New research shows that air pollution in eastern China has reduced the amount of light rainfall over the past 50 years and decreased by 23 percent the number of days of light rain in the eastern half of the country. The results suggest that bad air quality might be affecting the country's ability to raise crops as well as contributing to health and environmental problems.
The study links for the first time high levels of pollutants in the air with conditions that prevent the light kind of rainfall critical for agriculture. Led by atmospheric scientist Yun Qian at the Department of Energy's Pacific Northwest National Laboratory, the study appears August 15 in the Journal of Geophysical Research-Atmospheres.
"People have long wondered if there was a connection, but this is the first time we've observed it from long-term data," said Qian. "Besides the health effects, acid rain and other problems that pollution creates, this work suggests that reducing air pollution might help ease the drought in north China."
China's dramatic economic growth and pollution problems provide researchers an opportunity to study the connection between air quality and climate. Rain in eastern China — where most of the country's people and pollution exist — is not like it used to be.
Over the last 50 years, the southern part of eastern China has seen increased amounts of total rainfall per year. The northern half has seen less rain and more droughts. But light rainfall that sustains crops has decreased everywhere. A group of climate researchers from the U.S., China and Sweden wanted to know why light rain patterns haven't followed the same precipitation patterns as total rainfall.
Previous work has shown that pollution can interfere with light rain above oceans, so the team suspected pollution might have something to do with the changes over land. Light rain ranges from drizzles to 10 millimeters of accumulation per day and sustains agriculture. (Compared to heavy rain that causes floods, loss of light rain has serious consequences for crops.)
While the light rains have diminished, pollution has increased dramatically in China in the last half of the 20th century. For example, while China's population rose two and a half times in size, the emissions of sulfur from fossil fuel burning outpaced that considerably — rising nine times.
Air pollution contains tiny, unseen particles of gas, water and bits of matter called aerosols. Aerosols — both natural and human-caused (anthropogenic) — do contribute to rainfall patterns, but the researchers needed to determine if pollution was to blame for China's loss of rain and how.
To find out, the team charted trends in rainfall from 1956 to 2005 in eastern China, which has 162 weather stations with complete data collected over the entire 50 years.
From this data, the team determined that both the north and south regions of eastern China had fewer days of light rain — those getting 10 millimeters per day or less — at the end of the 50 year timespan. The south lost more days — 8.1 days per decade — than the north did, at 6.9 days per decade. However, the drought-rattled north lost a greater percentage of its rainy days, about 25 percent compared to the south's 21 percent.
"No matter how we define light rain, we can see a very significant decrease of light rain over almost every station," said Qian.
Up Up & In the Way
To probe what caused the loss of rainfall, the team looked at how much water the atmosphere contained and where the water vapor traveled. Most parts of eastern China saw no significant change in the amount of water held by the atmosphere, even though light rains decreased. In addition, where the atmosphere transported water vapor didn't coincide with light rain frequency.
These results suggested that changes in large-scale movement of water could not account for the loss of the precipitation. Some of pollution's aerosols can seed clouds or form raindrops, depending on their size, composition and the conditions in which they find themselves. Because these skills likely contribute to rainfall patterns, the researchers explored the aerosols in more depth.
Cloud droplets form around aerosols, so the team determined the concentration of cloud droplets over China. They found higher concentrations of droplets when more aerosols were present. But more droplets mean that each cloud droplet is smaller, in the same way that filling 10 ice cream cones from a quart of ice cream results in smaller scoops than if the same amount were put in only five cones.
This result suggested that aerosols create smaller water droplets, which in turn have a harder time forming rainclouds. The team verified this with supercomputer models of pristine, moderately polluted or heavily polluted skies. In the most heavily polluted simulation, rain fell at significantly lower frequencies than in the pristine conditions.
An examination of the cloud and rain drops showed that these water drops in polluted cases are up to 50 percent smaller than in clean skies. The smaller size impedes the formation of rain clouds and the falling of rain.
Qian said the next step in their research is to examine new data from the DOE's Atmospheric Radiation Measurement Climate Research Facility in the central eastern Chinese city of Shouxian. The data was collected from April to December of 2008.
"This work is important because modeling studies of individual cases of pollution's effect on convective clouds have shown varying results, depending on the environmental conditions," said coauthor Ruby Leung. "The ARM data collected at Shouxian should provide more detailed measurements of both aerosols and clouds to enable us to quantify the impacts of aerosols on precipitation under different atmospheric and pollution conditions."
The work was supported by the Office of Biological and Environmental Research within the DOE Office of Science under a bilateral agreement on regional climate research with the China Ministry of Science and Technology.
Internationally Renowned Institute to Employ Newly Announced SGI Supercomputer to Accelerate Cancer Research
SGI today announced that the Institute of Cancer Research (ICR) has selected SGI Altix UV, based on Intel Xeon processors (codenamed Nehalem-EX), to support its future life-saving research. The ICR joins the growing list of globally significant high performance computing (HPC) facilities embracing Altix UV as the future of open, high performance, big-memory supercomputing. Altix UV will provide the ICR with a massively scalable shared memory system to process its growing data requirements, including hundreds of terabytes of data for biological networks, MRI imaging, mass-spectrometry, phenotyping, genetics and deep-sequencing information across thousands of CPUs.
