively used by old growth species.

War drove a number of people to flee El Salvador during the 1980s and early part of 1990s, which led to a number of farms being abandoned. The country experienced a net increase in tree cover thereafter. Hecht and Saatchi found a 22 percent increase in the area with 30 percent tree cover, and a 6.5 percent increase in the area with more than 60 percent tree cover. Policies that encouraged sustainable agriculture contributed to the increase, the authors maintain......... Posted by: Tyler      Read more         Source

August 29, 2007, 9:47 PM CT

Greece Suffers More Fires In 2007

Greece has experienced more wildfire activity this August than other European countries have over the last decade, as per data from ESA satellites. The country is currently battling an outbreak of blazes, which began last Thursday, that have spread across the country killing more than 60 people.

ESA's ERS-2 and Envisat satellites continuously survey fires burning across the Earth's surface with onboard sensors - the Along Track Scanning Radiometer (ATSR) and the Advanced Along Track Scanning Radiometer (AATSR) respectively, known as the ATSR Word Fire Atlas, which is available to users online in near-real time.

The ATSR World Fire Atlas is the longest worldwide fire atlas available. Even if the atlas is not supposed to pick up all fires due to satellite overpass constraints and cloud coverage, it is statistically representative from one month to the other and from one year to the other.

Working like thermometers in the sky, the sensors measure thermal infrared radiation to take the temperature of Earth's land surfaces. Temperatures exceeding 308ºK at night are classed as burning fires. Data gathered from July 1996 to 28 August 2007 was used to plot the number of fires occurring monthly and show Greece has had four times the number of fires this August in comparison to its July and August 1998 records......... Posted by: Tyler      Read more         Source

August 28, 2007, 9:40 PM CT

Greenhouse caused the US warmth in 2006

Greenhouse gases likely accounted for over half of the widespread warmth across the continental United States in 2006, according to a new study that will be published 5 September in Geophysical Research Letters, a publication of the American Geophysical Union. Last year's average temperature was the second highest since recordkeeping began in 1895. The team found that it was very unlikely that the 2006 El Nino played any role, though other natural factors likely contributed to the near-record warmth.

When average annual temperature in the United States broke records in 1998, a powerful El Nino was affecting climate around the globe. Scientists widely attributed the unusual warmth in the United States to the influence of the ongoing El Nino. El Nino is a warming of the surface of the east tropical Pacific Ocean.

The research team, led by Martin Hoerling at the National Oceanic And Atmospheric Administration (NOAA) Earth System Research Lab in Boulder, Colorado, also found that greenhouse gas increases in Earth's atmosphere enhanced the probability of U.S. temperatures breaking a record in 2006 by approximately 15-fold compared to pre-industrial times. The authors also estimate that there is a 16 percent chance that 2007 will bring record-breaking warmth.

"We wanted to find out whether it was pure coincidence that the two warmest years on record both coincided with El Nino events," Hoerling said. "We decided to quantify the impact of El Nino and compare it to the human influence on temperatures through greenhouse gases"......... Posted by: Tyler      Read more         Source

August 27, 2007, 9:17 PM CT

Hot Spots And Fires From Space

Hot spots across Southeastern Europe from 21 to 26 August have been detected with instruments aboard ESA satellites, which have been continuously surveying fires burning across the Earth's surface for a decade.

Working like thermometers in the sky, the Along Track Scanning Radiometer (ATSR) on ESA's ERS-2 satellite and the Advanced Along Track Scanning Radiometer (AATSR) on ESA's Envisat satellite measure thermal infrared radiation to take the temperature of Earth's land surfaces.

Temperatures exceeding 312ºK (38.85ºC) are classed as burning fires by AATSR, which is capable of detecting fires as small as gas flares from industrial sites because of their high temperature. Worldwide fire maps based on this data are available to users online in near-real time through ESA's ATSR World Fire Atlas (WFA).

Smoke from some of the fires included in the WFA fire map was detected during the same period by Envisat's Medium Resolution Imaging Spectrometer (MERIS) optical instrument. While working in Full Resolution mode to provide a spatial resolution of 300 metres, MERIS captured smoke plumes arising from fires raging across Greece's southern Peloponnese peninsula, where fires have claimed the lives of at least 60 people since they began four days ago.

