Scientists have ended a long debate by proving that Earth’s core rotates faster than its surface.

Their research measured differences in the time it took seismic waves generated by nearly identical earthquakes to travel through Earth’s inner core.

According to geologists Jian Zhang of the Lamont-Doherty Earth Observatory (LDEO), Xiaodong Song of the University of Illinois at Urbana-Champaign and other co-authors of a paper in the Aug. 26 issue of the journal Science, Earth’s iron core is rotating approximately 1 degree per year faster than the rest of the planet.

“Whether the Earth’s core spins faster than its surface has been a hotly debated topic,” says Robin Reichlin, program director in the National Science Foundation (NSF)’s Division of Earth Sciences, which funded the research. “These new observations provide compelling support that it does.”

The scientists studied waveform doublets–earthquakes that are detected at the same seismic recording station in two different places, at two different times. A Sept. 2003, earthquake in the Atlantic Ocean near the South Sandwich Islands that was also detected in Ala., provided a near-exact match with one that had occurred in Dec.1993.

The seismograms were almost identical for shocks that had traveled only in the mantle and outer core. But seismic waves that had traveled through the inner core looked slightly different: they had made the trip through the Earth faster in 2003 than in 1993.

“The similar seismic waves that passed through the inner core show changes in travel times,” says Song. “The only plausible explanation is the faster rotation of the inner core.”

In all, the geologists analyzed 18 “doublets” from the South Sandwich Islands that were detected at Ala. seismic stations between 1961 and 2004.

“For decades, people thought of the Earth’s interior as changing very slowly over millions of years,” said scientist Paul Richards of LDEO, a co-author of the paper. “These results show that we live on a remarkably dynamic planet. They also underscore the fact that we know more about the moon than we know about what’s beneath our feet. Now we need to understand what is driving this difference.”

In addition to Zhang, Song and Richards, co-authors of the paper are Illinois graduate students Yingchun Li and Xinlei Sun and research scientist Felix Waldhauser. The work was also funded by the Natural Science Foundation of China.

Original press release: Earth’s Core Rotates Faster Than Its Crust, Scientists Say (NSF)

ESA radar satellites are peering through rain clouds to monitor the fast-changing situation across central and southern Europe, where torrential rainfall this week has led to heavy flooding.

Hundreds of people were driven from their homes as Alpine valleys were inundated across Austria, Germany and Switzerland. Widespread flooding was also reported in Bulgaria and Romania.

Large amount of water from Alpine valley flooding subsequently surged along central Europe’s river valleys towards the coast on Wednesday. The Isar and Inn Rivers were among rivers reported to have seen heavy surges, along with the Danube River they flow into - where the flood threat remains serious.

A huge low pressure system above Europe caused the rains, and it is uncertain when they will end. Many areas have been badly hit, among them the state of Voralberg in Austria and Bavaria in Germany.

In Switzerland the canton of Lucern and capital Berne were among affected areas, and helicopters plucked stranded people from rooftops. Total damage is estimated to stretch into millions of Euros.

Flooding is estimated to be the world’s most costly kind of natural disaster. With inundated areas typically visible from orbit, Earth Observation is increasingly being employed for flood response and mitigation.

On 25 August the Swiss Federal Office for Civil Protection formally activated the International Charter on Space and Major Disasters, meaning that member space agencies will prioritise delivery of satellite images and maps to support disaster response within the country.

ESA is a founder member of the Charter, which represents a joint effort by global space agencies to put resources at the service of rescue authorities responding to major natural or man-made disasters. To date since 2000 the Charter has been activated more than 80 times.

Meanwhile the Centre for Satellite-Based Crisis Information (ZKI) of the German Aerospace Center (DLR) plans to make use of ESA satellite data to produce information products covering German territory.

Satellite imagery is routinely used as an input for regional German flood forecasting centres serving the Upper Rhine and Mosel River Basins. Munich-based reinsurer Swiss Re has also recently participated in an ESA Earth Observation Market Development (EOMD) project with Earth Observation specialists VISTA in Munich and SERTIT in Strasbourg to investigate how satellite imagery can better document past disasters and improve the accuracy of risk models used to set insurance rates.

Flood risk analysis is also among the services offered by the Risk-EOS initiative, which offers Earth Observation-based services for flood and also fire risk management.

