Aerosol microphysics

Wagner, P. E., in Topics in Current Physics Vol. 29 Aerosol Microphysics II Chemical Physics of Microparticles. W. H. Marlow, ed., Springer-Verlag, Berlin, 1982. 

We have investigated the atmospheric implications ot our newly calculated absorption cross sections with the Garcia-Solomon 2D dynamical/chemical model [85,86], to which we have added sultur chemistry and aerosol microphysics [87]. The model spans 56 pressure levels trom 2 to 112 km above sea level, and 36 latitudes trom 89.5°S to 89.5°N. Further details ot the sultur chemistry and... 

For the realisation of all aerosol forcing mechanisms in integrated systems it is necessary to improve not only ACTMs, but also NWP HIRLAM. The boundary layer structure and processes, including radiation transfer (Savijarvi 1990), cloud development and precipitation must be improved. Convection and condensation schemes need to be adjusted to take the aerosol-microphysical interactions into account, and the radiation scheme needs to be modified to include the aerosol effects. Incorporation of the aerosol direct effects (radiation forcing) is very problematic within the Savijarvi (1990) radiation scheme. 

The modal approach assumes a shape for the particle-size distribution, typically one or more lognormal distributions, and represents evolution of the size distribution as evolution of the parameters characterizing the distribution, i.e., the amplitude, mode radius, and variance for the lognormal distribution (Binkowski and Shankar, 1995 Wilck and Stratmann, 1997). This approach offers the possibility of representing aerosol microphysical properties in models with far fewer variables (modal parameters) than are required in the sectional method (numbers of particles in each bin). 

Wright D. L., Kasibhatla P. S., McGraw R., and Schwartz S. E. (2001) Description and evaluation of a six-moment aerosol microphysical module for use in atmospheric chemical transport models. J. Geophys. Res. 106, 20275-20291. 

Marlow WH. Survey of aerosol interactive forces. In Aerosol Microphysics I Particle Interaction Marlow WH, ed. McGraw-Hill New York, 1980 116-156. 

Gras, J. L. (1991) Southern hemisphere tropospheric aerosol microphysics, J. Geophys. Res. 96, 5345-5356. 

This introductory chapter addresses the concept of the aerosol condition of matter first by explaining how it arose and then by delineating the physical questions which are common to all such systems. Section 1.1 reviews possible definitions of "aerosol" and Sect.1.2 discusses the division among the component studies of aerosol physics which is followed in these volumes. The discussion of aerosol microphysics in Sect.1.2.2 establishes its relationship to the conventional investigations of basic physics. To be of value both to the basic scientist seeking the context of his work in other natural sciences and in technology and conversely to the engineer or natural scientist curious of how his domain of interest is related to aerosol microphysics, Sect.1,3 briefly discusses examples of where aerosols arise. 

The division of physical studies herein termed "aerosol microphysics" is of course somewhat arbitrary. The objective of such a division is to delineate common topics of research investigation and application. In some cases such as photophoresis [1.15], several of these divisions apply in a clearly microphysical problem. Nevertheless, they do identify what are probably the requisite domains of physics... 

Inhaled particulate matter is susceptible to capture by the body in the respiratory system. Depending upon the particle s size, this may occur anywhere from the nose or mouth for the largest particles down to the lung s alveoli for the smallest (under 200 nm). Since the respiratory system presents an environment to the aerosol that is quite different from that outside the body, particle growth and transformation frequently occur, complicating the analysis of deposition mechanisms [1.31,32]. Aerosol microphysical domains of relevance include the thermodynamics of particle growth, kinetic theory, interaction forces,and some aspects of homogeneous nu-cleation theory. 

Cloud formation and dynamics is a subject which requires considerable information from almost all the areas of aerosol microphysics [1.37,18]. Thermodynamics determines aerosol growth to cloud droplet size, and electrical processes in clouds may play a role in the onset of precipitation. Clouds may scavenge the atmosphere of aerosols through capture of particles by cloud droplets, with the rates and mechanisms described by subtleties of their interaction forces and aspects of kinetic theory. 

As is clear from the material discussed in Sect.1.2, the divisions of aerosol microphysics are not of unique relevance only to aerosols but are rather a refinement of more general fields of research. It is, therefore, of interest to note that exactly these same categories of research are necessary in other, nonaerosol related work. A few of the innumerable areas are mentioned. 

In materials science, both the preparation of composite materials and the conditions of use, e.g., catalysts, require access to methods of value for aerosol microphysics. In the former case, aerosol interaction forces play a role not only in understanding the agglomeration properties of the components of the composite, but also in describing the potential for spreading of the interstitial material... 

Energy transfer between a gas and some other system is a process of interest to workers in a number of areas. Depending on whether the second system is another gas molecule, a small aggregate of molecules, or a solid surface gas-phase kinetics, aerosol microphysics, or solid-state studies are involved. Energy-transfer theories are best developed for the gas-phase case where currently available methods provide reasonably reliable treatment for both the interactions and the collision dynamics. 

The domain of importance of the van der Waals interaction for aerosol microphysics is typically for particle separations under a radius. For example, consider two identical spherical particles at room temperature with kT 4.14 X ergs. Assume the particles electric susceptibilities e(x) = 2 for 400... 

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