Vertical profiles of aerosol optical properties measured during INTEX

Aerosol optical properties are characterized using the number size distributions and scattering coefficients measured from the DC-8 aircraft during Intercontinental Chemical Transport Experiment (INTEX). Numerous vertical profiles over North America provided opportunities to examine the role of diverse aerosol constituents present in the size distribution between 0.1 and 13 um. These were measured with optical and aerodynamic particle counters under dry aircraft conditions and are compared with dry nephelometer light scattering coefficients to check internal consistency, and then adjusted to the ambient conditions with the aid of aerosol volatility, composition and humidity growth data. We will evaluate the varying layers of urban pollution and forest fire particles from different altitudes in the troposphere and their contribution to the column optical properties. These depend on the source, transport mechanism, state of mixture and humidity. This assessment is undertaken with the goal of refining the retrieval parameterizations of satellites such as MODIS, MISR and GOES, and to estimate the effect of water uptake upon regional radiative forcing.