GLOBAL THREE-DIMENSIONAL SIMULATION AND RADIATIVE FORCING OF VARIOUS AEROSOL SPECIES

摘要

A global three-dimensional transport model that can simultaneously treat main tropospheric aerosols, i.e., carbonaceous (organic and black carbon), sulfate, soil dust, and sea salt, is developed. It is coupled with an atmospheric general circulation model, and the meteorological field such as wind, temperature, and specific humidity used in the model can be nudged by reanalysis data. Simulated results are compared with not only observations for aerosol concentrations but also the optical thickness and Angstroem exponent retrieved from remote sensing data. A general agreement is found between simulated results and observations spatially and seasonally. The present model can also calculate the single scattering albedo and the radiative forcing for a mixed state of various aerosol species. The single scattering albedo is estimated to be close to 1 over remote ocean, from 0.8 to 0.9 over land, and about 0.8 over desert and bipmass burning regions, which is consistent with optical observations. It is suggested that the direct radiative forcing of aerosol particles absorbing the solar radiation is sensitive to surface albedo, cloud amounts, and altitudes of cloud layers.