Risk-EOS services include historical flood mapping from archive data, and potential damage assessment, initially for the Elbe River Basin in Germany and the River Basin in Sweden, with the aim of expanding its coverage cover time. A flash flood awareness service is also currently being pioneered in France’s Entente Region.

Risk-EOS is part of ESA’s initial Services Element of Global Monitoring for Environment and Security (GMES), a joint initiative between ESA and the European Commission to develop a global monitoring capability for Europe harnessing all available ground- and space-based data sources.

Original press release: Central European flood surges watched from orbit (ESA)

Scientists at the National Center for Atmospheric Research (NCAR) have created a computer simulation showing Earth’s climate in unprecedented detail at the time of the greatest mass extinction in the planet’s history. The work gives support to a theory that an abrupt and dramatic rise in atmospheric levels of carbon dioxide triggered the massive die-off 251 million years ago. The research appears in the September issue of Geology.

“The results demonstrate how rapidly rising temperatures in the atmosphere can affect ocean circulation, cutting off oxygen to lower depths and extinguishing most life,” says NCAR scientist Jeffrey Kiehl, the lead author.

Kiehl and coauthor Christine Shields focused on the dramatic events at the end of the Permian Era, when an estimated 90 to 95% of all marine species, as well as about 70% of all terrestrial species, became extinct. At the time of the event, higher-latitude temperatures were

18 to 54 degrees Fahrenheit (10 to 30 degrees Celsius) higher than today, and extensive volcanic activity had released large amounts of carbon dioxide and sulfur dioxide into the atmosphere over a 700,000-year period.

To solve the puzzle of how those conditions may have affected climate and life around the globe, the researchers turned to the Community Climate System Model (CCSM). One of the world’s premier climate research tools, the model can integrate changes in atmospheric temperatures with ocean temperatures and currents. Research teams had previously studied the Permian extinction with more limited computer models that focused on a single component of Earth’s climate system, such as the ocean.

The CCSM indicated that ocean waters warmed significantly at higher latitudes because of rising atmospheric levels of carbon dioxide (CO2), a greenhouse gas. The warming reached a depth of about 10,000 feet (4,000 meters), interfering with the normal circulation process in which colder surface water descends, taking oxygen and nutrients deep into the ocean.

As a result, ocean waters became stratified with little oxygen, a condition that proved deadly to marine life. This in turn accelerated the warming, since marine organisms were no longer removing carbon dioxide from the atmosphere.

“The implication of our study is that elevated CO2 is sufficient to lead to inhospitable conditions for marine life and excessively high temperatures over land would contribute to the demise of terrestrial life,” the authors concluded in the article.

The CCSM’s simulations showed that ocean circulation was even more stagnant than previously thought. In addition, the research demonstrated the extent to which computer models can successfully simulate past climate events. The CCSM appeared to correctly capture key details of the late Permian, including increased ocean salinity and sea surface temperatures in the high latitudes that paleontologists believe were 14 degrees Fahrenheit (8 degrees Celsius) higher than present.

The modeling presented unique challenges because of limited data and significant geographic differences between the Permian and present-day Earth. The researchers had to estimate such variables as the chemical composition of the atmosphere, the amount of sunlight reflected by Earth’s surface back into the atmosphere, and the movement of heat and salinity in the oceans at a time when all the continents were consolidated into the giant land mass known as Pangaea.

“These results demonstrate the importance of treating Earth’s climate as a system involving physical, chemical , and biological processes in the atmosphere, oceans, and land surface, all acting in an interactive manner,” says Jay Fein, director of NSF’s climate dynamics program, which funded the research. “Other studies have reached similar conclusions. What’s new here is the application of a detailed version of one of the world’s premier climate system models, the CCSM, to understand how rising levels of atmospheric carbon dioxide affected conditions in the world’s oceans and land surfaces enough to trigger a massive extinction hundreds of millions of years ago.”

Original press release: Climate Model Links Higher Temperatures to Prehistoric Extinction (NCAR)

Dust from asteroids entering the atmosphere may influence Earth’s weather more than previously believed, researchers have found.

In a study to be published this week in the journal Nature, scientists from the Australian Antarctic Division, the University of Western Ontario, the Aerospace Corporation, and Sandia and Los Alamos national laboratories found evidence that dust from an asteroid burning up as it descended through Earth’s atmosphere formed a cloud of micron-sized particles significant enough to influence local weather in Antarctica.

