Theoretical research efforts at Caltech have been concerned with the development of mathematical models for the physics and chemistry of atmospheric gases and aerosols, models that can be used to determine the emission control needed to achieve desired air quality improvements. Models of air pollution are similar in many respects to those of combustion, involving the coupling of exceedingly complex chemistry and physics with three-dimensional flows. These models are implemented on parallel supercomputers such as the Intel Delta. Also, atmospheric turbulent diffusion processes must be appropriately represented and, finally, when all inputs are assembled, numerical techniques must be developed to solve the resulting coupled partial differential and integrodifferential equations. Caltech researchers have also developed a novel mixing and flow system for nucleation of single and multiple vapors.
Aerosols are ubiquitous in the troposphere and stratosphere.
The net effect of tropospheric aerosols on climate has been estimated, with a large uncertainty, to have a magnitude equal to that of greenhouse gas forcing, but opposite in sign. Clouds are a major determinant of the earth's albedo, and well over half the earth's clouds are over the ocean. At Caltech we have mounted an effort to understand in a fundamental way the process involving aerosols and clouds in the global atmosphere. We have developed a new aerosol sizing instrument that is capable of measuring particles in real time down to 3 nm in diameter, and thus can be used in situ in the atmosphere to detect the formation of new particles by nucleation. The instrument has been flown in field studies over the Pacific to attempt to understand the interaction between aerosols and cloud formation.