The composition and optical absorption coefficient of atmospheric particulate matter

Variations in the optical properties of terrigenous mineral‐rich particulate matter suspended in seawater

“…The absorption by calcite particles within the examined range of visible and near-IR wavelengths is so low (Lindberg 1975;Sokolik and Toon 1999) that it can be assumed negligible for our purposes. For the calcite samples, CAL 1 and CAL 2 , we calculated the parameter a(l) 5 OD a (l)/OD c (l), where the optical densities OD a and OD c are baseline-corrected.…”

“…We start with an assumption that the optical property of the bulk medium can be related to the optical properties of the medium constituents and their respective volume fractions. On assuming that the mixture of two constituents, pure water and particles immersed in water, behaves as an effective medium that satisfies the Biot-Arago mixing rule with volume additivity, we can write the bulk absorption coefficient of the mixture as (e.g., Lindberg et al 1999)…”

“…In actuality, there appears to be no simple answer to this question because seawater might contain a great diversity of particle types with different optical properties. These types range from particles that have negligible absorption in the near-IR, like much organic matter, to particles that can absorb very efficiently, like black elemental carbon originating from natural combustion processes (forest and grassland fires) and anthropogenic contributions (fossil fuel combustion) (Lindberg et al 1993). In view of such diversity, indiscriminate generalizations with regard to near-IR absorption do not seem to be warranted.…”

“…The bulk of this matter could be considered to be composed of weak absorbers in the visible and near-IR, such as quartz, calcite, silicate clay minerals, and several simple salts. Added to this mixture is the small (but highly variable) amounts of strong absorbers, such as oxides of iron and black carbon (Lindberg 1975;Lindberg et al 1993;Sokolik and Toon 1999).…”

Light Absorption by Carbonaceous Particles: An Investigative Review

“…However, the first systematic measurements of aerosol absorption were made in the early 1970s at the University of Mainz (Fischer 1970) and at the University of Washington (Lin et al 1973). Some of the first measurements of absorption due to mineral dust were made by groups at White Sands, New Mexico (Lindberg 1975) and Leningrad, Soviet Union (Kondratyev et al 1973). …”