American Geophysical Union, Fall Meeting 2008
Anecdotal evidence suggests that Rocky Mountain snow is at its fluffy best when winds have blown salt and other particles eastward from Utah's Great Salt Lake. Now analysis of individual aerosol particles, a new area of research pioneered at Scripps Institution of Oceanography at UC San Diego, might lend credence to skiers' perceptions. Chemistry Professor Kim Prather and colleagues have collected new evidence showing that different types of dust activate cloud formation and influence precipitation in different ways around the planet.
Prather will discuss details of recent atmospheric measurements during her talk at the 2008 American Geophysical Union Fall Meeting (Thursday, Dec. 18, 10:20 a.m. · Moscone West 2011).
"This study makes direct in-situ measurement of the particles making up
the clouds over the midwestern United States," said Prather. "It shows the importance of suspended dust in the region to cloud formation which has implications for precipitation patterns in this area.
Very little attention has been paid to this region of the United States as a potential source of suspended dust, which may affect climate patterns compared to other dust source regions of the world."
Given that climate change is increasing the frequency of dust storms and changing land use patterns in arid regions, dust is wielding greater influence on atmospheric processes. Additionally, scientists are beginning to fully appreciate aerosols as a key player in biological activities through their airborne transport of nutrients in marine and terrestrial ecosystems.
Prather's research is revealing the complexity of dust and how much it varies regionally. The regional character of dust and other aerosols leads to differences in how effectively they form clouds. Differences in the chemistry of dust, ignored in most current climate models, can strongly impact their ability to form liquid and ice nuclei. These differences impact the so-called indirect effect of aerosols, which represents the single largest remaining uncertainty in climate change research. Understanding these processes and the impacts of dust particle mineralogy will allow development of models that can provide a more accurate picture of future climate change.
Prather's team has employed an innovative method of mass spectrometry to analyze aerosol and cloud nuclei one-by-one on an aircraft. The researchers have sampled a wide range of dust and other particles from ground-based instruments and aircraft in areas ranging from Southeast Asia to greater Mexico City to the midwestern United States. Prather will present results of data collected by the aerosol time-of-flight mass spectrometer (ATOFMS) that she and her research group have developed.
Among her findings is that salts from the Great Salt Lake appear to strongly affect cloud formation over neighboring Colorado and other Great Plains states.
"This level of detail has never been shown before," said Prather. "Being able to rapidly measure the size and chemistry of individual cloud nuclei within clouds and compare this to simultaneous cloud property measurements is offering us new insights into the key processes contributing to cloud formation."
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