Researchers Team with Airline to Pinpoint Turbulence in Clouds;

A new turbulence detection system now being tested is alerting pilots to patches of rough air as they fly through clouds. The system, designed by the National Center for Atmospheric Research (NCAR) and tested by United Airlines on commercial flights, is designed to better protect passengers from injuries caused by turbulence while reducing flight delays and lowering aviation costs.

The new system uses a mathematical method developed by NCAR scientists, known as the NEXRAD Turbulence Detection Algorithm, or NTDA, to analyze data obtained from the National Weather Service's network of Next-Generation (NEXRAD) Doppler radars. The resulting real-time snapshot of turbulence can be transmitted to pilots in the cockpit and made available to airline meteorologists and dispatchers via a Web-based display.

The research is funded by the Federal Aviation Administration (FAA) in partnership with the National Science Foundation, NCAR's primary sponsor.

"Pinpointing turbulence in clouds and thunderstorms is a major scientific challenge," says NCAR scientist John Williams. "Our goal is to use these radar measurements to create a three-dimensional mosaic showing turbulence across the country that can help pilots avoid hazardous areas, or at least give them enough warning to turn on the 'fasten seat belt' sign."

The NTDA is being tested until October by a group of United Airlines pilots who fly routes east of the Rockies. The pilots, who receive information in their cockpits about turbulence detected ahead, report that the system provides them with accurate information about turbulence that is not available from any other source.

"The messages I've received in the cockpit gave a very accurate picture of turbulence location and intensity," says Captain Rocky Stone, chief technical pilot for United Airlines. "The depiction of turbulence intensity provides an unprecedented and extremely valuable new tool for pilot situational awareness."

Depending on the results of this year's tests, the next step may be to expand the system to additional United aircraft or other airlines. Williams anticipates that, by 2011, the NTDA will provide input to a system over the contiguous United States that will update comprehensive turbulence "nowcasts" for pilots and air traffic managers every 15 minutes.

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Volcanic Activity Key to Oxygen-rich Atmosphere

Next time you catch a breath, be thankful, for a change, that the Earth's surface is dotted with volcanoes.

National Science Foundation-funded research published in the journal Nature indicates that billions of years ago, when the Earth was home largely to undersea volcanoes, some previously unknown agent was removing the gas.

The researchers suggest that mixture of gases and lavas produced by submarine volcanoes scrubbed oxygen from the atmosphere and bound it into oxygen-containing minerals.

Lee Kump, a professor of geosciences at Penn State University, working with a colleague at the University of Western Australia, looked at the geologic record from the Archaean--a geologic period from 3.8 to 2.5 billion years before the present day--and the Palaeoproterozoic-- geologic era immediately following that featured profound global change that included the breakup and formation of two supercontinents. They found that in the Archean there was a dearth of terrestrial volcanoes, while in the Palaeoproterozoic, although submarine volcanoes continued to be common, the population of terrestrial volcanoes increased dramatically.

"The rise of oxygen allowed for the evolution of complex oxygen-breathing life forms," Kump says.

Terrestrial volcanoes could become much more common because land masses stabilized and the current system of tectonics regime took shape.

Because submarine volcanoes erupt at lower temperatures than terrestrial volcanoes, they are more efficient at converting--or "reducing"--oxygen. As long as the reducing ability of the submarine volcanoes was larger than the amounts of oxygen created, the atmosphere had no oxygen. When terrestrial volcanoes began to dominate, oxygen levels increased.

The change over time caused an atmospheric shift from oxygen-free to oxygen-rich, the researchers argue, with profound implications for life on the planet.

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Scientists See First Signs of Long-Term Changes in Tropical Rainfall

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

The international scientific community assembled a 27-year global record of rainfall from satellite and ground-based instruments. The researchers found the rainiest years between 1979 and 2005 occurred primarily after 2001. The wettest year was 2005, followed by 2004, 2003,
2002 and 1998. The study appeared in the August 1 issue of the American Meteorological Society's Journal of Climate. The rainfall increase was concentrated over tropical oceans, with a slight decline over land.

"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 NASA's
Goddard Space Flight Center in Greenbelt, Md.

Climate scientists 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 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 investigate the possible link further.

Obtaining a global view of our planet's rainfall patterns is a challenge. Only since the satellite era have regular estimates of rainfall over oceans been available to supplement the long-term, but land-limited record from rain gauges. Recently, the many different land- and space-based
data have been merged into a global record: the Global Precipitation Climatology Project, organized under the World Climate Research Program.

Using this global record, the scientists identified a small upward trend in overall tropical rainfall since 1979. To assess whether this pattern was a long-term trend rather than natural year-to-year variability, they removed the effects of the two natural phenomena that change rainfall:
the El Nino-Southern Oscillation and large volcanic eruptions.

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