11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Wednesday, 5 June 2002: 9:15 AM
Scattering and absorption of solar radiation by atmospheric aerosols and clouds
P. Pilewskie, NASA/Ames Research Center, Moffett Field, CA; and R. Bergstrom and M. Rabbette
Efforts to reduce the uncertainty in climate forcing due to the radiative effects of aerosols and clouds have led to the improvement of radiometric sensors used to measure the spectral distribution of solar radiation in the atmosphere. Because much of our current understanding of the solar radiation budget is derived from broadband (spectrally integrated) observations, newer spectrally resolved observations need to be examined in the context of these prior studies. During the past two years a number of intensive field studies have incorporated measurements of moderate resolution solar irradiance spectra and this talk will focus on new information provided by these data . For example, from ARESEII, analysis of solar reflectance and transmittance spectra show that measured cloud absorption follows the expected absorption characteristics of condensed water and water vapor. The impact of these findings on the so-called cloud absorption anomaly will be addressed. In other studies dedicated to dust aerosol radiative forcing, absorption spectra from dust layers have been derived from measurements of vertical profiles of net spectral flux. The measured spectra are consistent with known spectral characteristics of mineral absorption and represent an important new link between aerosol chemical, physical, and radiative properties.

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