These images are available on ESA's MIRAVI website, which gives access to Envisat's most recently acquired images. MIRAVI, short for MERIS Images RApid VIsualisation, tracks Envisat - the world's largest Earth Observation satellite - around the globe, generates images from the raw data collected by MERIS and provides them online within two hours. MIRAVI is free and requires no registration......... Posted by: Brooke      Read more         Source

August 27, 2007, 8:21 PM CT

Long-term increase in rainfall seen in tropics

NASA researchers have detected the first signs that tropical rainfall is on the rise with the longest and most complete data record available.

Using a 27-year-long global record of rainfall assembled by the international scientific community from satellite and ground-based instruments, the researchers observed that the rainiest years in the tropics between 1979 and 2005 were mainly since 2001. The rainiest year was 2005, followed by 2004, 1998, 2003 and 2002, respectively.

"When we look at the whole planet over almost three decades, the total amount of rain falling has changed very little. But in the tropics, where nearly two-thirds of all rain falls, there has been an increase of 5 percent," says lead author Guojun Gu, a research scientist at Goddard Space Flight Center in Greenbelt, Md. The rainfall increase was concentrated over tropical oceans, with a slight decline over land.

Climate researchers predict that a warming trend in Earth's atmosphere and surface temperatures would produce an accelerated recycling of water between land, sea and air. Warmer temperatures increase the evaporation of water from the ocean and land and allow air to hold more moisture. Eventually, clouds form that produce rain and snow.

"A warming climate is the most plausible cause of this observed trend in tropical rainfall," says co-author Robert F. Adler, senior scientist at Goddard's Laboratory for Atmospheres. Adler and Gu are now working on a detailed study of the relationship between surface temperatures and rainfall patterns to further investigate the possible link. The study appears in the Aug. 1, 2007, issue of the American Meteorological Society's Journal of Climate......... Posted by: Tyler      Read more         Source

August 21, 2007, 5:49 PM CT

Hurricane Dean tracked from space

ESA satellites are tracking the path of Hurricane Dean as it rips across the Caribbean Sea carrying winds as high as 260 km/h. The hurricane, which has already claimed eight lives, is forecast to slam into Mexico's Yucatan Peninsula on Tuesday morning.

Dean was upgraded early Tuesday to a Category 5 - the highest on the Saffir-Simpson scale - before pummelling the peninsula. Knowing the strength and path of hurricanes is critical for issuing timely warnings; satellites are the best means of providing data on the forces that power the storm, such as cloud structure, wind and wave fields, sea surface temperature and sea surface height.

Instruments aboard ESA's Envisat and ERS-2 satellites allow them to peer through hurricanes. Envisat carries both optical and radar instruments, enabling scientists to observe high-atmosphere cloud structure and pressure in the visible and infrared spectrum.

The Medium Resolution Imaging Spectrometer (MERIS) optical instrument shows the swirling cloud-tops of a hurricane, while radar instruments such as the Advanced Synthetic Aperture Radar (ASAR) pierce through the clouds to show how the wind fields shape the sea surface and estimate their likely destructive extent.

ERS-2 uses its radar scatterometer to observe the hurricane's underlying wind fields. The scatterometer instrument works by firing a trio of high-frequency radar beams down to the ocean, then analysing the pattern of backscatter reflected up again. Wind-driven ripples on the ocean surface modify the radar backscatter, and as the energy in these ripples increases with wind velocity, backscatter increases as well. Scatterometer results enable measurements not only of wind speed but also of direction across the water surface......... Posted by: Brooke      Read more         Source

August 21, 2007, 5:27 PM CT

Volcano Safety For Ecuadorians

A geologist at Washington University in St. Louis is doing his part to make sure that the small Latin American country of Ecuador follows the Boy Scout motto: Be prepared.

Robert Buchwaldt, Ph.D., Washington University lecturer in earth and planetary sciences in Arts & Sciences, is the only scientist from America who sits on an international committee that is seeking ways to address the volcanic threat in Ecuador, particularly in Quito, a city of five million nestled against a volcano, Guagua Pichincha, that erupted just two years ago.

Buchwaldt, a couple of German researchers and a mixture of Ecuadorian politicians and citizens comprise the committee, which is called the Ecuadorian Volcanic Hazard Assessment Group. Its task is to develop an emergency plan in case of an eruption, which could happen again soon because magma temperatures are rising, as per Buchwaldt.

"Dealing with the threat of a volcano is not an uncommon problem," Buchwaldt said. "In North America, we have Seattle, which is adjacent to Mount St. Helens and two other volcanoes. They have a plan. We're trying to implement one in Quito, but the Latin American culture is different."

Money and communications problems.

A key problem is wealth, or the lack thereof, in Ecuador......... Posted by: Tyler      Read more         Source