The Effects of Meteorology on Marine Aerosol and Optical and IR Propagation,
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
Optical and IR propagation can be strongly influenced by aerosol in the marine boundary layer. The effects are wavelength dependent and there is no best wavelength to use in all cases. There are sources and sinks of this aerosol in operation over the ocean which can be predicted from a full knowledge of the meteorological situation. Once airborne the spatial distribution of the aerosol is a function of the mixing processes, the micrometeorology of the marine boundary layer as well as the history of these processes to which the aerosol is exposed. Much of the marine aerosol is hygroscopic which means that the size of individual particles depends on the ambient relative humidity to which they are exposed. Since the relative humidity in the marine boundary layer is high, the aerosol has the form of small spheres or droplets. The index of refraction of these droplets is also a function of the relative humidity being close to that of water for relative humidities close to 100 percent. The marine aerosol size distribution, which describes the concentration of droplets for each size class, can be modeled from standard meteorological parameters. Once this function is known, the resultant extinction and absorption can be calculated from the size distribution for wavelengths of from 0.2 to 40.0 micrometers using Mie theory.