What are aerosols? In this case they are tiny particles of dust, soot, salts, mist and all sorts of small stuff suspended in the air. This is what causes a hazy day, light scattering and sun light absorption. Aerosols have a great effect on climate but little is known about them.
Aerosols can be natural such as volcanic in source or manmade.
Some aerosols, particularly sulfate aerosols from fossil fuel combustion, exert a cooling influence (by the reflection or absorption of sunlight before it reaches the earth) on the climate which partly counteracts the warming induced by greenhouse gases such as carbon dioxide. Other effects are far from clear or known.
Recent studies of the Sahel drought and major increases since 1967 in rainfall over the Northern Territory, Kimberley, Pilbara and around the Nullarbor Plain have led some scientists to conclude that the aerosol haze over South and East Asia has been steadily shifting tropical rainfall in both hemispheres southward.
So now more than 60 scientists from a dozen institutions have converged on this California urban area to study how tiny particles called aerosols affect the climate. Sending airplanes and weather balloons outfitted with instruments up in the air, the team will be sampling aerosols in the Sacramento Valley June 2-28.
Researchers from the Department of Energy's Pacific Northwest National Laboratory in will be leading the month long study, coordinating air and ground operations at three sites in the Central Valley. The data they are collecting will help researchers improve computer models that simulate the climate and project climate changes.
To better understand aerosols' role in climate, the DOE's climate research program studies how aerosol particles in the air scatter and absorb the sun's radiation, and how much of it hits Earth.
The team of researchers will take daily measurements of trace gases and aerosols the city emits (known as the Sacramento urban plume) under relatively well defined and regular weather conditions. The knowledge gained will eventually be used in regional and global computer models that simulate the effects of aerosols on climate.
About half of the researchers will take measurements on the ground at two sites. The rest of the team will take similar measurements from the air flown on a Gulfstream-1 aircraft at about 1,000 feet. NASA will fly a King Air B-200 even higher at 28,000 feet.
In addition, the team will be sending weather balloons up for additional sampling from the ground sites. The simultaneous measurements from ground, plane and balloon will provide a comprehensive view of the atmospheric aerosols.
From all this the scientists hope to piece together how the aerosols (and the various sub types of aerosols) affect the climate.
For further information: http://www.pnl.gov/news/release.aspx?id=801