Terry Deshler (in green jacket), a UW professor of atmospheric science, and his team
technician, push the balloon launcher away from the facility and toward the tarmac.
For more than 40 years, University of Wyoming faculty have been launching research balloons where the skies are not cloudy all day, giving UW the distinction of being the nation’s research institution with the longest running program for measuring stratospheric aerosol.
Since 1971, when then-UW physics professors Jim Rosen and Dave Hofmann launched their first research balloon into the heavens, university researchers and graduate students have looked to the sky for answers about Earth’s climate and ozone levels.
“We are the only place in the world that flies mid-size balloons to measure stratospheric aerosol,” says Terry Deshler, a UW professor of atmospheric science. (For a related story about the Nov. 16 launch, go to http:uwyo.edu/news/2012/11/balloon-research-launch-requires-teamwork,-early-start.html).
The National Scientific Balloon Facility (NSBF) in Texas and the Center for National Studies of Space (CNES) in France also use balloons for stratospheric research, but their flights are infrequent. NSBF and CNES fly their own balloons, but rely on other scientists for the measuring instruments. UW, by contrast, typically makes six flights a year, or once every two months, and uses its own measuring equipment, Deshler says.
Even though this particular type of research using balloons began in the late 1950s in South Dakota, UW has been measuring stratospheric aerosol longer than anyone else, Deshler says. Facilities in Brazil, Germany and Hawaii have conducted stratospheric aerosol measurements -- using Lidar -- since 1974 and continue to this day. Another, in Hampton, Va., also began using Lidar for such experiments in 1974, but stopped its program around 2003. Lidar, an acronym for light detection and ranging, is an optic remote sensing technology.
“We make (aerosol particle) measurements with balloons. Other researchers measure this using Lidar and satellites,” Deshler says. “(The University of) Wyoming is unique in that we started this earlier than anyone else and continued it since. We are making particle size and concentration measurements (of aerosol), which no one else makes.”
God’s country is ideal
There are reasons ballooning is not used widely for such research. One, it is expensive and, two, the places where it can be done are limited. Deshler says European countries once used balloons for such research in Europe, but don’t any more as population densities have increased there. It is not feasible to conduct such research on the U.S. East Coast, because the balloons would end up in the ocean, he says.
Wyoming, however, is ideal for such research because it has the lowest population of any state and there are many days with clear skies, which keeps the balloons visible to aircraft. Winds, when coming from the west-northwest or southwest, are correct for the balloons’ trajectory, which keeps them away from airspace over Denver International Airport and away from the mountains.
“It’s kind of serendipity that they (Rosen and Hofmann) came to Wyoming,” says Deshler,
who became involved with the aerosol measurement research at UW as a post-doctoral
researcher in 1988. He took
over as principal investigator in 1991, when Hofmann retired. “We’ve been doing this
for more than 40 years now.”
A continual funding source -- courtesy of the National Science Foundation (NSF) -- has been a key element for this research to endure without interruption.
“NSF has been a funder from day one,” Deshler says appreciatively.
Over the years, NASA and the Naval Research Laboratory also have funded UW’s aerosol measurement research, he says.
Research highlights
Over time, there have been a number of scientific highlights in Laramie. Aerosol particles -- in size and number -- showed spikes in the stratosphere, due primarily to volcanic events. Deshler points to a series of black-and-red colored charts -- depicting normal and volcanic-effected aerosol levels – which are part of a reference book chapter in which he was the lead author.
The chapter, which reviewed stratospheric aerosol trends from 1971-2004, was part of a reference book titled “SPARC Assessment of Stratospheric Aerosol Properties.”
SPARC stands for “Stratospheric Processes and Their Role in Climate” and is a project of the World Meteorological Organization, International Council for Science and the International Ozone Commission.
With enthusiasm, Deshler rattled off stratospheric changes due to the El Chichon eruption in southeastern Mexico in 1982; the change in non-volcanic aerosol in 1988 (dating before the Pinatubo eruption); and the largest eruption of a volcano -- Pinatubo in 1991 -- during the last 50 years.
“What’s exciting about the record is that we see the impacts on the stratosphere from large volcanic eruptions throughout the world, and can look for less dramatic effects on the stratosphere in the absence of volcanoes,” he says.
These eruptions are important for analyzing short-term regional and global effects on climate from enhanced stratospheric aerosol loading, according to information in Deshler’s book chapter.
Aerosol measurements provide four significant types of data, Deshler says.
One, measurements show whether there have been changes in the material in the stratosphere and the source of material that reaches the stratosphere. These can range from aerosol clouds from volcanoes, natural emissions, biological emissions produced by fires or sea plankton, bacterial emissions, and sulfur byproducts created by coal combustion, Deshler says.
Second, stratospheric aerosol can do two things relevant to radiation. The particles scatter sunlight back to space, which has a cooling effect. The aerosol also can absorb infrared radiation from the Earth, which has a local warming effect, he says.
Third, stratospheric aerosol provides a surface for chemical reactions that affects ozone levels, Deshler says.
“The ozone is controlled, to some extent, by particles in the atmosphere, particularly when volcanic activity is at a minimum,” he says.
And fourth, a number of satellites record various measurements that require knowledge of the stratospheric aerosol size distribution. Some satellites, which measure molecular concentrations, have to make assumptions about the atmospheric aerosol to quantify their results, Deshler says.
“Mother Nature keeps dealing us hands that are interesting in their own right,” Deshler says. “We, as scientists, have to look at why aerosol measurements are important.”
