Tropical Cloud Study Concludes; Science Students Play Key Role
Media Contact: Lynne Roeder, 509.372.4331
Three and a half weeks after it started, the Tropical Warm Pool International Cloud Experiment has resulted in one of the most comprehensive data sets of tropical cloud properties ever collected. Co-led by scientist from the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Program and the Australian Bureau of Meteorology (BoM), these data will be used by scientists for years to come, as they seek to refine computer models for forecasting regional weather and simulating climate change.
"We have collected an extraordinary dataset with measurements of tropical cirrus cloud properties and the environment in which they are formed" said Dr. Jim Mather, the ARM Program's lead scientist for the endeavor. "Cirrus clouds associated with the outflow of convective storms are very prevalent in the tropics. These high altitude clouds impact the energy exchange between earth and space, and have a large impact on climate and global weather patterns. The data set obtained here in Darwin will significantly advance our understanding of this important component of the climate system."
This unprecedented tropical data set was obtained via highly sophisticated instruments including radars and in-cloud ice particle sensors located on a fleet of aircraft, a research ship, and a network of ground sites in a 200-km ring around Darwin, Australia. Its location near the equator and the significant meteorological infrastructure and forecasting support from BoM, combined with ARM's permanent climate research facility established in 2002, made Darwin the ideal spot for conducting such an experiment.
Twenty missions with multiple aircraft flying at altitudes ranging from 60 feet to 55,000 feet were completed throughout the course of the experiment, providing critical in situ cloud observations. In addition to showing researchers the composition of these high altitude clouds, the in-cloud observations will be used to refine cloud properties derived from long-term data obtained at the ARM site in Darwin.
Planning for the campaign was a three-year process involving scientific organizations from around the world, resulting in as a highly complex, very involved field campaign.
"Once our plans started coming together, several other organizations such as NASA decided they wanted to participate too," said Dr. Peter May, BOM's lead scientist for the experiment. "This added significantly to both the aircraft and ground based components. For example, the University of Manchester (United Kingdom) brought additional aircraft that were highly complementary to our plans. The combined efforts have produced an incredibly complete and diverse set of data."
"Another major contributor was Australia's floating laboratory, the Southern Surveyor, provided by the Commonwealth Scientific and Industrial Research Organisation," May added. "The crew endured gale force winds to provide us with a fantastic data set for understanding tropical climate."
The science team also had the assistance of graduate students from many institutions. They gained valuable field experience by helping to conduct the experiment, including performing routine but important daily activities.
One of these key daily activities involved launching weather balloons every three hours at the network of ground sites around Darwin, including the ship. Students were responsible for inflating the weather balloons, attaching to them a small sensor package (called a radiosonde), and then launching them at the same times every day. Measurements of wind speed, wind direction, pressure, temperature, and humidity obtained by each radiosonde were picked up by an antenna at the associated ground station. These measurements provided a detailed record of meteorological conditions within the experiment domain throughout the course of the experiment.
"It's certainly not the most glamorous job. Being posted in remote locations—including a ship at sea—for weeks on end, launching weather balloons at three-hourly intervals, is hard work. However, without the sonde data the experiment's major objectives could not have been achieved" said Dr. Christian Jakob, senior research scientist with the BoM who supervised activities at the radiosonde sites. "The students were great; they really approached the task with enthusiasm, and took initiative to conduct troubleshooting when things didn't go quite as planned. Let's face it; it's better than a classroom. Quite a few of the students involved in this experiment will likely encounter the data they gathered in their own future research activities, and all of them will remember what they experienced here."
In addition to staffing the sonde sites, the students also helped monitor, collect, and analyze the data, as well as assisting with various logistics needs at experiment headquarters at Charles Darwin University. More than 30 university students, including about 10 from the United States, participated in the international field campaign, which officially began on January 21 and ended on February 13.
More information is available at the TWP-ICE website: http://science.arm.gov/twpice/
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The ARM Program—the Department of Energy's largest global change research program—was created to help resolve scientific uncertainties related to global climate change. Its specific focus is on the crucial role of clouds and their influence on radiative feedback processes in the atmosphere.
For more information about the ARM Program, visit www.arm.gov.