Micron-sized particles are big enough to reflect sunlight, cause local cooling, and play a major role in cloud formation, the Nature brief observes. Longer research papers being prepared from the same data for other journals are expected to discuss possible negative effects on the planet’s ozone layer.

“Our observations suggest that [meteors exploding] in Earth’s atmosphere could play a more important role in climate than previously recognized,” the researchers write.

Scientists had formerly paid little attention to asteroid dust, assuming that the burnt matter disintegrated into nanometer-sized particles that did not affect Earth’s environment. Some researchers (and science fiction writers) were more interested in the damage that could be caused by the intact portion of a large asteroid striking Earth.

But the size of an asteroid entering Earth’s atmosphere is significantly reduced by the fireball caused by the friction of its passage. The mass turned to dust may be as much as 90 to 99 percent of the original asteroid. Where does this dust go?

The uniquely well-observed descent of a particular asteroid and its resultant dust cloud gave an unexpected answer.

On Sept. 3, 2004, the space-based infrared sensors of the U.S. Department of Defense detected an asteroid a little less than 10 meters across, at an altitude of 75 kilometers, descending off the coast of Antarctica. U.S. Department of Energy visible-light sensors built by Sandia National Laboratories, a National Nuclear Security Administration lab, also detected the intruder when it became a fireball at approximately 56 kilometers above Earth. Five infrasound stations, built to detect nuclear explosions anywhere in the world, registered acoustic waves from the speeding asteroid that were analyzed by LANL researcher Doug ReVelle. NASA’s multispectral polar orbiting sensor then picked up the debris cloud formed by the disintegrating space rock.

Some 7.5 hours after the initial observation, a cloud of anomalous material was detected in the upper stratosphere over Davis Station in Antarctica by ground-based lidar.

“We noticed something unusual in the data,” says Andrew Klekociuk, a research scientist at the Australian Antarctic division. “We’d never seen anything like this before — [a cloud that] sits vertically and things blow through it. It had a wispy nature, with thin layers separated by a few kilometers. Clouds are more consistent and last longer. This one blew through in about an hour.”

The cloud was too high for ordinary water-bearing clouds (32 kilometers instead of 20 km) and too warm to consist of known manmade pollutants (55 degrees warmer than the highest expected frost point of human-released solid cloud constituents). It could have been dust from a solid rocket launch, but the asteroid’s descent and the progress of its resultant cloud had been too well observed and charted; the pedigree, so to speak, of the cloud was clear.

Computer simulations agreed with sensor data that the particles’ mass, shape, and behavior identified them as meteorite constituents roughly 10 to 20 microns in size.

Says Dee Pack of Aerospace Corporation, “This asteroid deposited 1,000 metric tons in the stratosphere in a few seconds, a sizable perturbation.” Every year, he says, 50 to 60 meter-sized asteroids hit Earth.

Peter Brown at the University of Western Ontario, who was initially contacted by Klekociuk, helped analyze data and did theoretical modeling. He points out that climate modelers might have to extrapolate from this one event to its larger implications. “[Asteroid dust could be modeled as] the equivalent of volcanic eruptions of dust, with atmospheric deposition from above rather than below.” The new information on micron-sized particles “have much greater implications for [extraterrestrial visitors] like Tunguska,” a reference to an asteroid or comet that exploded 8 km above the Stony Tunguska river in Siberia in 1908. About 2150 square kilometers were devastated, but little formal analysis was done on the atmospheric effect of the dust that must have been deposited in the atmosphere.

The Sandia sensors’ primary function is to observe nuclear explosions anywhere on Earth. Their evolution to include meteor fireball observations came when Sandia researcher Dick Spalding recognized that ground-based processing of data might be modified to record the relatively slower flashes due to asteroids and meteoroids. Sandia computer programmer Joe Chavez wrote the program that filtered out signal noise caused by variations in sunlight, satellite rotation, and changes in cloud cover to realize the additional capability. The Sandia data constituted a basis for the energy and mass estimate of the asteroid, says Spalding.

The capabilities of defense-related sensors to distinguish between the explosion of a nuclear bomb and the entry into the atmosphere of an asteroid that releases similar amounts of energy — in this case, about 13 kilotons — could provide an additional margin of world safety. Without that information, a country that experienced a high-energy asteroid burst that penetrated the atmosphere might provoke a military response by leaders who are under the false impression that a nuclear attack is underway, or lead other countries to assume a nuclear test has occurred.

