UCAR Communications


staff notes monthly

July/August 2003

Can air pollution reduce mountain snowpacks? The answer appears to be yes, based on a research project involving ATD’s Steve Cohn and Bill Brown, along with scientists at the Desert Research Institute’s Storm Peak Laboratory in Steamboat Springs. The Inhibition of Snowfall by Pollution Aerosols project, funded by an NSF grant, has found evidence that heavy concentrations of aerosols, or airborne particles, prevent falling snow from gathering much rime ice. This occurs because increasing the number of aerosols decreases the size of cloud droplets (which are the source of rime ice) and smaller droplets cannot adhere easily to falling snow. As a result, a storm will leave more moisture in the atmosphere instead of depositing it on the ground—which can significantly reduce snowfall totals in some upslope areas. The researchers, including principal investigators Randolph Borys and David Lowenthal of the Desert Research Institute, set up ATD’s Multiple Antenna Profiler Radar (MAPR) near Steamboat Springs to determine wind speed and direction and to measure changes in the snow intensity with height. For more on this project, see www.atd.ucar.edu/rtf/projects/snowfall.

John Braun and Chris Rocken (GST) are working on a water vapor tomography project as a follow-up to last summer’s IHOP (International H2O Project) field experiment. One of IHOP’s goals was to improve warm season rainfall prediction, an especially difficult forecast for models to make accurately. Using data from existing and supplemental networks of GPS (Global Positioning System) stations, John and Chris are focusing on a few cases of convective storms from May and June of 2002 in the Oklahoma/Kansas region. The GPS data recreate water vapor density fields and comprise three-dimensional information about the distribution of vapor in a given region. The research helps identify areas where a convective storm, such as a thunderstorm, has enough water vapor to potentially form rain or severe weather. Chris and John hope this information will allow researchers to define, study, and model the three-dimensional water vapor field and how it evolves during rainfall events. Eventually, this could help improve both nowcasting and weather prediction. For more on IHOP, see www.atd.ucar.edu/dir_off/ projects/2002/IHOP.html. For a map of the GPS locations, see www.gst.ucar.edu/~braunj/ihop.html.

NCAR scientists, as well as researchers from such institutions as the University of Michigan and NASA, are working on the Sun-Earth Connection project. A team from HAO, including Maura Hagan, Gang Lu, Art Richmond, Ray Roble, Stan Solomon, and Qian Wu, is studying the upper atmospheric effects of April 2002 coronal mass ejections (massive explosions in the outer atmosphere of the sun) and the accompanying solar flares. While the effects of solar activity on Earth have been well established, this multi-institutional project is tracking the complete Sun-Earth system during ejections for the first time. Coronal mass ejections can set off geomagnetic storms in Earth’s atmosphere, disrupting communications and other sensitive electronics systems and affecting ozone and other atmospheric chemicals. Project researchers are hoping to quantify particle and energy transfers and magnetic fluctuations that accompany coronal mass ejections and solar flares.

Thermohaline circulation in the oceans (the movement of water driven by temperature and salinity variations) plays an important role in global climate. But the circulation patterns have varied over time, with the North Atlantic Deep Water circulation stronger now than it was 21,000 years ago during a period known as the Last Glacial Maximum. CGD’s Bette Otto-Bliesner and a team of University of Wisconsin–Madison scientists, including lead author Sang-Ik Shin, used the Community Climate System Model at NCAR to explore why the patterns have changed. They found that, during the Last Glacial Maximum, a combination of strong westerly winds and sea ice drifting from the Southern Ocean equatorward enhanced the Antarctic Bottom Water current, helping it to penetrate farther into the North Atlantic. The research not only sheds light on the reasons for shifting ocean circulation but also provides evidence that NCAR’s model can accurately capture past climate trends.

ESIG’s Mickey Glantz has written a primer, Climate Affairs, that details his vision for multidisciplinary academic programs on climate and society. The wide-ranging book, published this spring by Island Press, draws on atmospheric science, history, international law, and other disciplines to illustrate how climate affects virtually all aspects of our lives. It makes a powerful case for policy makers to take climate into account when they make decisions because this will reduce the scope of climate-related disasters. The concept of a climate affairs course of study has stirred considerable interest overseas. The Asian Institute of Technology in Bangkok is creating a climate affairs program, and universities and governmental organizations in China, Japan, and Malaysia, including the United Nations University in Tokyo, also are developing climate affairs classes. For background on climate affairs, see www.esig.ucar.edu/alerts/alert4.pdf.

Also in this issue...

Taking charge of GLOBE

Ann-Elizabeth's iggies

A SOARS summer

One hail of a storm

Fire Season

Tackling the MS150

Delphi Question: Priarie dog display

NCAR names two new senior scientists


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