(麻豆淫院Org.com) -- During May and June 2009, scientists from the U.S. Department of Energy鈥檚 Brookhaven National Laboratory, Argonne National Laboratory, and the University of Colorado at Boulder will use high-tech scanners 鈥� analogous to those used in medical settings 鈥� to make observations of clouds. The research, conducted at DOE鈥檚 Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) in Ponca City, Oklahoma, could lead to more accurate weather forecasts and predictions about climate.

鈥� play a critical role in Earth鈥檚 weather and climate,鈥� said Brookhaven atmospheric scientist Dong Huang, lead researcher for this study. 鈥淏ut poor understanding of clouds has long limited scientists鈥� ability to make accurate predictions about weather and climate change.鈥�

One major challenge is the sheer scale of the problem: Cloud processes occur on spatial scales ranging from sub-micrometers (millionths of a meter) to thousands of kilometers. The typical probes used by scientists sample a tiny volume. 鈥淯sing these methods, it would take hundreds of years to take readings from an entire cloud, while the typical lifetime of a cloud is just tens of minutes,鈥� said ARM chief scientist Warren Wiscombe, a co-investigator on this study.

To scan a larger area in a short time, the team will use a novel 鈥渃loud tomography鈥� approach to reconstruct three-dimensional cloud structure. 鈥淥ur approach is very similar to x-ray computed tomography (CT), used by doctors to diagnose disease, but this time the patients are clouds,鈥� said Huang. A obtains x-ray data of the body 鈥渟lice by slice鈥� using detectors that rotate around the patient. Similarly a cloud tomography system uses multiple microwave sensors to scan clouds from several distinct ground locations. The interior structure of a cloud can then be inferred from the resultant radiometric measurements using sophisticated algorithms.

The scientists will use a network of five microwave sensors to probe clouds鈥� thermal emission, or release of heat energy, along with two cloud radars, a variety of optical and infrared sensors, and weather balloons to measure other characteristics.

鈥淯sing this combination of instrumentation, we will be able to obtain three-dimensional 鈥榤aps鈥� of the distribution of clouds, atmospheric moisture, and other characteristics over a domain of about 10 kilometers,鈥� said Huang.

The quality of the cloud and moisture reconstructions will be evaluated using concurrent cloud measurements collected by a research aircraft operated by another field experiment led by Brookhaven atmospheric scientist Andy Vogelmann. This study will collect long-term statistics on low-optical-depth clouds.

The combined data will enable scientists to better understand the role of clouds in regulating Earth鈥檚 鈥渞adiation energy鈥� budget 鈥� or how the planet absorbs and re-radiates energy from the sun. These data will also be used to assess the validity of how various cloud processes are represented in computer models of cloud behavior.

鈥淭he combination of intensive field experiments, long-term observations, and modeling will provide important insights that could directly benefit weather forecasting and climate modeling,鈥� Huang said.

Provided by Brookhaven National Laboratory ( : )