More detailed papers are slated for the Journal of Geophysical Research and the Journal of Meteoritics and Planetary Science, Pack says.

Original press release: Nature Paper: Burning Asteroids May Play ‘More Important Climate Role Than Previously Recognized’ (Sandia National Labs)

NASA and the National Oceanic and Atmospheric Administration (NOAA) today outlined research that has helped to improve the accuracy of medium-range weather forecasts in the Northern Hemisphere.

NASA and NOAA scientists at the Joint Center for Satellite Data Assimilation (JCSDA) in Camp Springs, Md., came up with procedures to improve forecasting accuracy. The scientists worked with experimental data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite.

They found incorporating AIRS data into numerical weather prediction models improves the accuracy range of experimental six-day Northern Hemisphere weather forecasts by up to six hours, a four percent increase. AIRS is a high-spectral resolution infrared instrument that takes 3-D pictures of atmospheric temperatures, water vapor and trace gases.

The instrument data have officially been incorporated into NOAA’s National Weather Service’s operational weather forecasts.

“NASA is assisting the world’s weather prediction agencies by providing very detailed, accurate observations of key atmospheric variables that interact to shape our weather and climate,” said Dr. Mary Cleave, associate administrator for NASA’s Science Mission Directorate. “The forecast improvement accomplishment alone makes the AIRS project well worth the American taxpayers’ investment.”

“This AIRS instrument has provided the most significant increase in forecast improvement in this time range of any other single instrument,” said retired U.S. Navy Vice Adm. Conrad C. Lautenbacher, Jr., Ph.D., Undersecretary of Commerce for Oceans and Atmosphere and NOAA administrator.

“Climate and weather forecasts are dependent upon our understanding current global ocean and atmosphere conditions. If we want to be able to predict what the weather will be like in the future, we must adequately define the global conditions today. Satellite data, like AIRS provides, is a vital link for NOAA to continuously take the pulse of the planet.”

“A four percent increase in forecast accuracy at five or six days normally takes several years to achieve,” said JSCDA Director, Dr. John LeMarshall. “This is a major advancement, and it is only the start of what we may see as much more data from this instrument is incorporated into operational forecast models at NOAA’s Environmental Modeling Center.”

The European Center for Medium Range Weather Forecasts began incorporating data from AIRS into their operational forecasts in October 2003. The center reported an improvement in forecast accuracy of eight hours in Southern Hemisphere five-day forecasts.

AIRS is the result of more than 30 years of atmospheric research. It is led by Dr. Moustafa Chahine of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. AIRS is the first in a series of advanced infrared sounders that will provide accurate, detailed atmospheric temperature and moisture observations for weather and climate applications.

The JCSDA is operated by NOAA, NASA, the U.S. Air Force and Navy. The goals of the center are to accelerate the use of observations from Earth-orbiting satellites to improve weather and climate forecasts, and to increase the accuracy of climate data sets.

Original press release: NASA/NOAA Announce Major Weather Forecasting Advancement (NASA)

Plumes of smoke from serious wildfires across Portugal fan into the Atlantic in this Envisat satellite view acquired on 21 August.

Dozens of wildfires are reported throughout the country, which has suffered one of its worst droughts for decades. Fanned by high winds, the fires have destroyed more than 140 000 hectares of land and killed at least 15 people.

Stricken areas include the vicinity of the city of Coimbra, Portugal’s third largest city, around 200 km northeast of Lisbon. On the outskirts of the city firefighters are attempting to keep the blazes at bay.

Other fires are reported to be burning in the northern districts of Viseu and Viana do Castelo. Firefighting aircraft from France, Germany, Italy and the Netherlands are participating in control activities following an appeal for help by Portugal’s government. This international assistance supplements a national firefighting effort of 49 aircraft, around 800 vehicles and 3000 firefighters.

The images here come from the Medium Resolution Imaging Spectrometer (MERIS) aboard Envisat, Europe’s largest-ever Earth Observation satellite, operating in Reduced Resolution mode for a spatial resolution of 1200 metres.

Original press release: Envisat sees smoke from Portuguese wildfires (ESA)