AEROSOL PARTICLES, ATMOSPHERIC RADIATION, AND CLIMATE CHANGE

AEROSOL PARTICLES, ATMOSPHERIC RADIATION, AND CLIMATE CHANGE 

Aerosol particles have been thought for many years to play a role in global climate. For example, as discussed in Section E.l, while the mean global surface 

TABLE 14.7 Direct Radiative Forcings per Unit Concentration for Some Fluorinated Compounds0 and Relative Global Warming Potentials Taking GWP(CFC-11) = 1.0b,c or GWP (C02) = 1.0 

In addition, aerosol particles have indirect effects. The most important of these is their effect on cloud properties, since clouds obviously also have major effects on climate. In addition, since heterogeneous chemistry can occur on aerosol particles (see Chapter 5), it is possible that such chemistry can alter the concentrations of other contributors to the climate system, such as the greenhouse gases. One example is the formation of N20 from reactions of HONO on the surface of aerosol particles (see Chapter 7.C). 

As will be evident from the following, this is an area in which there are a number of uncertainties and which at the time of writing is a very active area of research. For reviews, see Penner et al. (1994), Schwartz (1994), Andreae (1995), Charlson and Heintzenberg (1995), IPCC (1996), National Research Council (1996), and Andreae and Crutzen (1997). 

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Atmospheric aerosol particles modify the radiative transfer in the atmosphere and they have an impact on the cloud formation. Therefore, they alter the weather and they have an impact on climate. The anthropogenic part of this modification of the state of the atmosphere is currently not well understood and it raises the largest uncertainties with respect to climate change (see the IPCC report 2007). We developed a new on-line model system to investigate the aerosol-radiation-interaction on the regional scale. 

The climatic effect of the smoke aerosols is beyond current understanding because of the complex nature of the interactions involved. Aerosols can influence climate directly by changing Earth s radiation balance. They reflect sunlight back into space. Smoke particles also contain black (elemental) C, which may strongly absorb sunlight and thus cause a heating of the atmosphere and less penetration of... 

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