“The Altix UV supercomputer will allow extremely large, diverse data sets to be processed quickly, enabling our researchers to correlate medical and biological data on an unprecedented scale,” said Dr. Rune Linding, cellular and molecular logic team leader at the ICR. “Eventually, this will lead to network-based cancer models that will be used to streamline the process of drug development.”
SGI Altix UV supports up to 16 terabytes of global shared memory in a single system image. It remains highly efficient at scale for applications ranging from in-memory databases to a diverse set of data and compute-intensive HPC applications. As a result, Altix UV is the only hardware solution equipped to meet the vast data processing requirements of the ICR.
“Altix UV will allow HPC customers like the ICR to think differently and solve problems that cannot be solved on other HPC platforms,” said Rod Evans, vice president of sales for Northern Europe at SGI. “We are delighted to be working with the ICR to provide this unique technology required to process the huge amounts of cancer-related data generated in medical research.”
“Systems biology demands massive integration of extremely large data sets. Large shared memory should enable us to handle such data at a much higher speed and with a greater focus on the biological questions at hand,” said Peter Rigby, chief executive professor at ICR. “Altix UV should significantly help our work in this new, exciting area of cancer research.”
"With its upcoming SGI Altix UV deployment, the ICR will be at the forefront of HPC for biological research as it pursues treatments for cancer,” said Richard Dracott, general manager of high performance computing at Intel. "Altix UV will meaningfully transform HPC by drawing on large memory capacity, high core count and scalability of our forthcoming next generation Intel Xeon processor-based server platform, for the expandable server segments (codenamed Nehalem-EX)."
A ‘grid’ is a network of high-powered computing and storage resources available to researchers wishing to carry out advanced number-crunching activities. Resources belong to individual universities, national and international laboratories and other research centres but are shared between them by mutual agreement.
In Europe the data is carried over the GÉANT grid network but the organisation that makes this possible is managed by EGEE-III, the third phase of an EU-funded project to create an infrastructure supporting European researchers using grid computing resources.
“We support the users, we operate the infrastructure and we also develop the middleware that we use to bring all those resources together in a secure manner,” says Steven Newhouse, the project’s technical director. “We take computing and storage resources owned by individual institutions and provide a middleware layer of software that allows these resources to be shared securely over the international research networks.”
Coordinated at CERN near Geneva, EGEE links about 14,000 users at 350 sites in 55 countries, both within and outside Europe. Every day, an average of 350,000 computing jobs pass through the network.
Although grid computing began in the high-energy physics community – and EGEE will be on hand to process the long-awaited data from the Large Hadron Collider – many other disciplines are now using EGEE to access the world’s most powerful computing facilities.
“We're seeing increasing use from the computational chemistry area, from materials science, the life sciences, environmental sciences and so forth,” says Newhouse.
What many of the applications have in common is the simulation of experiments that would take years or decades to do in the laboratory. A common theme is to study how complex molecules interact with each other, with many applications in the search for new vaccines and other drugs.
“And this gives scientists a great way of asking 'what if?' questions and to narrow down the chemicals that they need to explore in the lab from hundreds of thousands to just a handful.”
Research published in Nature Genetics last March used EGEE to identify combinations of genes that predispose people to coronary artery disease. Scientists from the EU’s Cardiogenics project were able to find four out of more than 8.1 million possible combinations of genetic markers that were strongly associated with the disease.
A group in Taiwan is using EGEE to model the effects of earthquakes on urban areas in the hope of learning how to keep damage to a minimum. “It's combining physical sciences and social sciences to do something really practical,” says Catherine Gater, the dissemination manager for EGEE-III.
Another project, AquaMaps, is using the grid to model the worldwide distribution of fish species. “Because climate change is affecting the patterns of where you might find marine species, fish stock management is quite an issue,” she says. “With everything changing so rapidly, the AquaMaps project is mapping where you can find particular species of fish at any one time.”
EGEE is also helping doctors to treat rare diseases through a project to create a worldwide image library. “It gives them almost instant access to medical images spread around the world but in a secure manner,” explains Gater. “That's the key to the grid, that you can share this data with other trusted sources and any patient information is not going to get out beyond the circle that it should.”
The benefits of EGEE have spread beyond the hard sciences and medicine into the humanities. The multidisciplinary ASTRA team in Italy used the grid to construct a digital model of an epigonion, a harp-like instrument used in ancient Greece. The virtual instrument was played in a concert in Naples last December.
From patterns of crime to fine-tuning of radiotherapy treatments, EGEE has brought grid computing to researchers and other professionals who would not have considered using it only a few years ago.
“One of the original motivations for this grid activity was that all this computing power could change the way that scientists do their research,” notes Newhouse. “What we're now seeing, a decade on, are the fruits of all this work.”
Next May, EGEE will come to an end and a new body, the European Grid Initiative (EGI), will take its place. Newhouse is its interim project director. “We want to move away from the short-term project model that has happened within EGEE to a model which is both more sustainable financially but also more sustainable and longer term for the users that increasingly depend upon this infrastructure."
Newhouse likens the grid to other scientific instruments that have changed the way we look at the world. “It’s like the invention of the microscope or the telescope. The grid is actually changing the way scientists think about doing their research and the questions they can pose.”
EGEE-III is an e-Infrastructures project funded under the ‘Research Infrastructures’ part of the Capacities programme of the EU’s Seventh Framework Programme for research.Source: ICT Results site (http://cordis.europa.eu/ictresults)